My Ecodial L Technical Documentation V3.4

My Ecodial L Technical Documentation 3.4

Transformers

Input parameters Protection of MV/LV transformers

The role of the transformer is to create a link between the HV network and the LV part of the installation, for installations on which the power requires use of a transformer.

Limitations The power of the transformers proposed by My Ecodial L varies from 50 kVA to 3200 kVA.

The phase to phase voltage at the transformer secondary varies from 220 V to 690 V.

Some transformer connection configurations on the circuit are not authorised. In short, the transformers can be used as a main or replacement sources. In each case, up to 4 transformers can be parallel-connected. For more details, see circuits authorised and circuits refused.

Choice of technology At present, there is a choice of two technologies:

Mineral-oil immersed transformer

Dry type cast resin transformer

To make this choice, a number of parameters must be considered:

Safety of persons, at the transformer and in its vicinity. This safety aspect is dealt with in official recommendations and regulations (standards NF C 27-300 and NF C 17-300). Oil-immersed transformers are forbidden in some applications (tall buildings) and imply installation restrictions due to the fire hazard they represent.

The economic evaluation, in light of the advantages of each technique and the range of existing devices

Determining optimum power Oversizing a transformer leads to:

Excessive investments and pointless no-load losses

Reduction in on-load losses

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Undersizing a transformer leads to:

Full load operation (efficiency which is maximum between 50 and 70% of maximum load is no longer optimum in this case)

Overloads, which can have serious consequences on the installation (temperature rise of windings causing the protection devices to trip) and on the transformer (premature ageing of insulation possibly leading to transformer malfunctions).

Definition of optimum power

To define the optimum power of a transformer, it is important to:

Sum up the installed power.

Determine the percent load of each load

Determine the cycle and load or overload duration of the installation

Compensate for reactive energy consumption if necessary to eliminate penalties and reduce subscribed power (PkVA=PkW/cosj phi)

Choose from the available ratings, allowing for future extensions and dependability considerations.

To size a transformer, My Ecodial L first carries out a power sum for the installation, then chooses, from the standard ratings proposed, the next highest value.

Caution: If installation total power is subsequently reduced, My Ecodial L will not lower the transformer rating as it considers that this may be a deliberate choice on the part of the user to oversize his installation.

Transformer input parameters

My Ecodial L will calculate all the source characteristics from the transformer nominal power and the short-circuit power of the HV network.

First level input parameters

Description Content

Power Rated power (SrT) of the transformer in kVA

Type Two types available: immersed or dry

Earthing arrangement Earthing arrangement of the LV installation: TT - IT - TN-C - TN-S - Upstream (= as defined in the general characteristics)



(1) For TN-C systems, the protective conductor (PE) and the neutral are combined, thus the neutral is considered to be distributed.

(2) Calculation guide UTE C15-500 (CENELEC R064-003) includes two nominal voltage coefficients:

Cmax: voltage factor equal to 1.05 for HV voltage fluctuations. For more details

m: no-load factor, equal to 1.05 to allow for transformer no-load voltage for calculation of maximum short-circuit currents.

(3) These two values make it possible to take into account the maximum number of transformers connected to the same HV network. By default (500 MVA for both values), the transformers are considered to be connected to different networks.

(4) TT systems have separate neutral and ECP earthing electrodes. If this is not the case (RA + RB very low, for example

Distributed neutral Neutral distribution for the LV installation (1): YES-NO

Un Ph-Ph(V) Nominal phase to phase voltage of the LV installation (2): 220-230-240-380-400-415-440-500-525-660-690 V

Short-circuit voltage (%) Transformer short-circuit voltage. Value entered automatically but can be modified in manual mode.

Copper losses (W) Transformer copper losses. Value entered automatically but can be modified in manual mode.

HV Psc max (MVA) and

HV Psc min (MVA) Maximum and minimum values of the short-circuit power of the HV network (3). Default values (for both min and max): 500 MVA

Connection Transformer connection type: Star-Delta Star-Star Star-ZigZag

Network frequency (Hz) Network frequency: 50 - 60 Hz

HV op. time (ms) Operating time of the high voltage protection device: 500 ms by default, 200ms or use of a fuse.

Neutral earthing electrode resistance RA (ohms) Displayed only for TT systems (4)

ECP earthing electrode resistance RB (ohms) Displayed only for TT systems (4)

IMD designation

Designation of the continuous insulation monitor. Characteristics accessible only for IT system. insulation monitoring devices (IMDs) in the data base are accessible via a dropdown list with contents depending on the field of application and network voltage

IMD application field Field of application for IMD choice on an IT system Normal - Hospital

RQ/XQ Ratio used for calculation of transformer resistance (see CENELEC R064-003, § 6.2). Default value: 0,1. Modification of the default value will activate manual mode.

XQ/ZQ Ratio used for calculation of transformer reactance (see CENELEC R064-003, § 6.2). Default value: 0.995. Modification of the default value will activate manual mode.



< 0.5 ohm), use of a TN system is recommended. If the TT system is conserved in spite of this recommendation, the requirements concerning separate neutral and ECP earthing electrodes are not applied (for example the limitation of the size of the PE to 25 mm² or 35 mm² depending on the type of conductor as specified in NF C 15-100).

Calculated values Visible in the calculation traces

The values given must be considered per source.

Calculation of the HV network resistance and reactance per phase Calculation of the resistance and reactance: standard NF C 15-100 Calculation of the resistance and reactance: standard IEC 60364 Transformer help

Protection of MV/LV transformers

Designing the protection conductor between the MV/LV transformer and the main low voltage switchboard (MLVS)

The conductors upstream of the main LV protection device are protected by the MV protection. They must be sized as per tables 2A and 2B, in the UTE C15-106 guide, produced on the basis of NFC 15-100.

My Ecodial L calculates only one transformer per circuit, i.e. the power rating taken into account is

HV network R Ph (mOhm) Equivalent resistance per phase of the high voltage network in mOhm

HV network X Ph (mOhm) Equivalent reactance per phase of the high voltage network in mOhm

Transformer R Ph (mOhm) Resistance per phase of the transformer in mOhm

Transformer X Ph (mOhm) Reactance per phase of the transformer in mOhm

Max lsc by source (kA) Maximum short-circuit current downstream from a transformer

Ib (A) Rated current of the transformer in A

See also



that of the transformer.

The size is calculated as a function of:

the rated power of the MV/LV transformers

the time required to clear the short-circuit current by the MV protection

the metal of the conductors and the type of insulation.

If protection is provided by an MV fuse, the breaking time is 0.2 seconds.



Sizing and protection of the conductor between the MV/LV transformer and the MLVS

Traditional circuit

My Ecodial L proceeds as follows:

using the power sum, My Ecodial L determines the operational current Ib at Q4

using the maximum short-circuit current, it selects a circuit breaker with sufficient breaking capacity, then a rating for the circuit breaker that is higher than Ib

My Ecodial L sets the thermal protection Irth for the circuit breaker such that Irth > Ib

My Ecodial L selects the conductor such that the theoretical permissible current Iz > Irth.

Conductor C4 is therefore sized taking into account the thermal setting for circuit breaker Q4 situated just upstream. This calculation principle is systematically applied by My Ecodial L.

Source circuit



To protect conductor C1 between the transformer and the main incoming device, My Ecodial L supposes that the MV protection upstream of the transformer protects C1 downstream of the transformer.

In that My Ecodial L is unaware of the thermal setting for protection device Q0, it proceeds as follows:

the operational current Ib at Q1 is assumed equal to the rated current InTR of the transformer (worst case)

using the maximum short-circuit current, it selects a circuit breaker Q1 with sufficient breaking capacity, then a rating for circuit breaker Q1 that is higher than Ib (i.e. = InTR)

My Ecodial L sets the thermal protection for circuit breaker Q1 such that Irth > Ib (= InTR)

My Ecodial L selects conductor C1 such that Iz>Ib (= InTR).

Conductor C1 is therefore sized taking into account the rating of the transformer, instead of the thermal setting of the MV protection device of the transformer. C1, oversized with respect to the real operational current, can handle increases in installation loads. The thermal protection for circuit breaker Q1 is also set for the transformer rating. This setting can be modified manually to adjust it to the real operational current at Q1, but this modification is the responsibility of the user.

Input parameters Transformer help

Fault current and equipotential connections for MV/LV transformers

In that the main equipotential connection is made in the MLVS, it is not necessary to take into account the impedance of the PE (or PEN in a TN-C system) between the source and the MLVS in the loop used to calculate the fault current. In My Ecodial L, this impedance is that of the source circuit (MV/LV transformer, generator or any other type of source).

See also



SLT = system earthing arrangement

Guide UTEC 15-105 § D.2.5.1 provides the equation for the fault current.

Where:

and are the resistance and reactance of the protection conductor from the main equipotential connection or the local connection to the start of the circuit under consideration

Cmin = 0.95

S is the size of the phases, is the size of the protection conductor

m = 1.05

and are the number of conductors for the phase and the protection conductor, respectively

and are the resistance and reactance of the source

and are the resistance and reactance of a phase conductor from the source to the start of the circuit under consideration

and are the resistance and reactance of the circuit upstream of the source



is equal to 1 in a TN system, 0.86 in an IT system without a neutral and 0.5 en IT in an IT system with a neutral

When calculating and , it is not necessary to take into account the connection between the transformers and the MLVS at which the equipotential connection is made.


Calculation of the resistance and reactance per phase for a High Voltage transformer

The values of 0.1 and 0.995 are those defined by the CENELEC R064-003 report (section 6.2) but can be modified via the RQ/XQ and XQ/ZQ characteristics. This modification causes a shift to manual mode for the component.


Calculation of the resistance and reactance of HV/LV transformers

See also

Un: Nominal phase to phase voltage downstream of the transformer

m: coefficient used to account for the transformer no-load voltage (m=1.05)

Psc: Short-circuit power of the HV network..

Zhv: Impedance of the HV network as seen from the LV network.

Rhv: Resistance of the HV network as seen from the LV network

Xhv: Reactance of the HV network as seen from the LV network.

See also



for NF C 15-100

This calculation depends on the operating mode:

1. automatic operation:

These values are not calculated. They are taken directly from tables CC and CD of the UTE C 15-105 guide

(§C.2.1.2.3 b) for a voltage of 400V. For other voltages, they must be multiplied by a coefficient

2. manual operation:

identical to standard IEC 60364, that is to say:


Calculation of the resistance and reactance of HV/LV transformers for IEC 60364

RT = Transformer resistance

XT = Transformer reactance

ZT = Transformer impedance

U = Network voltage

Ucc = short-circuit voltage (%)

ST = Rated power of the ransformer (kVA)

Pcu = Transformer copper losses (kW)

m = No-load factor = 1.05

I = Rated current of the transformer

See also

RT = Transformer resistance

XT = Transformer reactance

ZT = Transformer impedance




U = Network voltage

Ucc = short-circuit voltage (%)

ST = Rated power of the Transformer (kVA)

Pcu = Transformer copper losses (kW)

m = No-load factor = 1.05

I = Rated current of the transformer

See also



Generators

Input parameters

Most electrical installations contain loads that must be supplied even if the public electrical distribution system fails. This is either because they are part of a safety system (emergency lighting, booster pumps, smoke extractors, alarms, indicators, etc.) or because they are critical in nature and an extended shutdown would be dangerous to life and property or cause production losses.

One of the means commonly used to satisfy the need for continuous power consists of installing an engine generator set to restore power to priority loads, via one or more source changeover switches, in the event of a failure on the normal source.

However, use of two different sources generates an additional problem when choosing the protection devices for the priority circuits as they must be compatible with the characteristics of both sources.

My Ecodial L solves this problem by comprehensive calculations that ensure optimum sizing of the ac generator and the protection devices.

Some networks are supplied only by generators. This case is also treated by My Ecodial L.

Limitations Generators can be used in My Ecodial L as main or replacement sources. However, some configurations are prohibited.

See prohibited configurations and authorised configurations

In brief, all circuits must have at least one main source. Up to 4 parallel-connected generators can be used, provided they are all connected to the same busbars. A generator cannot be connected to a busbar trunking system.

As a replacement source, the generator can be connected to busbars other than the normal source busbars. This represents a subdivision of the network into priority circuits, connected to the replacement supply, and non-priority circuits, which are not powered during failures of the normal source. In this configuration, up to 4 replacement generators can be parallel-connected.

Priority circuits and non-priority circuits

Power failures mean that it is often necessary to provide a replacement source. However, sizing the replacement installation for the complete circuit can be expensive and pointless as some of the equipment is vital for safety or production whereas other less strategic equipment can be temporarily stopped without risk. The installation is thus divided into priority and non-priority circuits, thereby reducing the required capacity of the replacement source.

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AC generator short-circuit

Generator input parameters

See also

Description Content

Power Generator power in kVA (any value)

Earthing arrangement Earthing arrangement of the LV installation: TT - IT - TN-C - TN-S - Upstream (= that defined in the general characteristics)

Distributed neutral Neutral distribution for the LV installation: YES-NO (1)

Ph-Ph V (V) Nominal phase to phase voltage of the LV installation (2): 220-230-240-380-400-415-440-500-525-660-690 V

Network frequency (Hz) Frequency of the network 50 - 60 Hz

Power factor Cos phi at genset terminals (required to calculate voltage drop)



(1) For TN-C systems, the protective conductor (PE) and neutral are combined, thus the neutral is considered to be distributed.

(2) The calculation guide CENELEC R064-003 includes two nominal voltage coefficients:

Cmax equal to 1.05 to take into account the genset no-load voltage.

m equal to 1.05 for genset voltage fluctuations.

The CENELEC guide considers generators only as a replacement source for transformers. The guide does not consider calculation of the maximum short-circuit currents for generator applications and takes into account only the transient reactance and zero-sequence reactance, not the subtransient reactance.

My Ecodial L uses the subtransient reactance to calculate the maximum short-circuit currents for networks supplied only by generator.

To simulate the conditions of the CENELEC guide, the value of the subtransient reactance must be entered as the same value as the transient reactance (this is equivalent to not taking the subtransient reactance into account).

For a network with a main source and a replacement source, the voltages, frequencies,

x'o Zero-sequence reactance: 6% by default or manufacturer value

x'd Transient reactance: 30% by default or manufacturer value

x''d Subtransient reactance: 30% by default or manufacturer value

Neutral earthing electrode resistance RA (ohms)

Value of the neutral earthing electrode resistance in Ohms (any value)

Displayed for TT systems

ECP earthing electrode resistance RB (ohms)

Value of the ECP earthing electrode resistance in Ohms (any value)

Displayed for TT systems

IMD designationDesignation of the insulation monitoring device. Displayed only for IT systems. The possible IMDs can be accessed via a dropdown list with contents depending on the field of application and network voltage.

Field of application Field of application for choice of insulation monitoring device (IMD) for IT systems: Normal - Hospital



earthing arrangements and neutral distribution must be identical.

Calculated values Visible in the input grid

Visible in the calculation traces

The values given must be considered by source.

Generator help

Short-circuit across ac generator terminals

When a short-circuit occurs across the terminals of an ac generator, the current is first established at a relatively high value of around 3 to 5 ln (this is the "subtransient" period lasting from 10 to 20 ms), before decreasing (the "transient" period lasting from 100 to 300 ms) to stabilise (after 0.5 s) at a value which, depending on the type of regulation, can vary by roughly 0.3 or 4 times the nominal current of the ac generator.

There is a reactance corresponding to each of these three periods:

Subtransient (Xd’’): thus present for 10 to 20 ms after the start of the fault, used to check withstand to

electrodynamic forces and the breaking capacity of circuit-breakers for which the breaking time is greater than 10 or 20 ms.

Transient (Xd’): used to check withstand to conductor thermal stresses and the breaking capacity of circuit-

breakers for which the breaking time is greater than 10 or 20 ms.

Synchronous or permanent (Xd): to be considered after the transient period

Zero-sequence (Xo)

IMD reference Insulation monitoring device chosen for an IT system

Transient positive X'd (mOhm) Transient positive reactance (in mOhm)

Zero-sequence Xo (mOhm) Zero-sequence reactance (in mOhm)

Single-phase Xd (mOhm) Single-phase reactance (in mOhm)

Max lsc per source (kA) Maximum short-circuit current downstream of generator

Ib (A) Nominal current of the generator in A

See also



The reactances listed above can be obtained from the manufacturer. In the absence of more detailed information and according to the recommendations of the practical guide UTE C 15-500 (CENELEC R064-003), we shall take:

xd’ = 30 %, xo = 6 %

Similarly, we shall take the value of 20% for xd’’ (value not specified in the practical guide UTE C 15-500).

My Ecodial L calculates the various short-circuit currents as per standard NFC 15-105. The fact that in some cases a single-phase short-circuit current (Ik1) is obtained that is greater than the three-phase short-circuit current (Ik3) is normal and complies with the standard.

More info

ac generator with serial excitation or ac generator with compound excitation

For an ac generator with serial excitation, after the transient period (0.1 to 0.3 s), the short-circuit current is established at approximately 0.3 ln. This means that if the protection devices have not tripped during the subtransient or transient period, then the small value of the short-circuit current will not be sufficient to make them trip after.

To avoid this phenomenon, ac generators are used with compound excitation or over-excitation. In this case, the value of the short-circuit current after the transient period rises to approximately 3 ln, which is sufficient to trip the protection devices.

The large majority of ac generators are equipped with compound excitation. Consequently, the standard recommends carrying out short-circuit current calculations with the reactance Xd’: this is equivalent to considering that short-circuit current will not drop. My Ecodial L follows the recommendations of the standard and considers that the ac generators are equipped with compound excitation.

Generator help

Calculation example - Generator

"When calculating short-circuit and fault currents, the symmetrical components should be used to determine the characteristics of the generator (X'd transient, X''d sub-transient and Xo phase-sequence reactances).

Given that the CENELEC R064 003 report uses the impedance calculation method, the symmetrical components must be transformed into resistance and reactance values.

For a replacement genset, the most significant value is the minimum short-circuit current or the fault current. This is because the maximum short-circuit current is low. The transient reactance X'd is therefore the right choice.

The problem would be different if the gensets constituted the main source (e.g. the situation on a ship), in which case it would be necessary to select the X"d sub-transient reactance)."

Excerpt from an article in the J3E journal published by the Union Technique de l'Electricité, August/September 2003.

Note. My Ecodial L does not yet take into account the last point which will be included in a later version.

Equations

See also



Maximum three-phase short-circuit current Ik3max = Cmax.m.Uo/X'd, where:

Cmax is the maximum voltage factor = 1.05

m is the no-load factor = 1.05

Uo is the phase-to-neutral voltage (230 V)

X'd (mOhms) = Un² x'd / (100 P) Un is the phase-to-phase voltage (400 V) x'd is the transient reactance in % P is the rated power of the generator

Maximum single-phase short-circuit current Ik1max or fault current = Cmin.m.Uo/Zo, where:

Zo = (2.X'd+Xo)/3

cmin is the minimum voltage factor = 0.95

m is the no-load factor = 1.05

Uo is the phase-to-neutral voltage (230 V)

Xo (mOhms) = Un² xo / (100 P) Un is the phase-to-phase voltage (400 V) xo is the phase-sequence reactance in % P is the rated power of the generator

Application Consider a generator rated 500 kVA, where xd’ = 30%, xo = 6%

X'd = 96 mOhms

Xo = 19 mOhms

Zo = 70 mOhms

Therefore

Ik3max = 2.6 kA

Ik1max or If = 3.3 kA

The fault current is therefore the major value for a generator used as a replacement source.

Note that for a transformer with an equal rating, the short-circuit current is four times higher.

Return to previous page



Any source

This component is used to model sources. To see what types of circuits My Ecodial L can model using this component, consult types of circuits accepted and types of circuits refused .

Two selection windows must be filled in to allow the component to be treated by My Ecodial L. The main input data are the maximum three-phase short-circuit current (Ik3max) and the minimum single-phase short-circuit current (Ik1min).

Using these values, the characteristics of the impedances of the various supply upstream connections are defined, i.e. the phase, neutral and PE conductors, irrespective of the earthing system.

First entry window

Second window A second window follows depending on the choices made in the first window:

TT without neutral

TT with full neutral

TT with reduced neutral

TN-C with full PEN without incoming equipotential

TN-C with reduced PEN without incoming equipotential

TN-C with incoming equipotential

TN-S with undistributed neutral and without incoming equipotential

TN-S with undistributed neutral and with incoming equipotential

TN-S with full neutral and without incoming equipotential

Description Content

Un Ph-Ph(V) Nominal phase-to-phas voltage of the LV installation (2) 220-230-240-380-400-415-440-500-525-660-690 V

I service connection (A) Value of the current provided by the energy supplier.

Earthing arrangement TT - IT - TN-C - TN-S

Distributed neutral Indicates whether or not the neutral is distributed

Network frequency Two choices are possible: 50 Hz and 60 Hz

Energy supplier Characteristics accessible only for France. Two possible choices: private substation , EDF substation.

Page 1 of 28Any source


TN-S with full neutral and incoming equipotential

TN-S with reduced neutral and without incoming equipotential

TN-S with reduced neutral and incoming equipotential

ITSN (without neutral)

ITAN with full neutral

ITAN with reduced neutral

Examples

Short-circuit power factor

TT earthing arrangement

1. TT without neutral

1. Data

Uo

In

Cos PHI

Ik3max

Cos PHI SC

Rs

Rm

Figure 1: diagram upstream from point A in TT without neutral

Note on the earthing connection resistances



The neutral earthing connection resistance Rs, called in My Ecodial L, has in France, according to NFC 11 201, a total value of < 15 W. For the earth earthing connection resistance Rm, called in My Ecodial L, PROMOTELEC recommends a value of < 100 W. A test can be carried out and the user informed if the values entered are higher.

2. Calculations

2. TT with full neutral

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC

Rs

Rm



Figure 2: diagram upstream from point A in TT with full neutral

2.Checking

3. Calculations

Check My Ecodial L warning message

If Ik1min < In "The value of the single-phase short-circuit cannot be less than nominal current."

If "Upstream, neutral cross-section is less than phase cross-section. Check?"

If

"OK"

If

"Upstream, neutral earthing is close to the incomer. Check?"

If "The value of the single-phase short-circuit cannot be greater than the three-phase short-circuit. This data is replaced by the maximum value possible. "

(1)



(1): Taking the same short-circuit power factor (cos phi) for Ik3 and Ik1 leads to these calculation approximations.

3. TT with reduced neutral

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC

Rs

Rm

(1)



Figure 3: diagram upstream from point A in TT with reduced neutral

2. Checking

3. Calculations


Any source help

TN-C earthing arrangement

Check My Ecodial L warning message

If "The value of the single-phase short-circuit cannot be less than nominal current."

If "OK"

If


If "The value of the single-phase short-circuit cannot be greater than the three-phase short-circuit. This data is replaced by the maximum value possible."

(1)

See also



1. TN-C with full PEN without incoming equipotential

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC

Figure 4: diagram upstream from point A in TN-C with full PEN without equipotential

2. Checking

3. Calculations

Check Message displayed by My Ecodial L


If : "Upstream, PEN cross-section is less than phase cross-section. Check?"

If

"OK"





2. TN-C with reduced PEN without incoming equipotential

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC

Figure 5: diagram upstream from point A in TN-C with reduced PEN without equipotential

2. Checking

(1)

(1)



3. Calculations


3. TN-C with incoming equipotential

1. Data

Uo

In

Cos PHI

Ik3max

Cos PHI SC



If

"OK"


(1)

(1)



Figure 6: diagram upstream from point A in TN-C with incoming equipotential

2. Calculations

Any source help

TN-S earthing arrangement

1. TN-S with undistributed neutral and without incoming equipotential

1. Data

Uo

In

Cos PHI

Ik3max

If

Cos PHI SC

See also



Figure 7: diagram upstream from point A in TN-S with undistributed neutral and without equipotential

2. Checking

3. Calculations


2. TN-S with undistributed neutral and incoming equipotential


If "The value of the fault current cannot be less than nominal current."

If

"OK"

If

"The value of the fault curent cannot be greater than the three-phase short-circuit. This data is replaced by the maximum value possible."

(1)

(1)



1. Data

Uo

In

Cos PHI

Ik3max

Cos PHI SC

Figure 8: diagram upstream from point A in TN-S with undistributed neutral and equipotential

2. Calculations

3. TN-S with full neutral and without incoming equipotential

1. Data

Uo

In

Cos PHI

Ik3max



Ik1min

If

Cos PHI SC

Figure 9: diagram upstream from point A in TN-S with full neutral and without equipotential

2. Checking

3. Calculations




If

"OK"

If



If "The value of the fault current cannot be less than the nominal current."

If "OK"

If "The value of the fault current cannot be greater than the three-phase short-circuit. This data is replaced by the maximum value possible."




4. TN-S with full neutral and incoming equipotential

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC

(1)

(1)

(1)

(1)



Figure 10: diagram upstream from point A in TN-S with full neutral and equipotential

2. Checking

3. Calculations


5. TN-S with reduced neutral and without incoming equipotential




If

"OK"

If



(1)

(1)



1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

If

Cos PHI SC

Figure 11: diagram upstream from point A in TN-S with reduced neutral and without equipotential

2. Checking



If "OK"

If



If "The value of the fault current cannot be less than the nominal current."

If "OK"

"The value of the fault current cannot be greater than the three-phase short-



3. Calculations


6. TN-S with reduced neutral and incoming equipotential

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC

If

circuit. This data is replaced by the maximum value possible."

(1)

(1)

(1)



Figure 12: diagram upstream from point A in TN-S with reduced neutral and incoming equipotential

2. Checking

3. Calculations



If "OK"

If



(1)

(1)




Any source help

IT earthing arrangement

1. ITSN (without neutral)

1. Data

Uo

In

Cos PHI

Ik3max

Cos PHI SC

Figure 13: diagram upstream from point A in ITSN

2. Calculations

See also



2. ITAN with full neutral

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC

Figure 14: diagram upstream from point A with full ITAN

2. Checking




If

"OK"

If "The upstream transformer is close to the incomer. Check?"



3. Calculations


3. ITAN with reduced neutral

1. Data

Uo

In

Cos PHI

Ik3max

Ik1min

Cos PHI SC


(1)

(1)



Figure 15: diagram upstream from point A in reduced ITAN

2. Checking

3. Calculations


Si "The value of the single-phase short-circuit cannot be less than nominal current."

Si "OK"

Si

"The upstream transformer is close to the incomer. Check?"

Si "The value of the single-phase short-circuit cannot be greater than the three-phase short-circuit. This data is replaced by the maximum value possible."

(1)

(1)




Any source help

Examples

Example no. 1: LV rural utility network Let us model an incoming utility line used with a special tariff (e.g. French “blue” or “yellow” tariff ). See:

The diagram in figure 18,

Information from NFC 11 201 relating to neutral earthing in figure 19,

Installation of the transformer in figure 20.

The exact calculation gives:

Zq = 80 mW Rq = 53 mW Xq = 59 mW Ik3max = 3.2 kA cosPHIsc3 = 0.67

Zn = 42 mW Rn = 39 mW Xn = 16 mW Ik1min = 1.9 kA cosPHIsc1 = 0.77

Rs = 10 W Rm = 80 W If = 2.6 A

The values entered in My Ecodial L are:

Ik3max = 3.2 kA Ik1min = 1.9 kA cosPHIsc = 0.8 (as per IEC 947-2)

Rs = 10 W Rm = 80 W

My Ecodial L’s estimation from the values entered is:

Zq = 80 mW Rq = 64 mW Xq = 48 mW

Zn = 40 mW Rn = 32 mW Xn = 24 mW

The estimated results are relatively close to the exact values.

See also



Figure 18: Diagram of the LV rural utility network

Figure 19: Neutral earthing information from NFC 11 201

The neutral of the low voltage network is not earthed at the substation itself. It is earthed elsewhere on the LV network by one or more earth electrodes according to the recommendations of section 3.8, chapter 3 of the present standard. The resistance of the overall LV neutral earth circuit must not exceed 15 Ω (*).

These two earth circuits must be electrically independent (**) so that, in the event of a fault on the medium voltage network, the potential of the earth circuit used for the exposed conductive parts will not rise and affect the LV network.

This is achieved by maintaining a minimum distance between the earthing point of the exposed conductive parts and the nearest neutral earthing point. This minimum distance is 15 metres for soil with an average resistivity of less than 300 Ωm and 30 metres for ground with higher resistivity values.

3.8.1 LV lines

The neutral conductor of overhead lines exceeding a length of 100 m must be earthed at more than one point and the average number of earthing points must be at least one per 200 m. Each earth electrode must have a maximum resistance of 100 Ω. The total resistance of the earth electrodes is indicated in section 5.2.1.1.



Figure 20: 160 kVA transformer for LV rural utility network

Example no. 2: LV urban utility network Let us model an incoming utility line used with a special tariff (e.g. French “blue” or “yellow” tariff ), relatively close to the transformer. Refer to the diagram in figure 21.



The exact calculation gives:

Zq = 75 mW Rq = 30 mW Xq = 68 mW Ik3max = 3.4 kA cosPHIsc3 = 0.41

Zn = 11 mW Rn = 10 mW Xn = 4 mW Ik1min = 2.8 kA cosPHIsc1 = 0.49

Rs = 5 W Rm = 40 W If = 5.12 A

The values entered in My Ecodial L are:

Ik3max = 3.4 kA Ik1min = 2.8 kA cosPHIsc = 0.8 (as per IEC 947-2)

Rs = 5 W Rm = 40 W

My Ecodial L’s estimation from the values entered is:

Zq = 75 mW Rq = 60 mW Xq = 45 mW

Zn = 8 mW Rn = 6 mW Xn = 5 mW

The estimates are relatively close to the exact values, with the exception of R/X distribution due to an incorrect estimation of cosPHIsc.

Alternative concerning cosPHIsc:

cosPHIsc = 0.4 (data)

My Ecodial L’s estimation is then:

Zq = 75 mW Rq = 30 mW Xq = 68 mW

Zn = 8 mW Rn = 3 mW Xn = 7 mW

The estimates are relatively close to the exact values.

Figure 21: Diagram of the LV urban utility network

Any source help

Short-circuit power factor

See also



What if I don't know it ?

The user may not know the value of the short-circuit power factor at the point of connection. My Ecodial L can then choose the value defined in the circuit breaker short-circuit tests of standard IEC 947-2. Section 8.3.4 defines the value of the test circuit power factor as a function of the short-circuit level. For instance, for a short-circuit protective device such as a circuit breaker with an ultimate breaking capacity of 50 kA, the power factor under which the test is carried out is 0.2.

By using these very conservative values, My Ecodial L is sure to cover the worst case.

The user can use the values of this table as lower limits for the calculation assumptions.

Values of power factors corresponding to circuit breaker short-circuit test currents: Table 16, IEC 947-2 :

Effect induced by the discrete values of the short-circuit power factor

The values of table 16 are non-continuous. For instance, the power factor changes from 0.8 to 0.7 for a protective device designed for a short-circuit current of 4.5 to 5 kA.

However, the power factor is related to the calculation of the short-circuit current, indicating a possible edge effect.

This is demonstrated by:

where Z is more globally the impedance upstream of the point considered, i.e. upstream of the supply point of "any source".

Calculation of the upstream impedances as a function of the short-circuit level show that the values of Z are continuous. The method used by My Ecodial L now gives continuous and consistent results.

Test current (A) Power factor

I<=1500 0.95

1500 < I <= 3000 0.9

3000 < I <= 4500 0.8

4500 < I <= 6000 0.7

6000 < I <= 10 000 0.5

10 000 < I <= 20 000 0.3

20 000 < I <= 50 000 0.25

50 000 < I 0.2



Graph 17 : Upstream impedances as a function of Ik3max

Any source help

See also



Upstream project references

Presentation Upstream project references are used to connect together two networks. In this configuration, the upstream network, represented by the upstream project reference circuit, is considered to be the normal source of the downstream network to which it forwards the following characteristics:

voltage

earthing arrangement

type of network (single-phase or three-phase, with or without neutral)

impedances

voltage drop

However, the selected protection devices are not forwarded to the downstream project. Consequence: no cascading or discrimination is possible between the two networks.

Moreover the busbars to which the upstream project reference circuit are connected are considered to be the mains LV switchboard (MLVS). It is therefore possible to connect a capacitor bank.

Note:

This component was introduced to overcome the limitation of My Ecodial L to 75 circuits. This limit was eliminated with version 3.3 but the component was conserved to maintain compatibility with older versions.

Input parameters

Description Content

Upstream project Name of file containing the upstream network. This file must be in the same directory as the current project. The project must be completely calculated with the same software version as the downstream project.

Upstream circuit Name of the upstream network circuit to which the downstream network is connected.

Retrieve upstream calculations

Two choices are possible:

No, to retrieve the characteristics of the upstream project.

Yes, to conserve the values entered in the downstream project.

Notes:

- If either of the two input parameters above is modified, this parameter is automatically set to Yes.

- If one of the characteristics of the upstream project transmitted to the downstream project has been modified, the downstream project is automatically updated when the calculation is

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Capacitors

Input parameters

Limitations First of all, My Ecodial L only deals with 3-phase capacitor banks, which corresponds to most power factor correction (or reactive energy compensation) applications.

With respect to earthing arrangements, My Ecodial L does not deal with TN-C arrangements or IT with neutral arrangements. It therefore imposes a TN-S arrangement if the user requests a TN-C arrangement and an IT arrangement without neutral if the user requests an IT arrangement with neutral. Note that since most capacitors operate with three phases and no neutral, the TN-S arrangement represents a viable and more economical solution than a TN-S arrangement.

Finally, with respect to the location of capacitor banks, My Ecodial L only deals with overall reactive energy compensation in which capacitor banks are installed at head of the installation, and not with local or individual compensation. See location of banks

Reactive energy Electrical energy consists of active energy and reactive energy. Active energy (kWh) results from the active power P (kW) of the loads. It is fully converted into mechanical power (work) and heat (losses). The reactive energy consumed (kvarh) is used to supply the magnetic circuits of the electrical machines. It corresponds to the reactive power Q (kvar) of the loads.

Apparent energy (kVAh) is the vector sum of the two energies mentioned above. It corresponds to the apparent power S (kVA) of the loads.

Reactive energy consumers are inductive devices (asynchronous motors, fluorescent light ballasts, static inverters, etc.)

Circulation of reactive energy has major technical and economic consequences. This is because the greater the reactive power, the more apparent power and thus current must be supplied for the same reactive power. This greater drawn current results in overloads at transformer level, supply cable temperature rise, additional losses, large voltage drops and, for the electricity producer, more current to be supplied.

The graph shows that for the same useful or active power, the greater the reactive energy drawn (case corresponding to Q2), the greater the apparent power S2. To reduce the apparent power drawn from the network from S2 to S1, we must connect a capacitor bank to supply reactive energy Qc, such that: Qc = P * (tan phi2 - tan phi).

To encourage compensation of reactive energy consumption and avoid oversizing the network, the electrical utility applies penalties to consumers who overrun a certain threshold of reactive energy consumption.

Page 1 of 10Capacitors


Capacitors sizing

Capacitors are sized according to the required power factor (cos phi) and to network voltage and frequency. This is because the reactive energy supplied by the capacitor is equal to:

Q = w x C x U2

where Q = reactive energy (kvar)

C = Capacitor capacitance (Farads)

w = angular frequency in radians per second (w = 2p f where f is the frequency in Hertz)

U = voltage across capacitor terminals

Location of banks Choice of compensation type SAH type banks Harmonics problems Examples of installations with harmonic pollution Problem of transient switching conditions

Capacitor input parameters

Input parameters

Calculated values Visible in the input grid

Capacitor help

Choice of capacitor bank location

See also

Description Content

Pre-compensation power factor

Value of overall cosphi of the installation before power factor correction

Value calculated and entered automatically from the power sum

Required global power factor Value of cosphi after power factor correction

Value entered in the general characteristics of the network

Harmonics power Sum of the powers in kVA of all non-linear loads (free value)

Reactor turning order Resonance frequency of the L-C assembly. It must be chosen in such a way that remote control frequencies are not disturbed.

Earthing arrangement TT - IT - TN-C - TN-S - Upstream (=upstream earthing system)

Power (kvar) Power of the capacitor bank to be installed in kvar

Ib (A) Nominal current in A

Compensation type Type of bank to be used: Classic - Comfort - Harmony

Regulation (kvar) Number of compensation steps x unit power of each step

See also



There are three possible locations. My Ecodial L only treats overall compensation, which is why capacitor banks must be installed at the head of the installation.

Overall compensation

The bank is connected at the incoming end of the installation and ensures reactive energy compensation for all loads. It is suitable when the main aim is to eliminate penalties and relieve the transformer substation.

2 other locations, not treated by My Ecodial L, however exist:

Local or sector compensation

The bank is installed at the head of the installation sector to be corrected. It is suitable when the installation is large and contains workshops with different load conditions.

Individual compensation

The bank is connected directly to the terminals of each inductive load (in particular, motors). It must be considered when motor power is a major part of the subscribed power. This compensation is technically ideal as it produces reactive energy at the very point where it is consumed, and in quantities adjusted to the demand. Economically speaking, this solution requires a greater initial investment.

Example of motor compensation Capacitor help

Choice of compensation type

Fixed compensation The capacitor bank is either on or off. This compensation type is used when reactive power is low (< 15% of transformer power) and the load relatively stable.

Automatic or stepped compensation The capacitor bank is divided into steps, with the possibility of switching in the required number of steps, normally automatically. This compensation type is usually installed on the incoming end of the LV distribution network or of a large sector. It allows step by step regulation of reactive energy.

Choice according to network harmonic pollution level Choice table according to harmonic level

See also

Gh/Sn <= 15% Standard network installation type Classic capacitors

15% < Gh/Sn <= 25% polluted network installation with type Comfort capacitors



Sn= transformer power kVA

Gh= total power of harmonic generators kVA

The Classic type is suitable for networks with low levels of harmonics.

The Comfort type satisfies polluted network criteria.

The Harmony type (association of a capacitor and a detuning reactor) will withstand very polluted networks..

My Ecodial L handles all 3 of the above cases.

For even higher power values of harmonic generators, special treatment of harmonics is normally required. The appropriate device (harmonic filter) performs both reactive energy compensation and harmonic filtering functions. My Ecodial L does not handle this last case.

My Ecodial L automatically imposes a type of bank (Classic, Comfort, or Harmony) according to network pollution level. If network pollution is too great and requires use of filters, My Ecodial L returns a warning message and stops the calculation.

SAH type banks Harmonics problems Examples of installations with harmonic pollution Problem of transient switching conditions Capacitor help

Harmony (detuned reactor) type capacitor banks

Harmony bank (principle)

25% < Gh/Sn <= 50% highly polluted network installation with type Harmony capacitors

Gh/Sn > 50% highly polluted network Filters

See also



For severely polluted networks, the use of Harmony type capacitor banks is recommended. They are made up of detuned reactors combined with oversized capacitors.

Capacitor help Choice of compensation type

Motor compensation

The power factor (cos phi) of a motor is normally:

extremely low on no-load and on small load

and low in normal operation.

It is thus a good idea to install capacitors for this type of load to compensate for reactive power consumption and increase the power factor of the installation.

When a motor drives a load with high inertia, it may, after interruption of the supply voltage, continue to run using its kinetic energy and be self-excited by a capacitor bank installed at its terminals.

The capacitors supply the motor with the reactive energy it needs to operate as an asynchronous generator. This self-excitation maintains voltage and can lead to high overvoltages.

To prevent dangerous overvoltages due to self-excitation phenomena, you must ensure that capacitor bank power satisfies the following equation:

Io: motor no-load current.

Io can be estimated by the following expression: Io = 2 In ( 1 - cos ϕ n ), where ϕ n is the nominal cos ϕ

Un: nominal phase-to-phase voltage

Qc: capacitor bank power

Capacitor bank location

Thermal sizing of equipment

The permissible variations in the value of fundamental voltage and harmonic components may lead to a 30 to 45% current increase in the capacitors. Variations due to tolerances on capacitor capacitance can result in an additional 15% increase (as per standard NFC 15-104). For Rectiphase capacitors, this additional increase is limited to 5 %.

The cumulated effect of these two phenomena means that equipment must be sized for the following currents:

1.36 times the rated current for standard capacitor banks (Classic type)

1.5 times the rated current for Rectiphase reinforced capacitor banks (Comfort type)

1.12 times the rated current for Rectiphase capacitor banks protected by reactors (Harmony type) with a tuning order of 2.7



See also

See also

See also



Capacitor help

Harmonics problems

Some non-linear devices are responsible for the circulation of harmonics on the network. For example, power electronics equipment (variable speed drives, diode rectifier bridges, thyristors or transistors, inverters or switch mode power supplies), loads using electric arcs (arc furnaces, welding machines), lighting (discharge lamp ballasts, fluorescent lights and, finally, to a lesser extent, equipment with magnetic circuits such as AC generators and transformers.

These harmonics disturb the operation of many electronic devices and machines. In particular, capacitors are extremely sensitive to them as their impedance decreases in proportion to the harmonic number of the harmonics present. If the natural frequency of the capacitor-network assembly is close to a harmonic number, resonance will occur, amplifying the corresponding harmonic. In this particular case, the resulting current will cause temperature rise and then disruptive breakdown of the capacitor. Solutions are available to limit these risks and ensure proper operation of the capacitors.

To deal with this phenomenon, a variety of capacitor bank types are used (see the table on choice of compensation type): Classic, Comfort, Harmony (with detuning reactors), or if the network has an extremely high level of harmonic pollution, filters. My Ecodial L takes harmonics problems into account. According to the network pollution rate, it imposes a type of capacitor (Classic, Comfort, or Harmony). However, My Ecodial L does not handle filters.

For more details on harmonics problems, see Merlin Gerin “Cahier Technique” publication no. 152


Problem of transient switching conditions

Switching of a capacitor bank is accompanied by transient current and voltage conditions. Overcurrents and overvoltages appear, the amplitude and frequency of which depend on the characteristics of the upstream network and the number of capacitor banks (fixed or stepped banks). As a rule, pre-insertion resistances, used to limit the switching inrush current, are installed by the manufacturer

My Ecodial L does not take into account problems relating to transient conditions for capacitor banks.

See also



In this matter, you can also consult « The Low Voltage Expert Guide » no. 6 p. 8 to 12.


Installation examples

Example of an installation with a low level of harmonics: Classic capacitors can be used for compensation.

See also



GH / Sn = 15%

Harmonic voltages on 400 V busbar

Total harmonic distortion THD(U) = 3%

RMS voltage at capacitor terminals = 432 V

Choice of bank:

Classic capacitors.

Voltage Un = 400 V given that capacitor limit = 1.1 Un = 440 V.

Results


Example of a polluted installation: Comfort type capacitors can be used for compensation.



GH / Sn = 20 %

Harmonic voltages on 400 V busbars



Choice of bank:

Comfort type capacitors.

Voltage Un = 440 V given that capacitor limit = 1.1 Un = 484 V.

Results


Example of a very polluted installation: Harmony type capacitors can be used for compensation.



GH / Sn = 50%

Harmonic voltages on 400 V busbars



Choice of bank:

Harmony type capacitors

voltage Un = 440 V given that capacitor limit = 1.1 Un = 517 V

combined with a 190 Hz tuned detuning reactor.

Results

Total harmonic distortion THD(U) = 3.4%


See also



Busbars

The switchboard houses the switchgear, controlgear and other distribution components of the electrical installation. It consists of a number of parts known as functional units. Each functional unit includes all the mechanical and electrical parts required to carry out a given function. The switchboard has a major influence on the overall dependability of the installation. Consequently, the type of switchboard must be perfectly suited to its application. It must be designed and manufactured in compliance with applicable standards and standard working practice.

The switchboard enclosure offers two types of protection:

Protection of the enclosed devices against vibrations, mechanical shocks and other external factors

Protection of people against electric shocks

The reference standards for switchboards in France are NFC 61 - 910, NF C63 - 410 and NF C 63 - 412. The reference standard from the international viewpoint is IEC 439-1, which defines the conditions for producing Type Tested Assemblies (TTA) and Partially Type Tested Assemblies (PTTA).

My Ecodial L distinguishes between two types of busbars:

Uncalculated (fictitious) busbars

Uncalculated busbars (zero impedance) are used to represent tap-offs under a given circuit. These busbars are fictitious and are simply a means to represent a number of outgoers on a given tap-off.

To place uncalculated busbars, position a "busbar" circuit on the diagram, then modify the circuit if necessary to transform the calculated busbars into a tap-off.

Calculated busbars

Input parameters

These busbars represent all types of switchboard (main LV board, secondary boards, final distribution boards, control and monitoring boards).

Calculable busbar input parameters

Description Content

Busbar range:

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Calculated values

Busbar type

Prisma Linergy: Linergy range busbars for Prisma switchboard

Prisma on edge – Prisma flat: Busbars for Prisma switchboard

Standard on edge – Standard flat: Copper with standard dimensions

Customised on edge – Customised flat: dimensions to be completed by the user

Okken

For more details on the busbars of the Merlin Gerin Prisma range, consult the catalogue.

In(A) Nominal current of the busbar. If the value is zero, My Ecodial L will look for the thermal setting of the upstream protection device. If the value is entered by the user, My Ecodial L will check consistency with the thermal setting of the upstream protection device.

Length Busbar length

Number of bars in parallel Number of parallel-connected busbars

Thickness (mm) Busbar thickness in mm (5 mm as standard)

Width (mm) Busbar width in mm

Power factor Power factor at busbar level

Circuit polarity Polarity of busbars: 3P + N or 3P or 2P or 1P or Upstream (= same as upstream circuit).

Ambient temperature Ambient temperature outside the switchboard

Max permitted T°C on Isc Maximum temperature accepted for Isc

Protection level Degree of protection of enclosure: <= IP30 or >IP30

Earthing arrangement TT - IT - TN-C - TN-S - Upstream (= that defined for the upstream circuit)

Metal Type of metal: Copper or Aluminium (Aluminium for a customised busbars only)

Phase to earth fault max. breaking time

Standards stipulates a breaking time such that the fault is eliminated in less than 5s. In some cases a 5s breaking time is permitted, particularly for primary networks.

Description Content

Page 2 of 3Busbars


Busbar help

Available l (A) Busbar nominal current

R (mOhm) Resistance per phase

X (mOhm) Reactance per phase

Peak lsc (kA) Peak short-circuit current

Max lsc (kA) Maximum short-circuit current

Connection dU (%) Voltage drop in the busbars

See also

Page 3 of 3Busbars


Busbar trunking systems

Input parameters

Busbar trunking systems (BTS) offer easy implementation, flexibility and a number of possible connection points.

Busbar trunking systems require special treatment from My Ecodial L and some configurations cannot be dealt with. For more details, consult accepted circuits with BTSsand refused circuits with BTSs.

With cables, the cost of modifications varies considerably according to the distance between the switchboard and the point of use. When modifications are likely to be frequent, busbar trunking systems offer a number of advantages.

Busbar trunking systems are dealt with in standard NF C 63-411. Guide UTE C 15-107 gives the conditions for determining the characteristics of busbar trunking systems and choosing the protection devices. For more details!

Due to their diversity, busbar trunking systems can be used to distribute electrical power from the output of the HV/LV transformers right on through to the loads.

There are three main categories:

Busbar trunking systems for the transformer / main LV switchboard connection: This connection is designed for the transformer power rating and its installation is virtually permanent and unchangeable. It has no tap-offs. Extensively used for short connections, it is widespread beyond ratings of 2000 / 2500 A. Standard NF C 15-100 (§523.6) requires use of busbar trunking systems for cases involving more than 4 parallel-connected cables (§ B 5.2). For more details!

Busbar trunking systems for distribution: these can be very variable in size and are used to: Perform distribution along a main line. Supply other subdistribution or final distribution conductors, which require a high degree of flexibility. Supply load points directly. For more details!

Prefabricated installation systems for final distribution (NF C 61-306): These trunking systems comprise the conductors allowing rapid connection of 10/16 A socket outlets at specific points. They ensure horizontal and vertical distribution by means of plinths or columns and can convey energy as close as possible to the installation thanks to a functional and attractive design. They can include other circuits with the corresponding outlets (telephone, computer network, bus, etc.). Flexibility of use combined with great adaptability to changing needs justifies their use in final distribution.

BTS sizing principles BTS overload sizing BTS voltage drops BTS minimum short-circuit currents Checking the BTS in automatic and manual mode Calculation of BTS max lsc

Busbar trunking input parameters

See also

Description Content

Application distribution - rising main - standard lighting - strip lighting. This characteristic is not displayed if the BTS is of the feeder or final distribution.

Does it support the luminaires? yes - no Displayed for standard lighting applications. It is used to orient the search toward a flexible BTS (KDP range)

Number of circuits 1 -2 Orients the choice towards a BTS offering two circuits or ribbon cables (KBB range)

Type of tap-off Bolt-on tap-off units - Plug-in tap-off units Displayed for rising main and distribution applications

Load distribution Load calculation method: Uniform distribution - Non-uniform distribution Displayed for rising main and distribution applications

Isc max for chosen break. cap. Head end - The tap off. Displayed for rising main and distribution applications

Designation Busbar trunking model

Ib (A) Busbar trunking operational current

Length (m) Length of busbar trunking in metres

Required IP Degree of protection: IP20 - IP31 – IP54 – IP55 – IP66

Spacing Distance between luminaire centres. Displayed for standard lighting or strip lighting applications. Two possible choices: <= 3m or > 3m

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BTS help contents

BTS sizing principle

Conductor metal Copper - aluminium

PE type standard - isolated - reinforced

User-defined K User-defined coefficient

Line max. Delta U (%) Maximum voltage drop authorised for the busbar trunking

Earthing arrangement TN-C – TN-S – TT – IT – Upstream

THDI (%) Total harmonic distortion of the current.

More info

Installation Installation method: Standard - On the side - Vertical

Ambient temperature (°C) Ambient temperature around the busbar trunking

Downstream circuit polarity Circuit polarity 3P + N – 3P – 2P – 1P – upstream

See also



Parameters used to calculate the BTS

Retrieval of all upstream characteristics:

Short-circuit current at start of connection

Permissible maximum current

Voltage

Voltage drop

Neutral protection level

Entering user parameters

Type of load: uniform or non-uniform distribution or feeder / transmission

Installation method

Calculation method

Length

Conductor metal

PE type

Degree of protection

Choice of the most unfavourable case

According to the type of circuit (main or replacement), the most restrictive values are used in the calculations.

BTS voltage drops

Consideration of voltage drop on start-up Consideration of voltage drop in normal operation

Consideration of voltage drop on start-up In the event of a final connection with a motor, My Ecodial L treats the transient case of voltage drop on start-up. My Ecodial L calculates the voltage drop on start-up and compares it to the maximum voltage drop stipulated by the standard. In automatic mode, if the voltage drop threshold is overrun, My Ecodial L will choose another BTS so as to comply with the requirement of the standard. In manual mode, the calculation will be stopped and the user must choose another BTS.

The calculation method used by My Ecodial L 3 is described below.

See also



Variables Comments

dUDemarrage Total voltage drop on motor start-up

dUAmont Voltage drop for the upstream circuit

dU Voltage drop of the connection on start-up

SEUIL Upper limit of the voltage drop on start-up

DU(i) Voltage drop on tap-off number i of the BTS with any load

Idem Starting current

I(i) Tap-off current of the BTS with any load

Uo Voltage

L Length of the BTS with distributed load

L(i) Length of the BTS with any load

Cos Cos phi on start-up

Sin Sin phi on start-up

r Linear resistance given by the standard

x Linear reactance given by the standard



Return to top of page

Consideration of the connection voltage drop The standard stipulates that the total voltage drop from the source up to the point furthest from the installation must be less than a given threshold. My Ecodial L allows the user to distribute voltage drop over all the connections by entering a user threshold.

In the automatic mode, My Ecodial L calculates the connection voltage drop and compares it to the maximum voltage drop stipulated by the user. According to the result, My Ecodial L may have to choose another BTS in order to comply with this requirement.

My Ecodial L calculates total voltage drop and compares it to the standard threshold.

K K = Kpoldu x Kcharge where Kpoldu is a coefficient depending on polarity and Kcharge =

Variables Comments

dUCumule Total voltage drop

dUAmont Voltage drop for the upstream circuit

dU Voltage drop of the connection on start-up

SEUILLIAS Upper limit of the voltage drop




Return to the BTS help contents

BTS minimum short-circuit currents

Consideration of the Phase to Phase min lsc current Consideration of the Phase to Neutral min lsc current Consideration of the Phase to Earth min lsc current

Consideration of the Phase to Phase min lsc When a short-circuit occurs, a strong current passes through the conductors, bringing them to a high temperature. The operating time of the protection device must be compatible with the permissible thermal stresses of the upstream circuit conductors.

My Ecodial L calculates the minimum short-circuit currents and ensures compliance with these requirements according to the standard.

Compliance with the requirements laid down in the standard for protection may lead to another choice of busbar trunking.

The details of the method used by My Ecodial L 3 are given below:

SEUILCUMUL Upper limit of the total voltage drop

DU(i) Voltage drop on tap-off number i of the BTS with any load

IB Operational current

I(i) Tap-off current of the BTS with any load

Uo Voltage

L Length of the BTS with distributed load

L(i) Length of the BTS with any load

Cos Cosine phi on start-up

Sin Sine phi on start-up

r Linear resistance given by the standard

x Linear reactance given by the standard

K K = Kpoldu x Kcharge where Kpoldu is a coefficient depending on polarity and Kcharge = if any load, else 0.5.

See also



Variables Comments

Iccminph Phase to phase minimum short-circuit current

Tf Blowing time of the fuse (if applicable) or of the protection device in general

Cmin Constant = 0.95

Uo Voltage

RbPhMin Minimum phase to phase loop resistance. This is the sum of the minimum upstream phase resistance and of the resistance derived from the manufacturer table corresponding to the chosen BTS

XbPhMin minimum phase to phase loop reactance. This is the sum of the minimum upstream phase reactance and of the reactance derived from the manufacturer table corresponding to the chosen BTS

Coef Fuse blowing loop coefficient

Expo Fuse blowing loop coefficient

Thermal stress

Permissible thermal stress. Characteristic of the chosen BTS

Irm Magnetic setting

Irth Thermal setting current



If My Ecodial L does not find a busbar trunking system quickly enough, it will stop searching and display an error message in the calculation screen.

Another busbar trunking system is chosen by imposing a lower impedance. Consequently, the short-circuit current is lower and the requirements are easier to comply with.


Consideration of the Phase to Neutral min lsc When a short-circuit occurs, a strong current passes through the conductors, bringing them to a high temperature. The operating time of the protection device must be compatible with the permissible thermal stresses of the upstream circuit conductors.

My Ecodial L 3 calculates the minimum short-circuit currents and ensures full compliance with these requirements according to the standard.



If there is a neutral

Variables Comments






Consideration of the Phase to Earth min lsc When a short-circuit occurs, a strong current passes through the conductors, bringing them to a high temperature. The operating time of the protection device must be compatible with the permissible thermal stresses of the upstream circuit conductors.

My Ecodial L 3 calculates the minimum short-circuit currents and ensures full compliance with these requirements according to the standard.

Circuit-breaker magnetic settings guarantee breaking of a minimum current on a short-circuit in order to guarantee protection of persons.



Iccminne Phase to neutral minimum short-circuit current



Uo Voltage

RbNeMin Minimum phase to neutral loop resistance. This is the sum of the minimum upstream neutral resistance and of the resistance derived from the manufacturer table corresponding to the chosen BTS

XbNeMin Minimum phase to neutral loop reactance. This is the sum of the minimum upstream neutral reactance and of the reactance derived from the manufacturer table corresponding to the chosen BTS



Thermal stress






Variables Comments

Idéfaut Phase to earth minimum short-circuit current, also known as fault current



alpha

Earthing arrangement alpha

IT with neutral 0.5

IT without neutral

TT, TN-C and TN-S 1

Uo Voltage

RbPeMin Minimum phase to earth loop resistance. This is the sum of the minimum upstream earth resistance and of the resistance derived from the manufacturer table corresponding to the chosen BTS

XbPeMin Minimum phase to earth loop reactance. This is the sum of the minimum upstream earth reactance and of the reactance derived from the manufacturer table corresponding to the chosen BTS







BTS help contents

Calculation of BTS max lsc

My Ecodial L calculates the maximum short-circuit currents

three-phase: IK3MAX

two-phase: IK2MAX

single-phase: IK1MAX

using the following formulas:

This calculation is not directly used for choosing a busbar trunking system, but is performed in this case on the connection so that it can be considered for the sizing of downstream circuits.

Return to the BTS help contents

BTS overload sizing

My Ecodial L chooses a busbar trunking system that satisfies the overload condition:

Its rated current or thermal setting current lr must be at least equal to circuit operational current Ib:

The rated current of the busbar trunking must be at least equal to:


Thermal stress




See also

Uo:Voltage

Cmax: Constant = 1.05

RKMAX = Upstream resistance + Resistance characteristic of the BTS (taken from the manufacturer table)

XKMAX = Upstream reactance + Reactance characteristic of the BTS (taken from the manufacturer table)

See also



where f is a coefficient based on the ambient temperature and installation method and k is a factor depending on the protection device.

BTS search criteria:

Conductor metal

In according to installation method: horizontal, edgewise, vertical

Ambient temperature

Level of neutral protection

The application (lighting, motor, high density distribution, etc.)

When My Ecodial L has chosen a BTS, it retrieves all its characteristics via a table from the standard:

Permissible thermal stress for each conductor.

Loop, phase, neutral and earth resistivities and reactances.

Part numbers of the busbar trunking.

Thus, at the end of this BTS calculation, My Ecodial L has chosen the first busbar trunking complying with the overload requirement.

BTS help contents

Checking the BTS in automatic and manual mode

Checking overloads Checking thermal stress and magnetic setting Checking voltage drop requirements Checking withstand to electrodynamic forces

Checking BTS overloads For manual and automatic calculation alike, My Ecodial L makes no modifications in this part of the program; it only carries out a check.

My Ecodial L checks that:

the chosen BTS exists

the BTS accepts a TN-C earthing arrangement"

the BTS accepts a half neutral

the permissible ambient temperature is correct

the busbar trunking rating is sufficient

and warns the user if the requirements of the standard are not complied with

Checking BTS min lsc For manual and automatic calculation alike, My Ecodial L makes no modifications in this part of the program; it only carries out a check.

Just as in the "calculation of minimum ISC magnetic setting and thermal stress", My Ecodial L calculates the minimum short-circuit currents, protection times and thermal stresses that can be accepted for the chosen busbar trunking. My Ecodial L checks the requirements stipulated by the standard. If they are not complied with, My Ecodial L warns the user in the calculation page but does not choose another BTS .

My Ecodial L checks all the requirements linked to minimum phase to phase, phase to neutral and phase to earth short-circuit currents.

Checking BTS voltage drops For manual and automatic calculation alike, My Ecodial L makes no modifications in this part of the program; it only carries out a check.

My Ecodial L recalculates the voltage drops calculated in the « voltage drop » section for the busbar trunking chosen at this stage and compares it to the thresholds laid

See also



down by the standard and by the user.

If the test shows that the requirements of the standard are not complied with, a message is displayed in the calculation page (the trace).

Checking BTS electrodynamic forces To ensure that the busbar trunking withstands the electrodynamic forces, the standard stipulates that the peak short-circuit current must be at least equal to the maximum current that can flow through the conductors multiplied by a peak factor for which the values are given by the standard according to the current considered. My Ecodial L takes this requirement into account.




Cables

Input parameters Cable cross-section calculation principle Variables used to size a cable Phase cable cross-section calculation method (IEC standard) Phase cable cross-section calculation method (NFC standard) Neutral cross-section calculation method PE cross-section calculation method Calculation of total coefficient k (IEC standard) Calculation of total coefficient k (NFC standard) Calculation of voltage drops Calculation of minimum short-circuit currents and verification of thermal stress Calculation of maximum short-circuit currents and verification of magnetic stress

Cable input parameters


Description Content

Length (m) Cable length in metres

Installation method Cable laying method as per standard. Access to selection guide by double-clicking the data entry cell.

Insulation

Conductor insulation family:

PR family: elastomer insulated cables

PVC family: polyvinyl chloride insulated cables

Rubber family: rubber insulated cables

Conductor type Type of conductor: Multi-pole - single-pole - Insulated conductor

THDI (%) Total harmonic distortion of the current.

More info

Conductor arrangement

Conductor arrangement:

Trefoil

Flat touching

Flat spaced (spacing > than 1 cable diameter)

This characteristic is used to set the linear reactance value (between 0.08 and 0.13).

Page 1 of 25Cables

5/6/2011file://C:\Users\noor\AppData\Local\Temp\~hh1A36.htm

The user coefficient (user-defined K) is used to modify the k coefficient derived from the installation method and the environment of the calculated circuit. This parameter can for example be used to oversize cable cross-sectional area in order to allow for subsequent circuit extensions or an explosion hazard. In this case, the K will be set at a value between 0.01 and 1. It will be multiplied by the coefficient derived from the installation method and the

It is displayed only for multi-conductor cables.

PE type Type of protective conductor (separate PE - included PE - bare PE)

"Included PE" is proposed only for multi-conductor cables.

Thermal resistivity of the ground (Km/W)

Thermal resistivity of the ground. This characteristic is only visible for buried installation methods. The values proposed are those of the installation standard.

No. of additional touching circuits Number of additional touching circuits (not counting the circuit being calculated)

No. of layers Number of layers (NF C 15-500, table 52O)

No. of trays Number of trays (IEC 60364, table A.52-20 and A.52-21)

User-defined K User coefficient, between 0.01 and 1

Ambient temperature (°C) Ambient temperature (°C)

Line max. Delta U (%) Maximum voltage drop authorised for the circuit being calculated

Start-up U max. Maximum voltage drop authorised during motor starting. This characteristic is only visible for cables upstream of a motor with a starting system other than a variable speed drive (direct-on-line, star-delta, smooth).

Designation Designation of the cable used

No. of Ph conductors Number of conductors per phase

Ph conductor S (mm²) Standardised cross-section of a phase conductor in mm²

No. of N conductors Number of neutral conductors (N)

N conductor S (mm²) Standardised cross-section of a neutral conductor in mm²

No. of PE conductors Number of protective conductors (PE)

PE conductor S (mm²) Standardised cross-section of a protective conductor in mm²

Ph conductor metal Phase conductor core metal (Copper - Aluminium)

Neutral conductor metal Neutral conductor core metal (Copper - Aluminium)

PE conductor metal PE conductor core metal (Copper - Aluminium)

Page 2 of 25Cables


environment of the circuit considered, thus increasing the resulting cross-sectional area by the same amount. For more details

Examples of use:

10% power reserve : K= 0.9

Remarks and Ecodial behaviour The cross-sections and number of conductors can be overridden by the user. For more details on limits of use of the manual mode see " limits in manual mode".

The cross-section of the neutral conductor depends, among other factors, on the choice made by the user in the general characteristics.

If choice of N cross-section = Ph cross-section is YES, neutral cross-section will be equal to phase cross-section. Otherwise, the neutral conductor cross-section will be calculated as half that of the phase.

For a network with undistributed neutral, the neutral conductor cells of the table are filled with the symbol "-" to indicate "not applicable".

For a TN-C earthing arrangement, the neutral (N) and protective conductor (PE) are combined: My Ecodial L will indicate PE(N) in the neutral conductor cell of the table.

Standard NFC15-100 (2003 version) no longer uses the notion of a loaded neutral. This case is now dealt with by the level of harmonic distortion (THDI) entered elsewhere.

Manual choice of cables – behaviour and limits of My Ecodial L

General behaviour In automatic mode, My Ecodial L chooses the cross-section and the number of conductors according to an algorithm which is optimum in most cases

In some cases, the user may wish to override one or more characteristics: the number of conductors by phase, the type of metal or insulation, etc. My Ecodial L then changes to manual mode.

Always remember, when manual override values are set, My Ecodial L checks for conformity with indirect contact protections rules (for the protection of persons) and checks the voltage drop. My Ecodial L chooses the protection devices and sets them accordingly. This version of My Ecodial L does not optimise conductor size when the number of conductors is imposed. For example, My Ecodial L cannot currently choose the best possible cable size when 2 cables per phase is imposed.

For this reason, when using manual mode, the user must ensure that his choice is optimum from the economic viewpoint, while My Ecodial L takes charge of checking conformity with the safety rules.

This principle is the same for all other manual choice options.

Page 3 of 25Cables


Variables used to size cables

Network characteristics:

Operational current equal to the thermal setting of the upstream protection device

Upstream short-circuit current

Upstream network impedance

Voltage

Upstream network voltage drop

Earthing arrangement

Circuit polarity

The characteristics of the relevant circuit and cable

Maximum permissible current lz equal to the current setting of the upstream protection device

Type of conductor

Type of insulation

Installation method

Ambient temperature

User coefficient

Type of protection device (circuit-breaker or fuse)


Standardised cross-sections

Cable length

Circuit layout

Duct spacing

D U max of circuit

Number of layers

Number of additional touching circuits

Output variables calculated by My Ecodial L

Theoretical number of phase conductors

Theoretical cross-section of a phase conductor

Page 4 of 25Cables


Theoretical number of neutral conductors

Theoretical cross-section of a neutral conductor

Theoretical number of earth conductors

Theoretical cross-section of an earth conductor

Cables installed in parallel

In general, it is advised to install the lowest number possible of cables in parallel. Parallel installation of a large number of cables results in poor current distribution that can lead to abnormal temperature rise.

A correction factor, called the symmetry factor, for permissible currents is contained in the standards NFC 15 - 100 - Ed 2003.

Symmetrical installation of cables as indicated below is the means to maintain the symmetry factor fs = 1.

Single-core cables

When symmetry conditions are not observed or when there are three cables per phase, the symmetry factor drops to 0.8.

Multi-core cables

Two cables per phase, with or without a neutral

Delta arrangement

/ =

Flat arrangement

/

Four cables per phase, with a neutral

Delta arrangement

Flat arrangement

Page 5 of 25Cables


Only one multi-core cable per circuit. Symmetry conditions are considered met. The symmetry factor is equal to 1.

If there is more than one multi-core cable per circuit, symmetry conditions are considered impossible and the symmetry factor drops to 0.8.

Correction factors in NFC 15-100, edition 2003

My Ecodial L is certified by UTE and therefore applies the rules in edition 2003 of standard NFC 15-100.

The following correction factors are taken into account:

f1 is the temperature correction factor (the reference T°C is 30°C for ambient conditions, 20°C for buried cables)

f2 is the grouping factor, of which there are two types: grouping of multi-core cables or circuits (table 52N in standard NFC 15-100) grouping of conduits depending on the type of environment

table 52P for conduits in air table 52Q for conduits in concrete tables 52R and 52S for buried conduits

f3 is the product of a number of factors including: the reference-method factor (table 52G), the symmetry factor (1 or 0.8), the neutral-load factor (1 or 0.84), the factor for installations where there is a risk of explosion (table BE3), the soil thermal-resistivity factor (table 52M).

Correspondence between NFC 15-100 and the UTE C 15-105 guide

Title NFC 15-100 UTE C 15-105

Insulated cables and conductors 52A BB

Determining permissible currents depending on the installation method 52C, 52G, 52H, 52J BC

Permissible currents and overload protection for the B, C, E and F reference methods in the absence of correction factors 52H BD

Permissible currents (in amperes) in buried conduits (D reference method) 52J BE

Correction factors for ambient temperatures other than 30°C 52K BF1

Page 6 of 25Cables


Help on cables

How My Ecodial L determines cable sizes

The cables are sized to satisfy a number of conditions that guarantee installation dependability. They must:

Carry the steady-state operational current and its normal transient peaks

Prevent generation of voltage drops that could interfere with the operation of certain loads, such as motors on starting, and result in costly line losses.

Correction factors for soil temperatures other than 20°C 52L BF2

Correction factors for grouping of a number of circuits or multi-core cables 52N BG1

Correction factors for installation in layers 52O BG2

Correction factors depending on the number of conduits in air and the layout 52P BH

Correction factors depending on the number of conduits in concrete and the layout 52Q BJ

Correction factors for grouping of a number of cables installed directly in soil. Single-core and multi-core cables installed horizontally or vertically 52R BK1

Correction factors for buried conduits, horizontal or vertical, with one cable or group of three single-core cables per conduit 52S BK2

Correction factors for a number of circuits or cables in a single buried conduit 52T BK3

Correction factors for buried cables, depending on the soil thermal resistivity 53M BL

K factor values for calculation of conductor thermal constraints A54 A à A54F EA

See also

Page 7 of 25Cables


Detailed calculation steps

Voltage drop

Page 8 of 25Cables


The standard stipulates a total voltage drop less than a given threshold (according to the circuit considered). My Ecodial L nevertheless lets the user distribute voltage drop on each circuit by entering a maximum voltage drop per circuit

In automatic calculation mode, My Ecodial L calculates the voltage drop on the circuit studied and compares it to the maximum voltage drop stipulated by the user. If necessary, My Ecodial L will increase cable dimensions.

My Ecodial L calculates the voltage drop on start-up and compares it to the maximum voltage drop stipulated by the standard. If necessary, My Ecodial L will increase cable size.

In manual calculation mode, My Ecodial L checks that the choices made by the user fully comply with the standard.

Protection of persons and thermal stress limitations are calclated by the short-circuit current calculation.

Short-circuit current

When a short-circuit occurs, a strong current passes through the conductors bringing them to a high temperature. The conductors and insulators must not be damaged before the protection device has time to break this current. This is the thermal stress.

My Ecodial L calculates the maximum and minimum short-circuit currents and ensures compliance with standard requirements.

For fuse protection, compliance with these requirements can lead to increased cable sizes.

The standard states that the thermal stress need not be checked when the cable is protected by a circuit-breaker and the circuit-breaker is not time-delayed.

Checking

This step is common to both calculation modes: automatic and manual.

The cross-sections and numbers of cable conductors calculated or imposed at this stage are governed by requirements concerning voltage drops and minimum short-circuit currents. If standard compliance is total in all aspects, the values are validated. Otherwise, the calculation is interrupted and the user informed of the problem.

Theoretical CSA of phase (standard NF C15-100)

This calculation is carried out in 3 steps:

1. Determination of the current Idim to be taken into account for cable sizing:

Three possibilities:

- protective-device rated current or setting,

- design current if the circuit is not protected,

- rated current of the source for the cable located between the source and the incoming protective device

Page 9 of 25Cables


2. Determination of the permissible current Iz: The permissible current is calculated using the equation below (UTE C 15-105 guide, sections B.1.2 and B.6.1)) :

where:

K3 = correction factor associated with the type of overload-protective device

Idim = current value used for conductor sizing

N = number of conductors in parallel

f = correction factor for wiring-system erection. more information

3. Calculation of the theoretical size

The theoretical size is calculated using the following equation (UTE C 15-105 guide, table A5):

where:

e and K = coefficients used in the guide

Nth = the number of parallel conductors required to obtain a CSA less than the maximum permissible value

Theoretical CSA of phase (IEC standard 60364)

This calculation is carried out in 3 steps:

1. Determination of the current Idim to be taken into account for cable sizing:

Three possibilities:

- protective-device rated current or setting,

- design current if the circuit is not protected,

- nominal current of the source for the cable located between the source and the incoming protective device

2. Determination of the permissible current Iz: The permissible current is calculated using the following equation:

where:

Page 10 of 25Cables


K3 = correction factor associated with the type of overload-protective device

Idim = current value used for conductor sizing

N = number of conductors in parallel

f = correction factor for wiring-system erection. more information

3. Calculation of the theoretical size

The theoretical size is calculated using the following equation (IEC standard 60364, part 5-52 Annex C):

where:

m and A = coefficients used in the standard

Nth = the number of parallel conductors required to obtain a CSA less than the maximum permissible value

Calculation of cable cross-section: Voltage drop requirement

The standard stipulates a total voltage drop less than a given threshold (according to the circuit considered). My Ecodial L nevertheless lets the user distribute voltage drop on each circuit by entering a maximum voltage drop per circuit

In automatic calculation mode, My Ecodial L calculates the voltage drop on the circuit studied and compares it to the maximum voltage drop stipulated by the user. If necessary, My Ecodial L will increase cable size.

My Ecodial L calculates the voltage drop on start-up and compares it to the maximum voltage drop stipulated by the standard. If necessary, My Ecodial L will increase cable size.

Warning: My Ecodial L proceeds by iteration, starting from the source. The cumulated voltage drop is the sum of the voltage drops of each stage. This means that if the cumulated voltage drop rises above the standard recommendations, My Ecodial L will only increase cable cross-section of the last stage and will not modify the cables of the previous stages, which is not always the best solution. In this case, you should change to manual mode and increase the cross-section of the upstream cable.

Calculation of the voltage drop over the circuit

Page 11 of 25Cables


Glossary of variables:

Calculation of voltage drop on motor start-up

dU Voltage drop over the circuit.

dUCumule Cumulated voltage drop of the upstream circuit.

Nph Number of phase conductors.

Sph Cross-section of a phase conductor.

R Phase linear resistance, taken from tables according to metal type, insulation type and conductor cross-section.

Phase linear reactance, taken the tables according to the number of touching cables.

L Cable length.

IB Nominal current.

Uo Voltage.

k Coefficient depending on polarity, taken from tables.

cos Cosine phi.

sin Sine phi.

dUAmont Upstream circuit voltage drop (Value updated at end of calculation.

Page 12 of 25Cables



Sizing for thermal stress

Calculation of minimum short-circuit currents

When a short-circuit occurs, a strong current passes through the conductors bringing them to a high temperature. The conductors and insulation must not be damaged before the protection device has time to break this current. This is the thermal stress limit.

My Ecodial L calculates the minimum short-circuit currents and ensures that the requirements of the standards are complied with.


For a phase to earth fault, a touch voltage is created on the exposed conductive parts of the equipment. Protection of people against indirect contact defined in the standard stipulates that the faulty circuit must be broken within a time depending on this touch voltage.



R Phase resistance, according to metal type, insulation type and conductor cross-section.

X Phase reactance, according to number of touching cables.

L Cable length.

Idem Inrush current on start-up.

Uo Voltage.

k

Coefficient depending on polarity:

Polarity Coefficient

3P + N 1

2P

1Ph 2

cosdem phi Cos phi on start-up.

sindem phi Sin phi on start-up.

dUDemAmont Voltage drop on start-up of the upstream circuit.

Page 13 of 25Cables


For a TN arrangement, we check that Ph/Earth min lsc is greater than the circuit-breaker magnetic threshold. Compliance with this requirement may lead to increased cable sizes or to the installation of a residual current relay.

For a TT arrangement, a residual current device is placed at the head of the installation.

For an IT arrangement, on the first phase to earth fault, the fault current is not dangerous and does not trip the protection device (tripping only occurs on the second fault). On the second fault, the short-circuit is phase to phase. Thus the phase to earth fault short-circuit current is not used for cable sizing.

Phase to Phase minimum short-circuit current Phase to Neutral minimum short-circuit current Phase to Earth minimum short-circuit current

Calculation of Phase to Phase min lsc

Consideration of the Phase to Phase min lsc current




The standard states that the thermal stress need not be checked when the cable is protected by a circuit-breaker.

Calculation of Phase to Phase min lsc:


Icc min Minimum short-circuit current.

Rphamont Upstream phase resistance.

Page 14 of 25Cables


Calculation of Phase to Neutral min lsc

Consideration of the Phase to Neutral min lsc current




The standard states that the thermal stress need not be checked when the cable is protected by a circuit-breaker.

Calculation of Phase to Neutral min lsc:

Xphamont

Upstream phase reactance.

The choice between the normal variable set and the replacement variable set is made as follows:

If the circuit is a normal circuit, the Normal source values are used.

If the circuit is a replacement circuit, the Replacement source values are used.

If the circuit is supplied by a Normal and Replacement source, the values with the greatest

impedance are taken:

Roph Phase resistance (depends on metal, insulation and conductor cross-section)

X Phase reactance (depends on number of touching cables)



L Cable length.

Uo Voltage.

CMIN Constant set for min lsc.

Page 15 of 25Cables



Calculation of Phase to Earth min lsc

Consideration of the Phase to Earth min lsc current

When a short-circuit occurs, a strong current passes through the conductors bringing them to a high

Icc min Minimum short-circuit current.

Rneamont Upstream neutral resistance.

Xneamont

Upstream phase reactance.

The choice between the normal variable set and the replacement variable set is made as follows:

If the circuit is a normal circuit, the Normal source values are used.

If the circuit is a replacement circuit, the Replacement source values are used.

If the circuit is supplied by a Normal and Replacement source, the values with the greatest

impedance are taken:

Rone Neutral linear resistance taken from the tables depending on metal type, insulation type and conductor cross-section.

Roph Phase linear resistance taken from the tables depending on metal type, insulation type and conductor cross-section.

X Phase linear reactance taken from the tables depending on number of touching cables.


Sne Cross-section of a neutral conductor.


Nne Number of neutral conductors.

L Cable length.

Uo Voltage.

CMIN Constant set for min lsc.

Page 16 of 25Cables


temperature. The conductors and insulation must not be damaged before the protection device has time to break this current. This is the thermal stress limit.



For a phase to earth fault, a touch voltage is created on the exposed conductive parts of the equipment. Protection of people against indirect contacts defined in the standard stipulates that the faulty circuit must be broken within a time depending on this touch voltage.

In the TN arrangement, we check that Ph/Earth min lsc is greater than the circuit-breaker magnetic threshold. Compliance with this requirement may lead to increased cable sizes or to the installation of a residual current relay.

In the TT arrangement, a residual current device is placed at the head of the installation.


Icc min Minimum short-circuit current

Rpeamont Upstream earth resistance.

Xpeamont

Upstream earth reactance. To calculate this reactance:

Type of source Values used

Normal Values derived from the Normal source

Replacement Values derived from the Replacement source

Normal / Replacement Values with the greatest impedance

Rope Earth linear resistance taken from the tables depending on metal type, insulation type and conductor cross-section.

Roph Phase linear resistance taken from the tables depending on metal type, insulation type and conductor cross-section.

Page 17 of 25Cables


Calculation of maximum short-circuit currents

The maximum short-circuit currents are used to ensure that circuit-breaker breaking capacity is properly sized.

Three-phase maximum short-circuit current Two-phase maximum short-circuit current Single-phase maximum short-circuit current

Calculation of single-phase max lsc RboN = RphAmont + RneAmont + RphLiais + RneLias

XbN = XphAmont + XneAmont + XphLiais + XneLiais


X Phase linear reactance taken from the tables depending on number of touching cables.


Spe Cross-section of a neutral conductor.


Npe Number of neutral conductors.

Alpha

Coefficient depending on earthing arrangement:

Earthing arrangement Alpha

IT with neutral 0.5

IT without neutral

TT, TN-C and TN-S 1

L Cable length.

Uo Voltage.

CMIN Constant fixed for min lsc.

Page 18 of 25Cables


Calculation of two-phase max lsc RboPhPh = 2xRphAmont + 2xRphLiais

XbPhPh = 2xXphAmont + 2xXphLiais

RneAmont Upstream circuit neutral resistance.

XneAmont Upstream circuit neutral reactance.

RphLiais Connection phase resistance:

RhoPh Phase resistance, depending on metal type, insulation type and conductor cross-section.

XphLiais Connection phase reactance:

RneLiais

Connection neutral resistance:

RhoNe Neutral resistance, depending on metal type, insulation type and conductor cross-section.

XneLiais

Connection neutral reactance:

X Phase reactance, depending on number of touching cables.



Nne Number of neutral conductors.

Sne Cross-section of a neutral conductor.

L Cable length.

Uo Voltage.

CMAX Constant fixed for max lsc.

Page 19 of 25Cables



Calculation of three-phase max lsc RboPh = RphAmont + RphLiais

XbPh = XphAmont + XphLiais


RphAmont Upstream circuit phase resistance.

XphAmont Upstream circuit phase reactance.



XphLiais

Connection phase reactance:



X Phase linear reactance, depending on number of touching cables.

L Cable length.

Uo Voltage.


RphAmont Upstream circuit phase resistance.

XphAmont Upstream circuit phase reactance.


Page 20 of 25Cables


Calculation of total coefficient k (standard NF C 15-100)

This coefficient k results from the influences of the installation method, circuit grouping and ambient temperature. It is used to determine the fictitious current Iz’ that can flow in the conductor without danger ( Iz’ = Iz/k, where Iz is the permissible current of the conductor).

Calculation of total coefficient k: k = (ktemp x kdiv x Kame x kcouche x Kgroupe x Ksymétrie x Krthsol x kutil) / kprot

where:


XphLiais Connection phase reactance:



X Phase reactance, depending on number of touching cables.

L Cable length.

Uo Voltage.


ktemp correction factor depending on temperature

kdiv correction factor depending on installation method

kame correction factor depending on neutral load

kcouche correction factor depending on number of layers

kgroupe correction factor depending on grouping of several cables

Ksymétrie Symmetry coefficient

krthsol correction factor depending on the thermal resisitivity of the ground

kutil user-defined coefficient

kprot coefficient depending on protection

Page 21 of 25Cables


ktemp

where:

kdiv

Value taken from table 52-G of the standard.

Kame

For 3-phase applications, if the neutral conductor carries a current without any corresponding reduction in the load on the phase conductors, the neutral must be taken into account when determining the number of live conductors. Such currents may be due, for example, to the presence of high harmonic currents in 3-phase circuits. In this case, a coefficient equal to 0.84 is applied (§524.2.4).

kcouche

Value taken from tables 52N, 52O, 52R, 52S, 52T of the standard.

kgroupe

based on the installation method, the arrangement of the cirucits and the spacing of the conduits, My Ecodial L looks in the appropriate tables (52N, 52O, 52P, 52Q, 52R, 52S, 52T) of the standard for the reduction to be applied.

Ksymétrie

for an odd number of conductors (greater than 1), this coefficient is equal to 0.8. Otherwise it is 1 (§523.6).

krthsol

Tisolant maximum operating temperature for insulation: table 52F or 52L (70° if PVC, 90° if PRC)

Tambiante ambient temperature

Treference reference temperature as per installation method: chapter 523.2 (20° for buried cables, 30° for cables in air)

Page 22 of 25Cables


Value taken from table 52M

kutil

This coefficient is used to take a special factor known by the user (e.g. explosion hazard, etc.) into account in the cable cross-section calculation.

kprot

The 1999 version of standard NFC15-100 introduced a protection coefficient k3 specifically for gG fuses.

The coefficient depends on the rated current :

The 2003 version of standard NFC15 -100 modified the values of this coefficient :

Calculation of total coefficient k (IEC standard)

This coefficient k results from the influences of the installation method, circuit grouping and ambient temperature. It is used to determine the fictitious current Iz’ that can flow through the conductor without danger ( Iz’ = Iz/k, where Iz is the permissible current of the conductor).

Calculation of total coefficient k k = (ktemp x kame x kjointif x kutil x krthsol) / kprot

where:

In<= 10A k3=1.31

10A <= In <= 25A k3=1.21

In >= 25A k3=1.1

In<= 16A k3=1.31

In >= 16A k3=1.1

ktemp correction factor depending on temperature

krthsol correction factor depending on the thermal resisitivity of the ground

kame correction factor depending on circuit core

Page 23 of 25Cables


ktemp

For cables in air, My Ecodial L applies the correction factor of table 52-D1 from the IEC364-5-523 depending on the material and ambient temperature.

For buried cables, My Ecodial L applies the correction factor of table 52-D2 from the IEC364-5-523 depending on the material and ambient temperature.

krthsol

Value taken from table A.52-16

kame

For 3-phase applications, if the neutral conductor carries a current without any corresponding reduction in the load on the phase conductors, the neutral must be taken into account when determining the number of live conductors. Such currents may be due, for example, to the presence of high harmonic currents in 3-phase circuits. In this case, a coefficient equal to 0.84 is applied (table D.52-1).

kjointif

For groups of more than one circuit or more than one multi-core cable, My Ecodial L applies the correction factors of table 52-E1.

For groups of more than one circuit with cables laid directly in the ground, My Ecodial L applies the correction factors of table 52-E2.

For groups of more than one circuit with cables laid in ducts in the ground, My Ecodial L applies the correction factors of table 52-E3.

For groups of more than one circuit with other installation methods, My Ecodial L applies the correction factors of table 52-E4 and table 52-E5.

kutil

This coefficient is used to take a special factor known by the user (e.g. explosion hazard, etc.) into account in the cable cross-section calculation.

kjointif correction factor depending on number of touching cables

kutil user-defined coefficient

kprot coefficient depending on protection

Page 24 of 25Cables


kprot

This coefficient assumes the value of 1.21 for circuits protected by a fuse (otherwise it is equal to 1).

Page 25 of 25Cables


Circuit-breakers

Input parameters

Limitations My Ecodial L does not take temperature into account in calculations nor does it consider derating problems when circuit breakers are exposed to temperatures greater than their reference temperature. Therefore, My Ecodial L does not apply any temperature derating that may be required due to the mounting of a number of circuit breakers in a switchboard.

General The circuit-breaker performs all the basic functions required in an electrical installation, namely:

disconnection

control

current interruption and emergency power off (possible via a release for remote tripping)

isolation for mechanical servicing

protection against: overloads short-circuits insulation faults (depending on the earthing arrangement, a residual-current relay may be necessary) voltage drops (via an undervoltage release)

remote control (via motor mechanism or electrically operated circuit breaker)

measurement / indication (normally an option with electronic control units)

This property makes it the basic device for all electrical distribution.

Fundamental characteristics of a circuit-breaker Circuit-breaker limiting capacity Choosing a circuit-breaker

Co-ordination between circuit-breakers Cascading Discrimination

Circuit-breaker parameters

Description Content

Range Circuit-breaker range: Multi 9 - Compact - Masterpact

Trip unit / curve Circuit-breaker protection curve or trip unit type

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No. of poles protected

Number of poles interrupted (xP) and protected (xd)

4P4d 4 poles interrupted and protected

4P3d+OSN 4 poles interrupted and 3 poles protected plus oversized neutral protection (option Over Sized Neutral)

4P3d+Nr 4 poles interrupted and 3 poles protected plus half neutral protection



1P1d 1 pole interrupted and protected

Fire protection

Fire protection Yes - No If yes, residual current protection will have a threshold < 500 mA and a time delay of 50ms or 90 ms This parameter is not displayed if the load is a power socket.

Addit. prot. against direct contacts

This parameter is displayed only if the load is a power socket. It is used to take into account section 411.3.3 of installation standards IEC 60364 and NF C 15-100

Residual current protection YES

Integration with the protection device

Selection of type of RCD integration.

- module integrated in the protection device, i.e. in the circuit breaker or trip unit.

- add-on module (separate)

Class

Two Classes are available: A and AC, that can be associated with two types:

si : super immunised

siE : special external influence

Designation of the residual current device Designation of the chosen RCD

Sensitivity Tripping threshold on earth leakage current

Time delay interval RCD time delay setting

Thermal setting l (A) Setting of the thermal protection (according to the load to be protected)

Magnetic setting l (A) Setting of the magnetic protection

Nominal rating Value of the maximum rating of the type of circuit-breaker chosen. Commonly referred to as the frame size.

Rating Rating of protection device

Im setting Value of the setting on the front panel of the magnetic protection

Ir setting Value of the setting on the front panel of the thermal protection

I0 setting Value of the setting on the front panel of the thermal protection

Remote control Choice of remote control– Without - With

Cascading requested Choice of equipment using the cascading technique YES - NO



See Magnetic setting in My Ecodial L

Electrical protection

Where:

The fundamental characteristics of a circuit-breaker

Rated operational current Ue:

The voltage(s) at which the device can be used.

Rated current In:

Discrimination requested Determination of the discrimination limitYES - NO

Installation Type of installation Fixed – Draw-out

Time delay interval Trip unit time delay setting

Ib operational current of loads

Iz permissible current in the conductor

In nominal current or current setting of the protection device

I2 conventional operating current of the protection device

Isc 3Ph maximum short-circuit current (Ik3max)



The maximum value of the uninterrupted current that can be withstood by a circuit-breaker equipped with a trip unit at an ambient temperature specified by the manufacturer, complying with the specified temperature rise limits. For example, a NS160N equipped with a TM-D125 trip unit has a rated current ln of 125 A.

Circuit-breaker frame size:

When a circuit-breaker can be equipped with several trip units of different rated currents, the frame size corresponds to the highest rated current of the trip units with which it may be equipped. For example, a NS250N can accommodate the trip units TM-D32 (In = 32 A), TM-D160 (In = 160 A), TM-D200 (In = 200 A). The frame size is 250 A.

Current setting (Irth or Ir) of overload releases:

Except for Multi 9 circuit-breakers that are easily interchangeable, industrial circuit-breakers are equipped with removable trip units. Moreover, to adapt the circuit-breaker to circuit characteristics and avoid oversizing the cables, the trip units are in turn normally adjustable.

The current setting lr (or lrth) is the current used to determine the protection conditions provided by the circuit-breaker. It also represents the maximum current that the circuit-breaker can withstand without tripping.

This value must be greater than the operational current lb and less than the permissible current in the conductors lz.

Thermal releases are normally adjustable from 0.7 to 1 x ln, whereas electronic releases generally offer a wider range (commonly from 0.4 to 1 x In).

Operating current (Im) of short-circuit releases

The role of a short-circuit release (magnetic or short time) is to ensure fast opening of the circuit-breaker for high overcurrents.

Breaking capacity (Icu or Icn)

The breaking capacity is the highest short-circuit current (prospective current) that a circuit-breaker can break at a given voltage. It is normally expressed in symmetrical kA RMS and is referred to by lcu (ultimate breaking capacity for industrial circuit-breakers) and lcn (rated breaking capacity) for domestic or similar circuit-breakers .

Circuit-breaker polarity

The number of poles interrupted during tripping and the number of poles monitored by a thermal relay. For example, if circuit-breaker polarity is 4P3D, 4 poles will be interrputed when the circuit-breaker is tripped, but only 3 are equipped with a thermal relay, thus the neutral is not monitored. Consult the selection table for neutral conductor protection on page H1-37 of the “Electrical Installation Guide”.

Limitation

Circuit-breaker limiting capacity The limiting capacity of a circuit-breaker expresses the extent to which it can let only a current lower than the prospective fault current through on a short-circuit. This characteristic is supplied by the manufacturer through the limitation curves, representing the limited peak lsc short-circuit current and the limited thermal stress according to the prospective RMS short-circuit current.



This forms the basis of the cascading technique.

For more details, see page 13 of the" Low Voltage Expert Guide" no. 5

Advantages of limitation Implementation of limiting circuit-breakers offers many advantages:

Enhanced network protection: limiting circuit-breakers greatly attenuate all the harmful effects of short-circuit currents on an installation.

Reduction of thermal effects: less temperature rise in the conductors, thus increased service life for cables.

Reduction of mechanical effects: reduced electrodynamic repulsion forces, thus less risk of deformation or breakage, particularly for the electrical contacts.

Reduction of electromagnetic effects: less disturbance to the measurement instruments placed near an electric circuit

These circuit-breakers thus help enhance the protection of cables, busbar trunking systems and electrical switchgear, thereby slowing down installation ageing.



Choosing a circuit-breaker

A circuit-breaker is chosen according to:

The electrical characteristics of the installation on which it is installed.

The environment in which it is found, ambient temperature, installation inside an enclosure, climatic conditions.

Operating requirements: discrimination, possible need of auxiliary functions such as remote control, rotary handle, auxiliary contacts, MN or MX releases, insertion in a local or supervisory communication network, etc.

Installation rules, in particular for the protection of persons.

Characteristics of the loads, such as motors, fluorescent lighting, LV/LV transformer, etc.

Choosing a circuit-breaker according to breaking capacity Installation of a circuit-breaker in LV distribution must satisfy one of the two conditions below, as per the specifications of standard NF C 15-100:

Either it must have a breaking capacity at least equal to the prospective short-circuit current at its installation point

Or, if this is not the case, it must be associated with another breaking device placed upstream having the necessary breaking capacity. In the latter case, the characteristics of both devices must be coordinated so that the energy flowing through the device placed upstream is not greater than the energy that the downstream device and the busbar trunking protected by these devices can withstand without damage. This possibility is advantageously used in fuse/circuit-breaker and circuit-breaker/circuit-breaker combinations known as cascading, which uses the high limiting capacity of circuit-breakers.

My Ecodial L selects the most suitable circuit-breaker on the basis of a number of parameters covering the characteristics defined in the first paragraph. This choice complies with the specifications of standard NF C 15-100.

How My Ecodial L chooses In automatic calculation mode, My Ecodial L takes into account the equipment to be protected by the circuit-breaker. Circuit-breakers protecting a motor and those protecting an LV/LV transformer are treated differently by My Ecodial L, due to the specific features of these two components.

My Ecodial L then considers cascading. If cascading is not requested, My Ecodial L makes its choice according to many parameters, such as rated current, voltage, discrimination request, circuit-breaker polarity, i.e. the number of poles interrupted and the number of poles protected, the application (the equipment located downstream of the circuit-breaker), the chosen standard and the protection type. This choice is based on tables supplied by the manufacturer that give the most suitable circuit-breaker for each configuration.

If cascading is requested, then the choice is made with the addition of two new parameters: the upstream and downstream circuit-breakers, if they exist. My Ecodial L uses the cascading tables given by the manufacturer to make its choice. These tables are found in the catalogues.

Once it has chosen the circuit-breaker, My Ecodial L selects a suitable trip unit, then determines the thermal current setting of the circuit-breaker according to the rated current of the circuit, followed by the magnetic protection current of the circuit-breaker taking into account the values of the various short-circuit currents and cable cross-sections.

In manual calculation mode, My Ecodial L checks that the user’s choices are both satisfactory and in compliance with the standard. The differences for motor circuit-breakers or circuit-breakers protecting an LV/LV transformer and for cascading apply as for automatic calculation mode. If it is not possible to find a circuit-breaker satisfying both the user’s choices and the



standard, My Ecodial L displays a warning message. In manual mode, My Ecodial L does not automatically modify the user’s choices.

thermal-magnetic circuit-breaker electronic circuit-breaker

Cascading

Definition of cascading Cascading uses the limiting capacity of a circuit-breaker to allow installation of a downstream circuit-breaker of lower performance. The upstream circuit-breaker acts as a barrier for high short-circuit currents, allowing the use of a downstream circuit-breaker with a breaking capacity that is far lower than the prospective short-circuit current.

Implementation conditions Standard NF C 15-100 allows this type of association provided that the energy flowing through the upstream circuit-breaker is not greater than the energy that can be withstood without damage by the downstream circuit-breaker(s) benefiting from the cascading capacity of the upstream circuit-breaker.

The cascading possibilities are checked by laboratory tests, then supplied by the manufacturer.

Advantage of cascading As the current is limited all along the circuits controlled by the limiting circuit-breaker, cascading concerns all the installed placed downstream of this circuit-breaker.

It is thus not limited to two consecutive devices and can be applied even between circuit-breakers located in different switchboards. The result is that installation of a single limiting circuit-breaker can lead to simplifications and major savings for the entire downstream installation:

Simplification of downstream short-circuit current calculations, as these currents are extremely limited

Simplification of choice of device

Savings on these devices as short-circuit current limitation allows use of devices with lower performance and therefore lower in cost.

Savings on enclosures as the devices with lower performance are generally smaller.

If you have chosen cascading in the general circuit characteristics, My Ecodial L will use cascading to reduce the size of the downstream circuit-breakers as per standard NF C 15-100 and based on manufacturer data.

For more details on cascading, see page 17 of the "Low Voltage Expert Guide" no. 5.

Discrimination

See also



Principle According to § 1.4 of standard IEC 60947-2:

Discrimination consists of ensuring co-ordination between the operating characteristics of serial-connected circuit-breakers so that if a fault occurs downstream, only the circuit-breaker placed immediately upstream of the fault trips.

Total or partial discrimination Discrimination between two circuit-breakers A and B is total if B operates alone for all short-circuit values up to the three-phase solid short-circuit current lscB at the point at which it is placed.

Discrimination is partial if B operates alone only up to a prospective short-circuit current lc less than lscB. Beyond this value, A and B operate simultaneously.

Discrimination techniques

Current discrimination

This type of discrimination is based on the current shift between the protection curves. It is total if the short-circuit current lscB downstream of B is less than the magnetic tripping threshold lrmA. Otherwise it is partial.

Current discrimination is particularly used when the ratings of the upstream and downstream circuit-breakers are different. Implemented with fast-acting circuit-breakers, it is often partial and its level is only IrmA.

Time discrimination

This type of discrimination is based on the time shift of the tripping curves and is determined graphically. It requires the addition



of time delay units in the circuit-breaker tripping systems and circuit-breakers that are able to withstand the thermal and electrodynamic effects of the current during the delay time.

If you have chosen discrimination in the general circuit characteristics, My Ecodial L will choose and set the various circuit-breakers in the circuit to obtain discrimination.

CAUTION: use of circuit-breakers with delayed tripping means that My Ecodial L must check the thermal requirement, in other words that the cable downstream of the delayed circuit-breaker can withstand the energy flowing through it during this short delay.

For more details on discrimination, see page 19 of the "Low Voltage Expert Guide" no. 5.

Magnetic setting

When checking the protection function against direct and indirect contacts, My Ecodial L can automatically reduce the magnetic setting to a value under the applicable fault current, depending on the earthing arrangement.

If that is not sufficient or if the magnetic setting is not adjustable, My Ecodial L increases the size of the conductors. In the calculation results, an optimisation message requests that the magnetic setting be reduced or an RCD be installed.

Is it possible to reduce the magnetic setting manually?

Compact range



It is possible to manually adjust the magnetic setting by modifying the corresponding field in the step-by-step calculation window accessed via the Calculation menu (or F5). Caution, manual modifications of settings are not possible for certain trip units.

Multi 9 range

It is not possible to manually adjust the magnetic setting. This modular range of circuit breakers offers different tripping curves identified by letters. The C curve is the most common and corresponds to a magnetic setting from 5-7 to 10 In.

My Ecodial L also includes a display module for tripping curves (More information).

Input parameters

See also



Switch

The switch is chosen in coordination with the circuit-breaker.

Description Content

Residual current protection Presence of a residual current device

No. of poles Number of poles interrupted

Switch Switch reference

Page 1 of 1Switch


Fuse-combination units

Parameters

General

General presentation

My Ecodial L proposes two types of protection under the fuse-combination unit heading: true fuse-combination units and fuses alone. The choice is made using the Range input parameter.

As for circuit breakers, earth-leakage protection can be associated with these devices. However, given that fuse-combination units cannot be controlled, an AC4 (or AC1 if associated with a motor) type contactor is also proposed.

fuse-combination units

A fuse-combination unit is a protection device made up of two parts:

a fuse, representing the actual protection device. It is characterised by:

its rating

its breaking capacity

its form, which is in turn defined by a type (or standard) and size

a fuse carrier characterised by:

its type: disconnector or switch-disconnector

its rating

number of poles

fuse alone

My Ecodial L maintains the possibility of choosing a fuse without a fuse carrier, as was the case in My Ecodial L versions prior to version 3.4. In this case the fuse is characterised by:

its rating

its breaking capacity

However, its form is not taken into account.

Fuse-combination unit choices

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Fuse combination-unit parameters

Fuse-combination units without earth-leakage protection Fuse-combination units with earth-leakage protection

Fuse-combination units without earth-leakage protection

Description Content

Range Fuse-combination unit range or fuse model if a fuse alone is selected.

Available fuse-combination unit ranges: Multi 9, Fupact, GK1, GS1, LS1, Diazed Available fuse models: aM, gG, gM

FCU typeContains the fuse-combination unit type. Two possible choices: disconnector or switch-disconnector. If the Diazed range is chosen or a fuse alone, this field contains: -

Fuse type (standard)

For ranges other than Diazed, there are 3 possible choices: DIN(NH), NFC, BS If the Diazed range is chosen, there is only one possible choice: Diazed If the range chosen is a fuse alone, this field contains: -


No. of poles interrupted (xP) and protected (xf)

4P4f = 4 poles interrupted and protected



1P1f = 1 pole interrupted and protected

FCU designation This field is empty if the Diazed range or a fuse alone is chosen

FCU rating (A) This field is not visible if the Diazed range or a fuse alone is chosen

Fuse model Model of fuses used by the fuse-combination unit. Four choices are possible: gG, aM, gM, Diazed

Fuse rating (A) Rating of fuses protecting the phases

Rating of neutral fuse (A)

Rating of the fuse protecting the neutral. This field is not visible if the value is greater than that of the fuses protecting the phases. This is the case when the third-order harmonics (included in the THDI characteristic associated with the cable component) is greater than 33%.

Fuse size

The available values depend on the fuse type (standard): DIN (NH): NH0, NH00, NH000, NH1 to NH4 NFC: 8.5x31.5, 10x38, 14x51, 22x58 BS: A1 to A4, B1 to B4, C1 to C3, D1, F1 Diazed: DI, DII, DIII, DIV For fuses alone, this field contains the fuse model.



Fuse-combination units with earth-leakage protection In addition to the above parameters, the following parameters are displayed.

Fuse-combination unit choices

Earth leakage protection: No

Contactor designation

If the neutral is protected by a fuse (number of poles protected = 4P4f), the installation standard (§431.3) indicates that it cannot be interrupted before the phases. Given that fuse-combination units cannot be controlled, My Ecodial L proposes a type AC1 contactor.

Contactor rating Rating of type AC1 contactor.

Discrimination requested Selection of devices implementing discrimination YES - NO

Description Content

Earth leakage protection: YES

Integration with the protective device

Only a separate residual current device (RCD) can be associated with a fuse-combination unit. Therefore only one choice is possible: Separate

Class

Two available classes: A and AC which can be associated with two types:

si : super immunised

siE : special for external influence

Earth-leakage protection designation Designation of selected RCD

Sensitivity Earth leakage tripping threshold

Time delay setting Time-delay setting for the RCD

Contactor designationGiven that fuse-combination units cannot be controlled, My Ecodial L associates a type AC1 contactor with the RCD. If the protected circuit is a motor circuit, the associated contactor (type AC4) is used.

Contactor rating Rating of type AC1 contactor. This characteristic is not displayed if the contactor is type AC4 (motor control)



My Ecodial L choice method

Automatic mode

In automatic calculation mode, My Ecodial L looks at the type of circuit to be protected. Fuse-combination units protecting a motor are treated differently by My Ecodial L.

General case

To choose a fuse-combination unit, My Ecodial L takes into account two types of parameters:

1. Electrical parameters

Circuit voltage

Rated current and possibly the current flowing in the neutral (if the third-order harmonics exceed 33%)

The maximum short-circuit current at the point of connection

The type of network (single-phase or three-phase, with or without neutral)

2. User defined parameters

Range

FCU type

Fuse type (standard)

Fuse model

Fuse size


If no solution is available, My Ecodial L expands its search, no longer taking into account the user-defined parameters except for the Range and the Number of poles protected.

Motor protection

The search is carried out in two phases:

1. Search for the fuse that can be associated with the motor. It is based on two characteristics:

Model

Rating

2. Search for the fuse-combination unit capable of housing the fuse and satisfying the conditions indicated in the general case.



Manual mode

In manual calculation mode, My Ecodial L checks that the user's choice is compatible with the characteristics of the network and the standard. If the choice is refused, an alert is displayed. In manual mode, My Ecodial L does not automatically modify the user's choices.



Protection - Conductor

Definition of any load in final distribution

Remarks Circuit polarity is determined by the load:

3P+N Three-phase network with distributed neutral

Imposed in TN-C (PE and N combined)

3P Three-phase network with undistributed neutral

2P Two-phase network

1P Single-phase network

Protection, sizing of conductors, etc. depends on this polarity.

As circuit power and current (lb) are interdependent, the user must only enter one of them. My Ecodial L will then calculate the other value according to the circuit polarity and power factor.

Earthing arrangement: allows change from TN-C to TN-S.

Protection - Conductor – Conductor

Definition of any load in final distribution.

Description Content

Length (m) - C1 Length of cable in metres

No. of identical circuits Number of identical circuits

Ib (A) Circuit nominal current

Circuit polarity Circuit polarity 3P+N – 3P – 2P – 1P - Upstream (= upstream circuit polarity)

Earthing arrangement TT - IT - TN-C - TN-S - Upstream (= upstream earthing arrangement)

Power (kW) Nominal circuit power

Power factor Circuit cos

Description Content

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Protection, sizing of conductors, etc. depends on this polarity.



Coupler

Length (m) – C7 Length of cable in metres

Length (m) – D7 Length of busbar trunking in metres



Circuit polarity Circuit polarity 3P+N – 3P – 2P – 1P - Upstream (= upstream circuit polarity)

Earthing arrangement TT - IT - TN-C - TN-S - Upstream (= upstream earthing arrangement)



Description Content



Downstream circuit polarity Circuit polarity: 3P+N – 3P – 2P – 1P - Upstream (= polarity of the upstream circuit)

Earthing arrangement TT - IT - TN-C - TN-S - Upstream (= upstream earthing system)



Remarks Circuit polarity is fixed by the load:


Value imposed in TN-C (PE and N combined)




Protection, sizing of conductors, etc. depend on this polarity.

Circuit power and current (lb) are interdependent: the user must only enter one of them. My Ecodial L will calculate the other value according to circuit polarity and cos phi.


CAUTION - The coupler component must not be used for any purposes other than coupling. - The coupler component cannot be placed on the diagram like a cable or load protection device.

Power (kW) Circuit nominal power

Power factor Circuit cos phi value



Loads

This component is used to represent loads other than motors (with or without variable speed drives), power sockets and lighting. Once certain load characteristics have been entered, My Ecodial L can simulate the load during the calculation.

Definition of any load in final distribution.






Description Content

Length (m) Length of cable in metres


Ib (A) Nominal circuit current

Circuit polarity Circuit polarity 3P+N – 3P – 2P – 1P - Upstream ( = upstream circuit polarity)

Earthing arrangement TT - IT - TN-C - TN-S - Upstream ( = upstream earthing arrangement)



Type of load My Ecodial L offers you a variety of choices: standard, corresponding to the general case, or certain special cases: heating floor – Instrumentation/measurement – Public lighting – luminous signs – Loads that do not require residual current protection.

Environment Various choices are proposed.

Ph/Earth fault max break time Maximum interruption time of a phase to earth fault: 5s - <5s

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Protection, sizing of conductors, etc. depends on this polarity


Earthing arrangement: some earthing arrangement changes are possible, such as the change from TN-C to TN-S.

Special loads (heating floor, etc.) refer to special standards. My Ecodial L ensures compliance with these special standards.

The various types of environment (housing premises, etc.) also lead to application of special standards, used by My Ecodial L for calculations if applicable.

The socket component

This component allows power socket distribution in an LV electrical installation.

Operation In an installation block diagram, it is important not to describe the installation in excessive detail as this could complicate the representation.

The socket macro-component consists of a protection device, a cable and one or more power sockets. The user does not enter the number of sockets.

My Ecodial L considers that the power sockets are parallel-connected. The user must thus enter the sum of the currents for all the sockets.

Input parameters

Description Content


Ib (A) Sum of the currents drawn by all the devices connected to the power sockets

Downstream circuit polarity Circuit polarity 3P+N – 3P – 2P – 1P - Upstream ( = upstream circuit polarity)

Page 2 of 3Loads


Earthing arrangement TT - IT - TN-C - TN-S - Upstream ( = upstream earthing system)

Power (kW) Nominal circuit power. This is not input data

Power factor Circuit cosine phi

Load type My Ecodial L offers a variety of choices: Others, corresponding to general cases, and certain special cases: Instrumentation/measurement –– Computing and Office Automation

Environment A variety of choices are proposed: Others, corresponding to general cases, and certain special cases.

Page 3 of 3Loads


Lighting

Input parameters

Normal incandescent or halogen lamps The power drawn by these lamps is equal to the nominal power indicated by the manufacturer. The corresponding currents drawn are:

for three-phase and

for single-phase applications.

For a lamp, the presence of halogen gas ensures a more concentrated source. Efficiency is greater and service life is doubled.

When energised, the cold filament causes short but high current peaks.

Conventional fluorescent and HF tubes To operate, a fluorescent tube needs a ballast and an ignition device (or starter):

The ballast, which is a reactor, is necessary to limit the preheating current, produce the ignition voltage and stabilise the current. The presence of the ballast gives these lighting circuits a low power factor (around 0.6). If left uncorrected, this would result in a high consumption of reactive energy, overloading the network and often penalties billed by the utility. For this reason, fluorescent tubes are mounted with an individual universal capacitor and are said to be corrected. My Ecodial L only considers the case of corrected tubes.

The purpose of the ignition device (starter) is to generate an overvoltage used to switch on the tube.

Fluorescent tubes with HF ballast offer a number of advantages over conventional tubes: energy savings of around 25%, rapid, direct ignition, no stroboscopic or flicker effect.

The power Pn (W) indicated on a fluorescent tube does not include the power drawn by the ballast.

Total starting current in A

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My Ecodial L proposes standard ballast power values according to the type of lamp (some types do not need ballast, in which case My Ecodial L sets the ballast value to zero) and its power. My Ecodial L also proposes a standard power factor. It is possible to change these values by clicking on the relevant box.

Disturbances

The ballast, the capacitor and the actual operation of the tube generate disturbances on switch-on:

For conventional fluorescent tubes, there is a moderate overload when the operating current is established (1.1 to 1.5 ln according to starter type for 1 s)

Tubes with electronic ballast may generate a current peak when switched on for the first time, as well as 30 kHz earth leakage currents due to the electronic components.

Furthermore, under steady state conditions, harmonic currents are present (sinusoidal currents with frequencies equal to whole-number multiples of 50 Hz). The total harmonic current may reach 70 to 80% of the nominal load current of the phases. It is therefore important to provide a neutral cross-section equal to the phase cross-section, which is exactly what My Ecodial L does.

Discharge lamps These are:

High pressure sodium vapour lamps

Low pressure sodium vapour lamps

Metal iodide lamps (mercury vapour + metal halide)

High-pressure fluorescent lamps (mercury vapour + fluorescent substance)

These lamps use the principle of electrical discharge in an impervious enclosure filled with gas or vapour from a metal component, at a specific pressure.

Moreover, these lamps have long ignition times during which they consume a current la greater than their nominal current ln. My Ecodial L provides the power, nominal current and start-up current for the various types of lamps.

Lighting distribution by BTSs

Lighting input parameters

See also

Description Content

Length (m) – C1 Length in metres of cable

Page 2 of 3Lighting


When the "Light source" input field us double-clicked and a light source is selected along with its power, My Ecodial L proposes typical values for the power factor and ballast power. These values can be modified manually if required.

Special case for lighting fixtures (luminaires) connected to a strip lighting type BTS:

The strip lighting application is used only with the Protection - Conductor - Conductor - Lighting circuit, in which the first conductor is a cable and the second a BTS. In this case, the following constraints apply to the lighting:

only one type of luminaire is authorised: 58 W fluorescent tube with compensated inductive ballast

number of lamps per luminaire = 2

Number of luminaires authorised: 1 every 1.55 m

Length (m) – D1 Length in metres of the busbar trunking


Light source Type of lamp.

Fluo tube – Lighting with electronic ballast – Fluocompact - HP fluo – LP sodium – HP sodium – Metal iodide – Incandescent - Halogen

Lamp unit P (W) Unit power in Watts of each light fitting

No. of lamps / fixture Number of lamps per lighting fixture

No. of fixtures Number of lighting fixtures

Ib (A) Total nominal current of the circuit

Ballast power (W) Ballast power, to be added to lamp power depending on type of lamp; entered automatically by My Ecodial L and adjustable manually

Downstream circuit polarity

Polarity of circuit supplying the lighting line: 3Ph+N – 3Ph – 2Ph – 1Ph - Upstream (identical to upstream circuit)

Earthing arrangement TT - IT - TN-C - TN-S - Upstream (=upstream earthing system)

Power (kW) Total power of the lighting circuit

Power factor Lighting circuit total cos phi

Ph/Earth fault max break time Maximum interruption time of a phase to earth fault for a TN-C/TN-S system: 5s - <5s

Environment Various choices are proposed.

Page 3 of 3Lighting


Motors

Motor input parameters

Limitations My Ecodial L only treats three-phase asynchronous motors. This means therefore that DC motors, synchronous motors and single-phase asynchronous motors are not dealt with.

Furthermore, the software is limited to a three-phase polarity without neutral and thus cannot deal with single-phase, two-phase or four-phase (three-phase with neutral) polarities. However, most motors are supplied with three-phase power and are balanced, which means that the neutral is not used. There are some very rare cases, not treated by My Ecodial L, in which the neutral is useful for a three-phase motor (when the motor control circuit uses the phase to neutral voltage, in which case the neutral is distributed).

My Ecodial L does not treat the TN-C or IT with neutral arrangement and thus stipulates TN-S if the user requests a TN-C arrangement and IT without neutral if the user requests an IT with neutral arrangement. Once again, as most motors operate on three phases and without a neutral, it is economical to convert a TN-C into a TN-S arrangement when the neutral is not distributed.

Problems related to motor starting When a motor is energised, a high current peak appears which presents a number of problems. First of all, this high current can cause nuisance tripping of the protection devices. Furthermore, as voltage drop at the motor terminals is equal to the product of the upstream resistances (cables, transformer, etc.) and the motor supply current, a large voltage drop occurs. As a result, voltage may drop at motor terminals to such an extent that the motor can no longer start or the operation of other loads is affected. In some cases, this voltage drop is such that it is perceptible on lighting devices.

To limit the harmful effects of motor starting, a number of systems are used to reduce this current peak by limiting voltage at the motor winding terminals on starting.

There are 7 major types of starting. My Ecodial L deals with 3 of them: direct on-line starting, star-delta starting and soft starting. For more details on these starting types.

4 types of starting are not dealt with: part-winding starting, resistance stator starting, starting by autotransformer and resistance rotor starting of slip-ring motors. For more details on these starting types, see page 78 to 86 of the “Diagram library: Industrial Control Technologies”.

Moreover, some applications require speed control which is implemented by variable speed drives. In this case, the variable speed drive is used for starting. For more details.


Description Content

Page 1 of 7Motors

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All these parameters (with the exception of the number of identical circuits, the system earthing arrangement and the polarity) can be modified via a setting window opened by double-clicking or by clicking on the button in the entry zone. This window presents all the information required for the motor feeder settings classed per component. Among this information, two items are not included in the grid and are therefore not defined above:


Motor power output(kW) Rated mechanical power output of motor in kW

Ib (A) Rated current drawn by the motor. This value is not calculated; it comes from the data base. The user has the possibility of modifying the value using the advanced parameters of the selection guide.

Motor on-load power factor

Rated cos phi of motor on load. Value given as a general indication and that can be modified using the advanced parameters of the selection guide.

Motor efficiency Ratio of mechanical power output to electrical power drawn. Value given as a general indication and that can be modified using the advanced parameters of the selection guide.

Start-up type Motor starting mode Direct on-line – Star Delta - Soft - Variable speed drive for more details

Coordination type Type of coordination of switchgear and controlgear Type1 - Type2 - Totalfor more details

Tripping classThe class of the switchgear and controlgear is taken into account in the selection of components.

Possible values: 5,10A (similar to 5), 10, 15, 20, 25, 30

Circuit polarity My Ecodial L only deals with three-phase motors with no neutral (imposed)


TT - IT without neutral - TN-S - Upstream (=upstream earthing arrangement, except if TN-C or IT with neutral, in which case My Ecodial L stipulates TN-S or IT without neutral, respectively –see limitations)

Istart/In Ratio of the starting current to the nominal current of the motor under steady state operating conditions.

Id"/In

Ratio of the subtransient current generated by the motor when starting to the nominal current. This information indicates whether the motor is of the classic or high-efficiency type, which influences the selection of the protection device. Two possible choices:

<= 19: classic motor > 19: high-efficiency motor

Designation Contents

Manual : the motor is started by the circuit breaker that is used as a control device

Page 2 of 7Motors


The values entered above are not all independent. Thus, if you change one of them you may well change the values of other characteristics.

Motor help

The different types of starting

When a motor is energised, the current inrush is high and may, particularly if the supply line cross-section is insufficient, result in a voltage drop that could affect load operation. There are several types of starters used to reduce peak currents on starting.

My Ecodial L proposes 3 types of starter:

The direct on-line starter

Possible only with a squirrel-cage motor. This is the simplest starting mode in which the motor stator is directly coupled to the network.

Starting current = 5 to 8 times rated current

This type of starter is simple, gives the motor a high starting torque and allows rapid starting, but is not suitable in all cases. The motor power must be low compared to the network power to limit disturbances on the network, the machine must not require gradual starting and it must contain a mechanical device to prevent excessively abrupt starting. If there is a danger for users, this type of starter must be not be used and a system to reduce inrush current or starting torque must be implemented. The system most commonly used is to start the motor at a reduced voltage. See diagram.

Motor control Automatic: the motor is started remotely; the control device is either a contactor or a circuit breaker

Motor feeder architecture

This zone is used to define how the three motor feeder functions are integrated. Three possibilities:

1 product: the three functions are integrated in a single device (Tesys Model U, Integral)

2 products: the three functions are integrated in two products that depend on the type of motor control:

Automatic control: the thermal relay is included in the circuit breaker (examples: Tesys Model U, Integral, GV2ME, GV7, NS100L STR22ME, NS400L STR43ME, NS800N Micrologic, P25M)

Manual control: the thermal relay is external with respect to the GV (examples: GV2, GV3)

3 products: the three functions are provided by three separate products (examples: all fusegear, GV2L, NS800N Micrologic): circuit breaker or fuse + thermal relay + contactor

See also

Page 3 of 7Motors


The star-delta starter

In this case, both ends of each of the three stator windings of the motor must be run to the terminal plate. The principle consists of starting the motor by star-connecting the windings at the mains voltage, thereby decreasing the peak current by a factor of 3. See diagram.

Starting current = 1.5 to 2.6 In

Then, when motor speed has stabilised, the windings are delta-connected. This type of starting is ideal for machines with a low load torque or that start off-load.

However, for this type of starting, the contactors must have higher ratings than direct starting contactors as they operate during the starting phase and thus at currents greater than the nominal current.

The soft starter

The motor is started with a gradually increasing supply voltage, thus allowing smooth starting and reducing the peak current. This type of starter controls the operating characteristics, particularly during the starting and stopping phases, provides thermal protection of the motor and starter and mechanical protection of the driven machine. The inrush current can be set from 2 to 5 ln. This system can be used to start all asynchronous. In addition to controlled starting, it allows gradual deceleration and braked stopping.

My Ecodial L also proposes starting with a variable speed drive, in the Protection-Cable-Variable speed drive-Cable-Motor component. Consult the variable speed drive online help for this component for further details.

Motor help

Relation between electrical power and mechanical power

Equations The following equation is applicable:

Where:

In general, a motor manufacturer indicates in the power column of tables the mechanical power of the motor. Other parameters include:

See also

Pelec electrical power drawn by the motor

Pmeca mechanical power output of the motor

motor efficiency

Page 4 of 7Motors


power factor during motor operation

efficiency

current drawn

rated operational voltage

All these parameters are related by the classic equation:

Where:

This means that the electrical power effectively drawn is greater than the mechanical power indicated in manufacturer catalogues.

How does My Ecodial L operate? For the mechanical power output entered, My Ecodial L draws from a table the efficiency and the power-factor (during motor operation) parameters.

My Ecodial L then calculates:

the electrical power Pelec

the Ib of the motor, i.e. the drawn operational current

Note that though it is not possible to modify the efficiency and power-factor parameters in the selection guide, it is possible in the window for step-by-step calculation.


Motor control and protection

Pmeca mechanical output power of the motor

U rated phase-to-phase voltage

I current drawn

motor power factor

motor efficiency

See also

Page 5 of 7Motors


Level-1 parameters

Parameter Value

Range Circuit-breaker range (Compact, GV or TESYS) or FCU range

Designation Technical name of the circuit breaker or of the FCU

Trip unit / curve Circuit-breaker protection: tripping curve of the circuit breaker or type of trip unit

FCU protection fuse model

Contactor designation Name of the contactor

Thermal relay Catalogue number of the thermal relay.

Protection against fire Protection against fire - Yes or No

If yes, the earth-leakage protection threshold is < 500 mA with a 50 ms or 90 ms time delay

Earth-leakage protection Yes or no

Number of protected poles

Number of interrupted poles (xP) and protected poles (xd)


4P3d+Nr 4 poles interrupted and 3 poles protected, plus neutral protection at 0.5 In



1P1d 1 pole interrupted and protected

See table H1-37 in the electrical installation guide

Thermal setting I (A) Value set for the thermal protection (according to protected load)

Magnetic setting I (A) Value set for the magnetic protection

Trip-unit rating Protection rating

Frame rating Maximum rating for the selected type of circuit breaker, often simply called the frame size or frame rating.

Im (Isd) setting

Dial setting for magnetic protection on front of device

Magnetic setting = factor between magnetic and thermal thresholds

Typical value for Im (Isd) = 6.00 x Ir

Ir setting Dial setting for thermal protection on front of device

Thermal setting = factor between Ir and Io

Page 6 of 7Motors


Return to help on motors

Io setting Dial setting for thermal protection on front of device

Thermal setting as a percentage of the rated current

Motor mechanism Motor mechanism - With or Without

Installation Type of installation - Fixed or Withdrawable

Cascading requested Equipment selection for cascading - Yes or No

Discrimination requested Verification of discrimination - Yes or No

Installation Type of installation Fixed - Draw-out

Short-time setting Time-delay setting for the RCD

See also

Page 7 of 7Motors


Variable speed drives

Variable speed drives A variable speed drive is used in specific applications to control electric motors. It is necessary for installations requiring continuous speed control, with the possibility of overspeeds for a limited period of time, for installations requiring accurate control of acceleration and deceleration and installations requiring high starting and stopping torques. Such applications include pumps, fans, compressors, conveyors, machines with a high load torque and machines with high inertia.

It also allows another type of motor starting over and above those traditionally proposed.


Permissible transient over-torque

Standard torque: the over-torque and the associated overcurrent are limited by the variable speed drive to a typical value of 1.2 to 1 x the nominal current of the variable speed drive for 60 s. This choice optimises the variable speed drive with respect to applications that do not require a high transient torque: centrifugal pumps, fans, conveyors.

High torque: the over-torque and the associated overcurrent are limited by the variable speed drive to a typical value of 1.5 to 1.7 times the nominal current of the variable speed drive for 60 s. This choice allows selection of a variable speed drive adapted to applications requiring a high transient over-torque: handling equipment, crushing mills, pumps with high starting torque.

Values entered or calculated during step-by-step calculations Visible in the variable speed drive input grid

Description Content

Length Length of cable between the circuit-breaker and the variable speed drive


Permissible transient over-torque -V1 Used to define the over-torque level required by the application: high torque - standard (more info)

Motor power output (kW) Nominal mechanical power output of motor in kW

Start-up type Variable speed drive

Motor efficiency Ratio of mechanical power over electrical power drawn

Ib of the motor (A) Current drawn by the motor

On-load power factor Nominal cos phi of the motor on-load

Circuit polarity The polarity of the variable speed drive which can be 3-Ph ou 1-Ph.

Earthing arrangement TT - IT without neutral - TN-S - Upstream (=upstream earthing arrangement, except if it is TN-C or IT with neutral, in which case My Ecodial L imposes a TN-S or IT without neutral, respectively)

Designation Designation of the variable speed drive selected by My Ecodial L

Permissible transient over-torque Used to define the over-torque level required by the application: high torque - standard (more info)

Transient over-torque value (%) The value of the transient over-torque results from the above choice and is expressed as a percent of the nominal torque.

VSD losses (W) Power drawn by the variable speed drive

VSD power drawn (kW) Nominal power of the variable speed drive

Ib consumed by the VSD (including losses) (A) Variable speed drive nominal input current

Maximum deliverable nominal current (A) Output current of the variable speed drive under steady state conditions (A)

Maximum transient current for 60s / 10 min This is the maximum current in amps that a variable speed drive can supply for 60 seconds per 10 minute period. The current is

automatically limited to this value by the drive. If the thermal capacity is exceeded, the drive is automatically protected by a thermal fault

Page 1 of 5Variable speed drives


My Ecodial L is used to size a motor feeder circuit containing a variable speed drive for standard asynchronous motor.

The variable speed drives of the ALTIVAR, ATV38E, ATV 58E and ATV68E ranges are particularly well suited to the requirements of installations, building equipment and infrastructures.

This ready-to-use solution comes in a wall mounted or floor standing enclosure, incorporating the standard features for these installations:

Harmonic compensation

Compliance with EMC standards and recommendations

Energy savings

PI controller incorporated for flow rate or temperature regulation

Remote control

The calculations made are also valid for the standard ranges, provided the catalogue reactor is used with them.

Sizing a circuit for a motor with a variable speed drive FAQ concerning variable speed drives Motor help

FAQ concerning variable speed drives

What is a frequency converter?

A frequency converter is a device used to make the speed of a standard asynchronous motor vary by varying the frequency of the voltages and currents applied to the motor.

Thanks to power electronics, this principle is used in variable speed drives and is suitable for applications in which the need to control the motion of an object or a fluid is essential.

How does a frequency converter work?

The principle is to convert the distributed utility AC power at 50 or 60 Hz into DC power by means of a rectifier assembly and then convert this DC voltage into AC frequency and voltage components, variable thanks to an inverter.

Speed regulation and torque regulation are used to control the speed according to the needs and on-load variations of the motor.

This regulation is performed without need for a sensor on the motor: a standard asynchronous motor is used.

Numerical control performed using increasingly high-performance micro-controllers incorporates algorithms of the “vector flow control without sensor” type.

What is the power factor of a motor supplied by a frequency converter?

Upstream of the converter, current is in phase with voltage and thus the power factor of the assembly is equal to 1.

Note that the power drawn will also depend on the motor rotation speed, given that P=Cw where P is mechanical power, C torque and w the motor shaft speed

Furthermore, given that the input stage is not linear, the converter, although corrected, generates 5th, 7th and 11th order harmonics, etc. The effect is characterised by the form factor.

Why standard torque and high torque?

Some applications require an over-torque during transients, accelerations and decelerations. In this case, a high-torque variable speed drive must be used.

lockout function.

Earthing arrangement TT - IT without neutral - TN-S - Upstream (=upstream earthing arrangement, except if it is TN-C or IT with neutral, in which case My Ecodial L imposes a TN-S or IT without neutral, respectively)

Circuit polarity Three-phase or single-phase

Line inductor Presence of a line inductor upstream of the variable speed drive

Permissible line Isc(kA) Value of the short-circuit current that the variable speed drive can withstand without a line inductor upstream. If a line inductor is present upstream, this value is meaningless and is not displayed.

Cable size downstream of VSD (mm²) This value now comes from the installation manual and is no longer calculated.

IP Degree of protection

See also



For other applications such as centrifugal pumps and fans for example, a standard torque variable speed drive is sufficient.

What calculation principle is used?

The calculation formulas are mainly based on an evaluation of powers consumed.

First, the software calculates electrical power according to the mechanical power of the motor chosen and adds to it the various losses of the components making up the installation.

The downstream current is the current flowing in the motor. The circuit is sized for the most unfavourable case, with the motor supplied at its nominal peak power, torque and speed.

Upstream current is calculated assuming that the motor is supplied at its nominal peak power and allowing for the form factor of the variable speed drive

How is motor thermal protection provided?

The thermal protection of the motor is provided by the variable speed drive.

The variable speed drive permanently calculates the thermal state of the motor according to the current drawn and the efficiency of motor ventilation that depends on speed.

The setting parameter for this protection is lth and must be set to the value of the continuous output current.

How is short-circuit protection provided downstream of the variable speed drive?

The variable speed drive includes a phase to phase and phase to earth short-circuit protection device.

This protection device is designed to protect the variable speed drive against destruction in the event of an accidental short-circuit. However, its very high speed means it also protects the downstream installation.

This guarantees a very high degree of availability of the installation as it is sufficient to eliminate the fault to restart the installation.

How is short-circuit protection provided upstream of the variable speed drive?

In this case, protection is provided by the distribution circuit-breaker in the event of an accidental short-circuit.

Return to variable speed drive help

Sizing a circuit for a motor with a variable speed drive

The following algorithm is used:



of 5Variable speed drives


Variable speed drives help

LV protection devices and variable-speed drives

Protection built into drives

Motor overload protection

Modern variable-speed drives protect motors against overloads.

By instantaneous limiting of the rms current to approximately 1.5 times the rated current.

By continuously calculating I²t, taking into account the speed (because most motors are self ventilated, i.e. cooling is less effective at low speeds).

My Ecodial L takes into account only the situation where for a given feeder, there is one variable-speed drive and one motor. In this case, the motor overload protection of the drive simultaneously provides overload protection for the devices and the cables.

Protection against motor or line short-circuits downstream of the drive

If a phase-to-phase short-circuit occurs at the drive output (or across the motor terminals or at any point on the line between the drive and the motor), the overcurrent is detected in the drive and a locking order is issued very quickly. The short-circuit current is interrupted in a few microseconds, thus protecting the drive. This very short current is essentially supplied by the filtering capacitor for the rectifier and is thus produces no effect on the supply line.

Other protection functions in drives

Variable-speed drives have other self-protection functions against:

Excessive component temperature rise

Dips in network voltage

Overvoltages at the network power frequency

Loss of a phase (three-phase drives)

In the event of a fault, these built-in protection functions provoke drive locking and the motor turns to a stop. The break in supply is ensured by the line contactor which is opened by a relay in the drive.

Variable-speed drives - Sizing a circuit for a motor with a variable speed drive

See also

See also



LV – LV transformers

Input parameters

My Ecodial L incorporates the power sum of the loads downstream of the LV/LV transformer.

Functions These transformers, with power ratings from a few hundred VA to a few hundred kVA, are often used to:

Change voltage: in auxiliary control and monitoring circuits, in lighting circuits (to obtain 230 V when the neutral is not distributed).

Change the earthing arrangement of some loads with high leakage currents or minimum insulation (computers, electric furnaces, heating tools, equipment in industrial kitchens, etc.). Isolation transformers can also be used in zones requiring high energy availability or where there is an explosion risk. They are extensively used to supply operating rooms in hospitals: continuity of supply is vital and the nitrogen monoxide used in these rooms is explosive.

They normally come with the essential internal protection devices (consult the supplier). An overcurrent protection device must be provided at the primary. Their implementation requires knowledge of their specific operating characteristics.

Switching inrush currents When energised, very strong current inrushes occur (known as switching inrush currents), which must be taken into account when defining the overcurrent protection devices. Amplitude depends on when the voltage is applied, residual induction in the magnetic circuit and the transformer characteristics and load.

The first current peak frequently reaches 10 to 15 times the rated RMS current of the transformer and may even, for small powers (< 50 kVA) reach values 20 to 25 times the nominal current. This inrush current is very quickly damped with a time constant of around a few ms to a few dozen ms.

Choice of protection of a feeder supplying an LV – LV transformer

The protection device placed on a feeder supplying an LV – LV transformer must not be subject to nuisance tripping when the transformer is energised. Consequently the following are used:

Selective circuit-breakers (thus time-delayed)

Page 1 of 3LV – LV transformers

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Circuit-breakers with a high tripping threshold

My Ecodial L chooses circuit-breakers adapted to protection of LV/LV transformers.

The primary is sometimes protected using aM type fuses. This solution has two drawbacks: the fuses must be very highly overrated (at least 4 times transformer nominal current) and to perform the control and isolation functions at the primary, they must be combined with a switch or contactor which must also be very highly overrated.

LV/LV transformer input parameters


Caution: in the input field, the sign indicates that My Ecodial L will look for values in its LV/LV transformer database.

These values cannot be modified subsequently.

Description Content

LV/LV transformer polarity My Ecodial L proposes three-phase or single-phase transformers.

Transformer nominal power (KVA) Transformer power in kVA. Choose from the list proposed

Secondary Ph-Ph V (V) Phase to phase nominal voltage at the secondary of the LV/LV transformer

Short-circuit voltage (%) Transformer short-circuit voltage.

Downstream circuit polarity 3Ph+N – 3Ph – 2Ph – 1Ph - Upstream

Earthing arrangement Earthing arrangement at the secondary of the LV/LV transformer TT - IT - TN-C - TN-S - Upstream (= as defined in the general characteristics)

LV/LV transformer ambient temperature (°C)

Allows for transformer derating. My Ecodial L does not handle values greater than 40°C. If necessary, contact your Schneider Electric representative.

Connection Reminder of the connection designation for the transformer chosen. Also visible in the choice guide.

Copper losses (W) copper losses values.



LV-LV transformer help

Inrush current (x In) Reminder of the value of the LV/LV transformer inrush current peak. Value read in the LV/LV transformer database and used for calculation. This field cannot therefore be modified. Also visible in the choice guide.

Neutral electrode resistance Rs (Ohm)

Value of the neutral electrode resistance in Ohm (any value). Displayed depending on the earthing system.

Earth electrode resistance (Ohm)

Value of the earth electrode resistance in Ohm (any value). Displayed depending on the earthing system.

See also



Power sum

General presentation

Objectives

1. size the source

2. calculate the current flowing in the distribution circuits (feeder circuits not used for final loads)

3. initialise the data required for the selection of the capacitor bank

Method

The power sum is in fact a current sum. It is the algebraic sum of the currents and the apparent powers that is carried out, covering each piece of equipment right up to the source. This method is approximate compared to a sum of the active an reactive powers, or a load flow calculation, however it has an advantage in that it oversizes the installation. In this type of calculation, accuracy is not of critical importance given the application of highly approximate correction factors (Ks and Ku).

Description of the correction factors

Use factor (Ku):

the use factor expresses the proportion of time that a load is in operation. It is used to determine the current flowing in the upstream circuits and to size the source. It is however not taken into account for the selection of circuit protection devices.

Load factor (Kch):

the load factor expresses the proportion of full rated load at which the load operates. This factor is not used in My Ecodial L but it is always possible to indicate the estimated value of the load current or power rather than the full rated load current or power.

Diversity factor (Ks):

the diversity factor expresses the level of use of the installation, in particular for motors and power sockets. It therefore requires detailed knowledge of the installation in question. It is used to select the busbar assembly or BTS to which it is assigned, to determine the current flowing in the upstream circuits and to size the source.

Page 1 of 2Type 1 and type 2 coordination

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Future extension factor

this factor takes into account the predicted evolution of the installation. It does not exist in My Ecodial L.

Page 2 of 2Type 1 and type 2 coordination

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My Ecodial L Certification

Calculation standards My Ecodial L 3 complies in all aspects with the European CENELEC R064-003 report, used in France in drafting the UTE C 15-500 guide.

This report serves as the reference document in sizing many components in electrical installations. My Ecodial L respects all applicable rules in calculating the sizes of conductors and in selecting the suitable protection devices, whatever the type of conductor or protection device.

Field of application My Ecodial L 3 may be used exclusively for low-voltage installations where the circuits are made up of insulated conductors, cables or busbar trunking systems.

My Ecodial L 3 takes into account all the parameters required to meet the installation standard, the main parameters being:

Operational currents (taking into account harmonics)

Permissible currents for conductors

Protection-device characteristics for overload protection

Thermal constraints for conductors during short-circuits or a fault

Protection against indirect contacts

Reduction in the voltage drop

Short-circuit currents and fault currents

My Ecodial L certification The parameters in the UTE C15-500 guide are specifically designed to enable checks on calculation software for insulated conductors, cables and the selection characteristics for busbar trunking systems.

My Ecodial L 3.35 passed the certification tests organised by UTE, an independent certification organisation.

The certification number is 15L-602A / 15L-602 (click the number to display a copy of the UTE certifications, Acrobat reader is required).

Field of application for UTE guides

UTE has successively published two guides, UTE C 15-500 and UTE C 15-105

Guide UTE C 15-500 is intended to serve as a basis for writing software. It provides complete equations and in-depth information on calculations. The guide for 2003 changed names and became "Détermination des sections des conducteurs et choix des dispositifs de protection à l'aide de logiciel de calcul" (Determining conductor sizes and selection of protection devices using calculation software).

Guide UTE C 15-105 provides one very rigorous method and two rough calculation methods. The two rough calculation methods are:

the composition method the conventional method.

The rigorous method calculates the impedances.

"Application of guide UTE C 15-500 produces results that differ from those obtained using the methods in guide UTE C 15-105. These differences in the calculation results between the old and new software do not mean that installations calculated using the old rules are not satisfactory. Though guide UTE C 15-500 takes into account certain parameters more accurately, others remain highly arbitrary, such as the factor c, or equiavalent, such as the resistance of connections, the impedance of switchgear, arc impedances in maximum short-circuits, the real length of circuits, etc." J3E Review, August/September 2003.

Correction factors in NFC 15-100, edition 2003

Earthing arrangements

The notion of indirect contact

See also

Page 1 of 13My Ecodial L Certification

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Diagram A1

Definition:

Contacts between people and accidentally energised exposed conductive parts (insulation fault).

Effect:

Passage of current in the body of the person Risk of electrocution

Protection:

The installation standards (IEC 364, NF C 15-100, etc.) define three earthing arrangements, TN, IT and TT, and the relevant installation and protection rules.

Earthing arrangements

The 1st letter describes neutral earthing

The 2nd letter describes exposed conductive part earthing



Diagram A2

TN system - exposed conductive parts connected to earthed neutral

Diagram A3

A "phase to earth" insulation fault causes a high fault current (only limited by Zph-PE)

A short-circuit protection device (SCPD) must then be used to de-energise the circuit:

Circuit-breaker: Magnetic tripping threshold (Im) < If

Fuse: Elimination of lf within a time shorter than that given by the safety curves

Use of a residual current device

If = 0.8 U0 / (Rph + RPE)

IT system - isolated or impedance-earthed neutral



Diagram A4

First insulation fault. No risk If » 0 A

Second insulation fault: If = 0.8 U0 / 2(Rph + RPE)

High "phase to phase" or "phase to neutral" fault current (only limited by Zph-PE and Zn - PE)

A SCPD must then be used to de-energise the circuit:

Circuit-breaker: Im < If

Fuse: Elimination of lf within a time shorter than that given by the safety curves

Use of a residual current device

The TT arrangement – Earthed neutral

Diagram A5

A "phase to earth" insulation fault causes a weak fault current (extremely limited by the earth resistances Rb and Ra)

The fault resembles an overload, but the circuit-breaker’s thermal protection tripping time is too long (a few seconds):

A Residual Current Device (RCD) should be used.

If = U0 /(Ra + Rb)



Earthing arrangement selection

XML export

My Ecodial L now offers a new export format, XML, accessible via the File menu.

This command can be used to export:

All the characteristics of the devices in the installation

The detailed structure of the electrical diagram.

Schneider Electric has joined forces with its partner Algotech Informatique to ensure that this information can be used to automatically generate an electrical diagram that is much more useful when the designer transmits the file to the installers. Automation saves considerable time when preparing the file. What is more, certain diagrams are pre-formatted, thus ensuring additional time savings.

Algotech Informatique offers a range of professional drafting software.

Example of automatic generation

My Ecodial L project

Criteria TT TN IT

Economic solution

Ease of detection and elimination of an insulation fault

Low stresses on equipment during faults

No specially trained personnel

Safety against the risk of fire

Continuity of supply

Safety of persons

Web site www.algotech.fr

Information [email protected]

Address Espace entreprises Izarbel1, Technopole Izarbel, 64210 Bidart



The export command automatically produces the following.

Diagrams accepted and refused by My Ecodial L

Simple accepted networks Refused networks Accepted networks with BTS



Refused networks with BTS

Simple accepted networks

Accepted normal/replacement networks N: Normal

R: Replacement

You can also reverse the positions of the transformers or generators with any source in the diagram, or reverse the normal and replacement roles.



In this last diagram, the role of the normal or replacement source can be reversed. Moreover, you can place up to 4 generators and 4 transformers.



Refused networks 2 parallel-connected branches with a circuit between the main LV board and the source circuit.



5 transformers on the same busbasr:

Direct connection between two busbars:



Dual replacement level:

Accepted networks with decentralised type BTS



Refused networks with decentralised type BTS With several sources, the network is always refused:

Supply of a decentralised type BTS by a generator is prohibited:



Supply of the BTS by a replacement supply source is impossible

Generator help Transformer help Any source help BTS help

See also



Harmonic distortion (current)

Definition Standard NFC15-100 introduces the notion of THDI, i.e. Total Harmonic Distortion of Current.

In a three-phase system with a neutral, the odd multiples of the third-order harmonic H3 (H3, H9, H15, etc.) do not cancel each other out in the neutral. There is therefore a flow of current in the neutral greater than that in the phases. Depending on the level of harmonic distortion, it may be necessary to modify the size of the neutral conductors.

This stipulation replaces the notion of the loaded neutral in the previous versions of the standard.

For current harmonics, harmonic distortion is calculated using the equation below.

THDI measurement The THDI characterises the deformation of the current wave. The disturbing device is located by measuring the THDI on the incomer and each outgoer of all the various circuits in order to detect the source of the problem.

Typical THDI values and their impact on the electrical installation

A value under 15% is considered normal. Malfunctions are not a risk. The neutral conductor is not considered loaded.

A value between 15% and 33% signals significant harmonic pollution. There is a risk of temperature rise, which requires oversizing of the cables and sources. The neutral conductor is considered loaded.

A value above 33% reveals major harmonic pollution. Malfunctions are probable. An in-depth analysis and the use of special protection devices are required or, in some cases, harmonic-attenuation systems may be the best solution.

Summary of NFC15-100 rules for calculation of the neutral Origin of harmonics Cable input parameters

See also

Page 1 of 4Harmonic distortion (current)

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Origin of harmonics

Harmonics are created by non-linear loads that draw current in the form of impulses and not a sinusoidal wave. Non-linear loads come from rectifier-type and diode-bridge power supplies or from the ballast of fluorescent lamps.

Definition of non-linear loads

A load is said to be non-linear when the current drawn does not have the same waveform as the supply voltage.

Typical examples are loads comprising power electronics. They are increasingly numerous in low-voltage networks, not only in office buildings, but in industry as well.

Examples are: industrial equipment (welding machines, arc furnaces, induction furnaces, rectifiers, etc.) variable-speed drives for asynchronous motors office machines (computers, photocopy machines, etc.) household appliances UPSs

Cable input parameters Definition of harmonic distortion of current (THDI)

Summary rules for neutral sizing

NF C 15-100 (S = cross-sectional area)

Voir aussi

THDI <= 15% 15% < THDI £ 33% THDI >= 33%

Single-phase circuits Sneutral <= Sphase Sneutral <= Sphase Sneutral = Sphase

Three-phase circuits + neutral

Multicore cables

Sphase <= 16 mm² Cu or 25 mm² Al

Sneutral = Sphase Sneutral = Sphase

Factor 0.84

Sneutral = Sphase

Sneutral decisive

Ibneutral=1.45 x Ibphase

Factor 0.84

Three-phase circuits + neutral Sneutral = Sphase



IEC 60364

Multicore cables

Sphase > 16 mm² Cu or 25 mm² Al

Sneutral = Sphase/2 is permissible

Neutral protected

Sneutral = Sphase

Factor 0.84

Sneutral decisive


Factor 0.84


Single-core cables

Sphase > 16 mm² Cu or 25 mm² Al

Sneutral = Sphase/2 is permissible

Neutral protected

Sneutral = Sphase

Factor 0.84

Sneutral > Sphase

Sneutral decisive


Factor 0.84

THDI <= 15% 15% < THDI <= 33% 33% < THDI <= 45% THDI >= 45%

Single-phase circuits

Sneutral <= Sphase

Sneutral <= Sphase Sneutral = Sphase Sneutral = Sphase


Multicore cables

Sphase<= 16mm² Cu or 25mm² Al

Sneutral = Sphase

Sneutral = Sphase

Factor 0.86

Sneutral = Sphase

Sneutral decisive

Ibneutral=3xTHDIxIbphase

Factor 0.86

Sneutral = Sphase

Sneutral decisive



Multicore cables

Sphase > 16mm² Cu or 25mm² Al

Sneutral = Sphase/2 admis

Protected neutral

Sneutral = Sphase

Factor 0.86

Sneutral = Sphase

Sneutral decisive


Factor 0.86

Sneutral = Sphase

Sneutral decisive



Single-core cables

Sneutral = Sphase/2 admis

Sneutral = Sphase

Sneutral > Sphase

Sneutral decisive

Sneutral > Sphase

Sneutral decisive



But what if the level of harmonic distortion is not known? For sites other than residential, with three-phase circuits + neutral and when the level of harmonic distortion is not supplied by the user, the designer should adopt the rules below.

The size of the neutral conductor must be equal to that of each phase (taking into account the factor of 0.84).

The neutral conductor must be protected against overcurrents and be interrupted.

In the absence of the necessary information, this rule must be strictly applied.

Origin of harmonics Cable input parameters Harmonic distortion of current

Sphase > 16mm² Cu or 25mm² Al

Protected neutral Factor 0.86 Ibneutral=3xTHDIxIbphase

Factor 0.86


See also



Curve direct - Display of tripping curves

Click the button in My Ecodial L to launch the independent Curve Direct module.

This module displays all the devices upstream of the device selected in the diagram.

Display the tripping curves of the devices selected by My Ecodial L

Procedure

1. Select the most downstream device in the diagram.

2. Click to launch the Curve Direct module.

It is also possible to select in the circuit-breaker database the devices for which you wish to see the tripping curves (More information).

Input parameters

Curve direct - User manual

See also

Page 1 of 8Curve direct - Display of tripping curves


Select a device

1. Click the Plus button.

2. Select a device in the list.



The operating and non-operating curves are displayed (tripping curves).



3. Adjust the dial settings, the curves are automatically updated.

Shift from one curve to another

When a number of devices have been selected, it is possible to shift from one device to another by clicking the

button.

Select the device to make its curve active.



Modify the device or a trip unit

Click the button to display the characteristics of the active device.

It is then possible to modify the device or the trip unit as needed.



Print the active curves

Click the button to open the standard printing window.

Delete a device

Click the button to display the list of devices for which the tripping curves are displayed.

It is then possible to delete a device.



Quit the module

Click the button to close the window and the Curve Direct module.

Caution

When Curve Direct is used independently, no data is saved and no message requests confirmation of closing. Check that all data has been printed before closing the module.

When Curve Direct is launched from My Ecodial L, the program asks if you wish to save any modifications made using Curve Direct.

If you decide to save any modifications, My Ecodial L saves the settings and shifts to manual mode. When the installation is recalculated, My Ecodial L will check that the modifications are compatible with all rules and standards on protection against direct and indirect contacts.

If you decide not to save the modifications made using Curve Direct, no changes are made in My Ecodial L. The modifications made using Curve Direct are lost.



If you exit Curve Direct by clicking the Close button , the program does not request confirmation before closing and any modifications made using Curve Direct are not saved.

Display of tripping curves

See also



My Ecodial L Technical Documentation V3.4

Documents

Transcript of My Ecodial L Technical Documentation V3.4