MPC-20 MPC-50 Indirect Earth Simulator Manual

7/26/2019 MPC-20 MPC-50 Indirect Earth Simulator Manual

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STEP AND TOUCH VOLTAGE TESTER

GROUND RESISTANCE

TESTER

MPC-20 (20 A) code 7 70 123

MPC-50 (50 A) code 7 70 075

INSTRUCTION MANUAL

( M98113601-20 / 03A )

(c) CIRCUTOR S.A.


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--- MPC 20 & 50 TESTER - M-981136 (vers. BD) --- Page 2

1.- MPC-20 - MPC-50 .................................................................... 41.1 Usual operating procedure 41.2 Precautions whilst operating 5

2.- DESCRIPTION OF THE MAIN COMPONENTS ...................................... 62.1 Source of regulated voltage 62.2 Control and protection circuit 62.3 Voltage and current tester 62.4 Touch electrodes 62.5 Accessories 6

3.- CONTROL AND CONNECTION FEATURES OF THE MPC-20 / MPC-50 .... 73.1 Control Components 73.2 External connection components 7

3.3 Internal connection components 8

4.- MAIN FEATURES ............................................................................. 104.1.- Power supply 104.2.- Dimensions, weight:5.1.1 Attaching the equipment 144.3.1 Features as a step and touch voltage tester. MPC-20 TESTER 114.3.2 Features as a step and touch voltage tester. MPC-50 TESTER 124.4.- Features as an ground resistance tester 13

5.- TESTING STEP OR CONTACT VOLTAGE............................................ 14

5.1 Installation and start-up 145.2 Attaching the MPC-20 / MPC-50 145.3 Auxiliary ground for current injection 145.4 Connecting the current circuit 165.5 Connecting the power supply 165.6 Setting the maximum default current 175.7 Attaching the testing electrodes 185.8 Button for testing erratic currents 185.9 Adjusting the current and testing the

STEP or TOUCH VOLTAGE 195.10 Test results 20

6.- TESTING GROUND RESISTANCE ..................................................... 216.1 Attaching and connecting the MPC-20 / MPC-50 226.2 Attaching the "MEASURING ROD" 226.3 Testing erratic voltages 226.4 Testing ground resistance 226.5 Test results 236.6 Repeating tests 24


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CHAPTER II

7.- EXISTING STANDARDS ................................................................... 257.1 Abstract and table of voltages 257.2 Standards relating to the MPC-20 / MPC-50 26

8.- CORRECTION OF THE READ OUTS .......................................................... 279.- MAINTENANCE............................................................................... 2910.- TECHNICAL SERVICE ..................................................................... 29


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MPC-20 & MPC-50

1.- PRELIMINARY WARNINGS:

1.1.- USUAL OPERATING PROCEDURE

The MPC-20 and MPC-50testers are compact and robust and aredesigned to test where large powers are needed for a short period of time:

- MPC-20: up to 12 kVA

- MPC-50: up to 20 kVA

Its microprocessor controlled testing system ensures that tests are madein approximately 10 seconds.

Its portability means that weight has been kept to a minimum with theuse of minimal loss toroidal transformers.

Heat generated by the transformer windings is continuously eliminatedby an in-built ventilation system. It is able to operate indefinitely, making 12 sec.tests at 40 sec. intervals. If for any reason it overheats, a red indicator light willshow why and will prevent it from operating until normal temperature is re-established.


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1.2.- WARNINGS!

THE CURRENT USED FOR MEASUREMENTS, 20 A with the MPC-20 and 50 A in the MPC-50, IS SUFFICIENT TO CREATE SIGNIFICANT

VOLTAGES AROUND THE ELECTRODES, ESPECIALLY THE AUXILIARYELECTRODES.

PLEASE TAKE ALL NECESSARY PRECAUTIONS TO AVOIDACCIDENTS.

For example: A 5 Ohms auxiliary electrode creates a voltage of 250 V arounditself.

VOLTAGE MAY REACH 600 V AROUND THE CABLE OUTPUT with theMPC-20 and 400 V with the MPC-50.

THE POWER CIRCUIT CONNECTIONS MUST NEVER BE

HANDLED WITHOUT HAVING FIRST STOPPED THE EQUIPMENT ANDREMOVED THE OPERATING KEY.

BEFORE ANY MEASUREMENTS ARE TAKEN, SIGNS MUST

PREVENT PEOPLE FROM PASSING THROUGH OR REMAINING IN THEINJECTED CURRENT AREA. IN THE EVENT OF HIGH GROUNDRESISTANCES, VOLTAGES UP TO 600 V MAY BE CREATED, WHICH ARE

FATAL TO ANIMALS OR PERSONS NEAR TO THE DISPERSERS DURINGTESTS.


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2.- DESCRIPTION OF THE MAIN COMPONENTS

2.1.- VOLTAGE SOURCE

MPC-20:voltage source, with 10 regulating scales using a switch and

fine adjustment using a dial. Supplies a regulable voltage between 0 and 600 Vand is set for a current of 20 A. It can test to 20 A in installations with a 30Ohms resistance (ground and auxiliary added).

MPC-50:voltage source, with 8 regulating scales using a switch and fineadjustment using a dial. Supplies a regulable voltage between 0 and 400 V andis set for a current of 50 A. It can test to 50 A in installations with a 8 Ohmsresistance (ground and auxiliary added).

The remaining components are the same in each:

2.2.- CONTROL AND PROTECTION CIRCUITButton for testing erratic currents. Two directional selector key to control thecurrent injection (0 and 180): Line voltage indicator. Over heating indicator.Fuse protection for the operating circuit Protective circuit breakers for all theequipment and for the output circuit.

2.3.- VOLTAGE AND CURRENT TESTER, controlled by micro-processor. Ittest and also calculates Vp, Vc and Rt. The alphanumeric liquid crystal displayshows preset data, measurements and calculations.

2.4.- TOUCH ELECTRODES, that are cylindrical, 200 square cm at the baseand weigh 250 N, with carrying handles and terminals for connecting the testingcables.

2.5.- ACCESSORIES. 50 metre cables, 10 mm in diameter with terminals forcurrent injection. 50 metre cables for voltage reading. Bridging cable to join thetwo touch electrodes.


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3.- CONTROL AND CONNECTION COMPONENTS OF THE MPC-20 & MPC-503.1.- CONTROL ELEMENTS

1 VOLTAGE OUTPUT SWITCHMPC-20: FROM 1 TO 10

MPC-50: FROM 1 TO 8

SwitchPosition

MPC-20 MPC-50

1 0 to 60 V 0 to 50 V

2 0 to 120 V 50 to 100 V

3 20 to 180 V 100 to 150 V

4 180 to 240 V 150 to 200 V

5 240 to 300 V 200 to 250 V

6 300 to 360 V 250 to 300 V

7 360 to 420 V 300 to 350 V8 420 to 480 V 350 to 400 V

9 480 to 540 V

10 540 to 600 V

2 FINE REGULATION CONTROL (according to previous table)3 RED TEMPERATURE INDICATOR4 RED SYSTEM VOLTAGE INDICATING LIGHT5 ANALOGUE AMMETER FOR ADJUSTMENT AND ASSISTANCE6 GENERAL AND OUTPUT CIRCUIT BREAKER7 SELECTOR WITH KEY OPERATE THE TEST

8 LIQUID QUARTZ DISPLAY9 3 BUTTONS TO PRESET Imax VALUE10 BUTTON TO SELECT OPERATING MODE (Vp/c or Rt)11 BUTTON FOR ERRATIC VOLTAGE MEASUREMENTS

999999999999

ENTERENTERENTERENTER MODEMODEMODEMODE

3.2.- EXTERNAL CONNECTION COMPONENTS

12 OUTPUT TERMINALS: MAX 50 A, MAX 600 V13 VOLTAGE INPUT TERMINALS TO THE VOLTMETER


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3.3.- INTERNAL CONNECTION COMPONENTS

MPC-20:

30 AND 31 SINGLE PHASE POWER SUPPLY: 230 VT.T TERMINAL WITH OBLIGATORY EARTHING CONNECTION

MPC-50:

30 AND 32 SINGLE PHASE POWER SUPPLY: 400 V30 AND 31 SINGLE PHASE POWER SUPPLY: 230 V (EXCEPTIONAL)T.T TERMINAL WITH OBLIGATORY EARTHING CONNECTION

SIZE:


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Control panel:

999-> 999 ENTER ESC

RT-VPC0 OFF 180

(LLAVE)

ERRATICAS

ENTRADA TENSION

Vm

PILOTO RED

PILOTO TERMICO

CONMUTADOR DESALIDAS 1 AL 8

1

2

0

50

AMPERIMETRO

INT. GENERAL

DISPLAY

VOLTAGE INPUT

CIRCUIT BREAKER LIGHT

SYSTEM LIGHT

GENERAL SWITCH

AMMETER

OUTPUT 1 TO 8SWITCH

ERRATICS

(KEY)


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4.- MAIN FEATURES

4.1.- POWER SUPPLY

POWER SUPPLY MPC-20 MPC-50

VOLTAGE

FREQUENCY

MAXIMUM CURRENT

CIRCUIT BREAKERPOWER SUPPLY CABLEMAXIMUM POWER

230 10 %SINGLE PHASE

50 / 60 Hz

54 A

100 A2 X 10 + 6 T.T.12 kVA

400 10 %SINGLE PHASE230 V exception50 / 60 Hz

57 A to 400 V(95 A to 230 V)

100 A2 x 16 + 16 T.T.20 kVA

4.2.- SIZES AND WEIGHT

SIZES:HEIGHT 800 mmWIDTH 550 mm

LENGTH 500 mm

WEIGHT: 142 Kg WITHOUT ELECTRODES

ELECTRODE SIZES:

HEIGHT 210 mm APPROX.

DIAMETER 160 mm APPROX.

WEIGHT: 25.5 Kg EACH


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4.3.- TESTING STEP AND CONTACT VOLTAGE4.3.1.- MPC-20 TESTER

CURRENT 0 20 A REGULABLE

OVERVOLTAGE 1, 1 In, 1 Min

VOLTAGE 0 600 V,10 SCALES AND FINE ADJUSTMENT

MAX. RESISTANCE 30 OHMS (GROUND TESTED + AUXILIARYGROUND)

RESISTANCE OFHIGHER VALUES

ALLOWS TESTING AT LOWER CURRENTS

METHOD USED INJECTION AND TESTING OF CURRENT(Ip)

TESTING VOLTAGE IN SURFACE AREA(Vm)

DEFAULT SETTING Imax CALCULATES: Vp/c=Vm xMax/Ip

ANALOGUE AMMETER CLASS: 1.5 RANGE: 20 A

DIGITAL AMMETER CONTROLLED BY MICROPROCESSORACCURACY: 0.5 % MEASUREMENTS 2

digits MAX. : 99.9 A RESOLUTION : 10 mA

MINIMUM READING : 20 mADIGITAL VOLTMETER CONTROLLED BY MICROPROCESSOR

SCALES : 30 V and 600 V SCALE CHANGE : AUTOMATICACCURACY: 0.5 % MEASUREMENTS 2

digits MINIMUM READING : 20 mV IMPEDANCE CUR. : 1000 ohms or 600

kohms (switch) RESOLUTION : 10 mV

MAX. PROGRAMMABLE

CURRENT VALUE

9999 A

SELECTION OPERATINGMODE (Vp/c or Rt)

BY BUTTON (MODE) + Rt/Vp-c Selector

DEFAULT CURRENTPRESELECTION

BY BUTTONS

TESTING ERRATICVOLTAGES

VOLTMETER CONTROL BY BUTTON

CONTROL OF STOP ANDSTART

BY SELECTOR WITH KEY:ON 0--- OFF --- ON 180


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4.3.2.- TESTING STEP AND CONTACT VOLTAGE: MPC-50 TESTER

CURRENT 0 50 A REGULABLE

OVERVOLTAGE 1, 1 In, 1 Min

VOLTAGE 0 400 V,8 SCALES AND FINE ADJUSTMENT

MAX. RESISTANCE 8 OHMS (GROUND TESTED + AUXILIARYGROUND)

RESISTANCE OFHIGHER VALUES

ALLOWS TESTING AT LOWER CURRENTS

METHOD USED INJECTION AND TESTING OF CURRENT(Ip)

TESTING VOLTAGE IN SURFACE AREA(Vm)

DEFAULT SETTING Imax CALCULATES: Vp/c=Vm x Max/Ip

ANALOGUE AMMETER CLASS : 1.5 RANGE : 50 A OVERRANGE : 300 A


digits MAX. : 99.9 A RESOLUTION : 10 mAMINIMUM READING: 20 mA

DIGITAL VOLTMETER CONTROLLED BY MICROPROCESSOR SCALES : 30 V and 500 V SCALE CHANGE : AUTOMATICACCURACY: 0.5 % MEASUREMENTS 2

digits MINIMUM READING: 20 mV IMPEDANCE CUR. : 1000 ohms or 600

kohms (switch) RESOLUTION : 10 mV

MAX PROGRAMMABLECURRENT VALUE

9999 A

SELECTION WORKMODE (Vp/c or Rt)


DEFAULT CURRENTPRESELECTION

BY BUTTONS



CONTROL OF STOP ANDSTART

BY SELECTOR WITH KEYON 0-- OFF --- ON 180

4.4.- TESTING GROUND RESISTANCES(USING CURRENTS UP TO 20 A or 50 A)


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METHOD USED INJECTION AND TESTING OF CURRENT

MPC-20 : 0 20 A

MPC-50 : 0 50 A

TESTING VOLTAGE BETWEEN GROUND AND NEUTRAL AREA(Vm)CALCULATES: Rt.=Vm/Ip

ELECTRODES NEEDED GROUND TO MEASURE DISTANT AUX ELECTRODE "ROD" ELECTRODE FOR TAKING

VOLTAGE

MAXIMUM ERROR 3 % OF MEASUREMENTS 2 digits


digits MAX. : 99.9 ARESOLUTION : 10 mA MINIMUM READING: 20 mA

DIGITAL VOLTMETER CONTROLLED BY MICROPROCESSOR RANGES : 30 V and 500 V RANGE CHANGE : AUTOMATIC

ACCURACY: 0.5 % MEASUREMENTS 2 digits MINIMUM READING: 20 mV IMPEDANCE CUR. : 600 kohms RESOLUTION : 10 mV

SELECTION WORKMODE (Vp/c or Rt)




CONTROL OF STOPAND START

BY SELECTOR WITH KEYON 0-- OFF --- ON 180


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5.- TESTING STEP OR CONTACT VOLTAGE

5.3.- INSTALLATION AND START-UP

This manual contains information and warnings that must be followed by theuser to ensure the safe operation of the equipment and to maintain it in a safecondition.

Usual operation must not be started until the final assembly of the cablesand weights, as recommended in section 1.2.- Connection instructionsof thismanual.

If the equipment is used in a way not specified by the manufacturer, theprotection of the equipment and the people operating it may be

compromised.

When it is likely that there has been a loss of safety (e.g. when damage isvisible), the equipment must be disconnected from the power supply. In theevent please contact a qualified service representative.

5.4.- ATTACHING THE MPC-20/ MPC-5

To test correctly, the MPC-20 or the MPC-50 must be placed 20 or more

metres from the ground to be tested. Do not place it in the area occupied by theelectrodes in the ground.

5.5.- AUXILIARY GROUND FOR CURRENT INJECTION

There must be auxiliary ground for current injecting 50 or more metres awayfrom the ground to be tested Resistance between the auxiliary ground added tothe ground to be measured must not exceed 8 ohms for the MPC-50 and 30Ohms for the MPC-20.

-----------------------------------------------------------------


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DIAGRAM FOR TESTING STEP VOLTAGE

-----------------------------------------------------------------------------------------------------------

DIAGRAM FOR TESTING CONTACT VOLTAGE

GROUND

TO BETESTED

1 metre

Testedvoltage

L (minimum 20metres)

Test intensity lp

AUXILIARYGROUND

L (minimum 20 metres)

GROUND

TO BE

TESTED

Metal parts

Tested

voltage

L (minimum 20

metres)

Test intensity lp

AUXILIARYGROUND


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5.6.- CONNECTING THE CURRENT CIRCUIT

ENSURE THAT THE SELECTOR (ON-OFF-ON) ON THE

MPC-20 & MPC-50 IS DISCONNECTED AND WITHOUT THE KEY.

Connect the "OUTPUT CABLES": to the ground to be measured and theother to the auxiliary ground.

5.7.- CONNECTING THE POWER SUPPLY

5.7.1.- POWER SUPPLY FOR THE MPC-20:

Connect the supply cable to a 230 V II+TT system or an independentgenerator with the same VOLTAGE.

5.7.2.- POWER SUPPLY FOR THE MPC-50:

Connect the supply cable to a 400 V II+TT system or an independentgenerator with the same VOLTAGE (As an exception the MPC-50 may beconnected to 230 V).


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5.8.- SETTING THE MAXIMUM DEFAULT CURRENT

Once the connections described above have been made and after takingSAFETY MEASURES, testing can be done in the following way:

Place the regulator on the "0%" position.

Place the Voltage switch on position "1".

CONNECT THE MPC SWITCH. The model type and the version of thesetting will appear on the display.

Place the "OPERATING MODE" selector on "V p/c".(Connect the 1000 Ohms resistance switch located on the back of the

equipment: voltmeter internal impedance of 1000 ).

PRESS the upper right "MODE" button (operating mode) and the display isready to start testing voltage ("V") or resistance ("Rt"). Use the said button toselect "V" on the display.

MAXIMUM CURRENT must be entered as preset in the installationprocedure. The value in A of the maximum current must be entered as a testingconstant. This value must be supplied by the electricity supply companyaccording to MIE-RAT-19.

Using the 3 buttons above the display, (, and Enter), SET THEMAXIMUM DEFAULT CURRENT (maximum 9999):

a.- To enter setting, press () . The first lx digit will flash.

b.- To enter or change this value press () repeatedly: the digit flashingat that time will increase.

c.- When the required value appears on the screen move on to the nextdigit by pressing (), and so on changing the remaining values.

d.- To enter press (Enter) button.


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5.9.- ATTACHING THE TESTING ELECTRODES

- Attach the touch electrodes (25 kg weights) in a suitable place to starttesting:

STEP VOLTAGE

Attach the two touch electrodes 1 metre apart and near to the ground to betested. Each electrode are joined by a different cable from the voltmeter.

TOUCH VOLTAGE

Attach the two electrodes together 1 metre from the vertical of the testedobject, both connected by a single cable from the voltmeter. The othervoltmeter cable is connected to the tested object with a crocodile clip.

NUMBER OF TESTS

To ensure that there are no dangerous step or touch voltages, it isnecessary to take many measurements within the test area as well as onneighbouring land. To do this, it is useful to have a plan of the installation withdistances of 1 metre marked on it.Whilst testing touch voltage, one must be aware of the possible transmission ofdangerous voltages away from the ground electrode via long metallic structures(metal fences, pipes, rails etc). Testing must be done further away from theseconductive devices.

5.10.- TESTING VOLTAGES DUE TO STATIC CURRENTS

Prior to starting, press the "ERRATIC VOLTAGES" button (keeping itpressed down).

If the Vm value remains at 0 V the presence of erratic voltages andcurrents will be ruled out. If any value appears, it must be noted to

subsequently compare it with the 20 A and 50 A measurements and tomake the appropriate numerical corrections).(See section 8 "CORRECTING READ OUTS").


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5.11.- ADJUSTING THE CURRENT AND TESTING OF STEP OR TOUCHVOLTAGE

Turn the key in one of the two directions and keep it there.

BEFORE TURNING THE SELECTOR MAKE SURE THAT NO ONE IS

USING THE POWER OR TESTING CIRCUIT. PREVENT PEOPLEREMAINING OR PASSING THROUGH THE AREA WHERE THE CURRENTIS TO BE INJECTED BY USING THE APPROPRIATE SIGNS. IN THE EVENT

OF HIGH GROUND RESISTANCES, VOLTAGES UP TO 600 V MAY BECREATED, WHICH ARE FATAL TO ANIMALS OR PERSONS NEAR TO THEDISPERSERS DURING TESTS.

Adjust the current to 20 A with the MPC-20 and 50 A or slightly higherfor the MPC-50:

FINE REGULATOR:

Starting with the switch on position "1", slowly turn the fine regulator towardsthe right (from 0% to 100%). To find out the current being injected, the needleon the analogue ammeter is the guide at first and then the read out lp. on thedigital indicator.

SWITCHING SCALES:

If the nominal current is not reached, even with the regulator on 100%, it will

then be necessary to increase the switch regulation by one scale.

Adjustments are done by trial and error between the different regulationscales, starting with the lowest: 1 to 10 on the MPC-20 and from 1 to 8 on theMPC-50. Switching from one scale to another is always done off line, i.e.without turning the selector key and placing the regulator in the 0% position.

Voltage testing will be done AUTOMATICALLY at the same time asthe MPC-20 or MPC-50 are adjusted with the operating key. (The voltmeterbegins testing when the key is turned and blocks measurements when the keyis no longer turned.)


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READ TESTED VOLTAGE (V) on the display.

Note: If the read out on the display is less than 30 V the internal scale isautomatically changed to 30 V AC.

DISENGAGE THE OPERATION SELECTOR. Once the test hasfinished the values remain displayed until the key is turned again, theequipment is switched off or the Imax value is set again.

5.12.- TEST RESULTS (THAT WILL REMAIN DISPLAYED)

Real current Maximum current

of the test made

Im. NN,N I x. NNNNdefault theory

Voltage testedduring the test

Vm. NN,N V NNNNN Calculated voltagedefault theory

(step or touch)

Vm x IxSTEP VOLTAGE (Vp) : V = --------------------

Im

Vm x IxTOUCH VOLTAGE (Vc) : V = ---------------------

Im


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6.- TESTING GROUND RESISTANCE

The main advantage of testing ground resistance using high currents isthat as well as being measured, the ground is also being tested to see if it iscapable of accepting such a current. By doing it this way, one avoids errors of

measurement from low currents due to, for example, surface moisture or ahighly corroded cable or one with defective lining.

CONNECTION DIAGRAM

TESTED

VOLTAGE

TESTINGROD

TESTING GROUND RESISTANCE

GROUND TO

BE TESTED

AUXILIARY

GROUND

TEST INTENSITY lp


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6.3.- ATTACHING AND CONNECTING THE MPC-20 or MPC-50

The "OPERATING MODE" selector must be placed on Rt.

Attaching and connecting the MPC to the system is the same as that

for testing step and touch voltage.

Connecting the current circuit using the two output sockets is also thesame.

6.4.- ATTACHING THE MEASURING ROD

One of the voltmeter cables is connected to the ground to bemeasured.

The other voltmeter cable is connected to the GROUND using the"MEASURING ROD" in an area in between the ground to be measured and theauxiliary ground.

6.5.- TESTING VOLTAGES DUE TO ERRATIC CURRENTS

Prior to starting, press the "ERRATIC VOLTAGES" button (keeping itpressed down).

If the Vm value remains at 0 V the presence of erratic voltages andcurrents will be ruled out. If any value appears, it must be noted to besubsequently compared with the 20 A and 50 A measurements and theappropriate numerical corrections made).(See section 8 "CORRECTING READ OUTS").

6.6.- TESTING GROUND RESISTANCE

If testing has to be done at 20 A (MPC-20) or at 50 A (MPC-50),adjustments are made according to section 11.3.2.

If testing has to be done with currents below 20 A or 50 A respectively,the adjustment is also done by trial and error between the different regulationscales starting with the lowest (1, 2, 3, ...). Switching from one scale to anotheris always done off line, i.e. without turning the selector key (according tosection 11.3.2.).


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Measurements are taken automatically on turning the key (the

voltmeter and the ammeter begin testing on turning the key and blockmeasurements when the key is no longer turned).

BEFORE TURNING THE SELECTOR MAKE SURE THAT NO ONEIS USING THE POWER OR TESTING CIRCUIT.

READ TESTED VOLTAGE (V) on the display.

Note: If the read out on the display is less than 30 V the internal scale isautomatically changed to 30 V AC.

DISENGAGE THE OPERATION SELECTOR Once the test hasfinished the values remain displayed until the key is turned again, the

equipment is switched off or the equipment is disconnected.

The MPC-5 will automatically calculate resistance and store theresults.

6.7.- MEASUREMENT RESULTS (THAT WILL REMAIN DISPLAYED)

Real current

of the test made

Im. NN,N Rt :

Voltage testedduring the test

Vm. NN,N NNN.N Calculated groundresistance

Rt.= Vm./Im.

Ensure that the measuring electrode is actually testing the voltage drop inthe ground that is being tested which is a consequence of the current injectedby the MPC itself. Placing the measuring electrode in the right position is vital. Itis important that it is far from the area under the influence of both themeasuring electrode and the auxiliary electrode to obtain maximum accuracy.


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6.8.- REPEATING TESTS

Ensure that the measuring electrode is actually testing the voltage drop inthe ground that is being tested which is a consequence of the current injected

by the MPC itself. Placing the measuring electrode in the right position is vital. Itis important that it is far from the area under the influence of both themeasuring electrode and the auxiliary electrode to obtain maximum accuracy.

It is advised that the measuring rod is moved +10% and then -10% from itsstarting position along the axis formed by the earthing and the auxiliaryelectrode separated by a distance L (if its position L=20 metres, it is to bemoved 2 metres from its original position). Make a note of the resistance valuefor each position of the rod. If the values are the same or vary slightly themeasurement is correct. On the other hand if it is within the area influenced bythe two power slopes. The distance between the ground to be measured and

the auxiliary ground has to be increased.


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CHAPTER II

7.- EXISTING STANDARDS

7.3.- SUMMARY OF HIGH VOLTAGE REGULATIONS

The Technical Complementary instruction MIE-RAT-13 published in theB.O.E. (Official State Gazette) 183 of 1

stAugust 1984, section 1.1. sets the

maximum admissible step and touch voltages for EARTHINGINSTALLATIONS.

In sections 8.1 and 8.2 it establishes the requirement to verify that thestep and touch voltages are within the admissible limits. It establishes therequirement for periodical checking every 3 years as a maximum. It lays downthat the measuring electrodes that simulate feet must have a surface area of

200 square cm each and that they each have a downward force onto theground of 250 N.

STEP VOLTAGE-The voltage that can occur between the feet of somebody standing one

step away whilst the installation is operating" (I.E.C. standard 11-8, sec.176).

TOUCH VOLTAGE-The voltage that a human body may experience whilst in contact with

housings and metallic structures that normally do not carry voltages.

MAXIMUM ADMISSIBLE VOLTAGES- Maximum admissible step and touch voltages in a certain installation,

(B.O.E. 291 5-12-87), are determined by the following summarised formulae:

10 K KVp = -------------- Vc = -----------

t n t n

Being:

K=72 and n=1 for times less than 0.9 s.

K=78.5 and n=0.18 for times between 0.9 and 3 s.t = length of the fault in seconds.For times between 3 and 5 seconds the touch voltage will not exceed 64V and the step voltage 640 V.

For times above 5 seconds touch voltage will not exceed 50 V and stepvoltage 500 V.


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SUMMARY TABLE OF MAXIMUM VOLTAGES

TIME MAXIMUM STEPVOLTAGE

VOLTAGE TOUCHVOLTAGE

Over 5 s 500 V * 50 VFrom 3 to 5 s 640 V 64 V

2 s 690 V 69 V

1 s 785 V 78.5 V

0.9 s 800 V 80 V

0.7 s 1020 V 102 V

0.5 s 1440 V 144 V

0.2 s 3600 V 360 V

0.1 s or less 7200 V 720 V

* Supposes that the real step voltage on the human body is less than thatmeasured (shoes, etc.).

7.4.- STANDARDS REFERRING TO THE MPC-20 / MPC-50

MIE-RAT-01MIE-RAT-13MIE-RAT-19BOE 183 1

stAugust 1984

BOE 291 5thDecember 1987


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8.- CORRECTING THE READ OUTS

Results from testing touch or step voltages may be incorrect due to theexistence of erratic, vagabond or parasite currents passing through the ground.

The B.O.E. 291, of 5 of December of 1987 establishes:

1.1.12 "... unless a test method is used that eliminates the effect (in testing)of these parasite currents, e.g. polarity inversion, it will mean that the injectedcurrent will be 1% of the current set for the installation and will not be less than50 A for stations and substations and 5 A for transforming stations."

As a result of currents not indicated by the B.O.E. being used, it will benecessary to use phase inversion for testing.

It is also found that in practice, the tested erratic voltages are always

negligible in terms of those created by injected currents (as long as theyconform to the set minimum).

However, in certain cases it will be possible to do a pretest on existingvoltages without injecting a current. To do this tests by pressing "Erraticvoltages" are done. Only when measurements of erratic voltages are above10% of measurements with current injection, the following calculation must bemade:

Vp =( ) ( )

( )V V

Ve0 180

2

2 22+

Vp = Step or touch voltageVe = Voltage tested "ERRATIC VOLTAGES"V0 = Voltage tested "ON 0"V180 = Voltage tested "ON 180"


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DERIVATION OF THE FORMULA FOR STEP AND CONTACT VOLTAGE

The following equations are derived from the graph:

V Vp Ve Ve 12 2 2= + + ( sen ) ( cos )

Vp Ve Ve 22 2 2= + ( sen ) ( cos )

Developing the equations:

Vp Vp Ve Ve Ve 1 22 2 2 2 2 2= + + + sen sen cos Vp Vp Ve Ve Ve 2 22 2 2 2 2 2= + + sen sen cos

If the two equations are added, we have to:

V Vp Ve Vp Ve1 2 2 2 2 22 2 2 2 2 2 2 2

+ = + + = +(sen cos )

Solving Vp: Vp =( ) ( )

( )V V

Ve1 2

2

2 22+

V1 = read voltage on injecting current at 0V2 = read voltage on injecting current at 180Ve = read voltage without injecting current


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9.- MAINTENANCE

The MPC does not require specialised maintenance. As far as possibleavoid any adjustment, maintenance or repairs when the equipment is open. Ifthis is unavoidable it must be done by qualified personnel or technicians well

informed of the procedure to follow.

Before any modification to the connections, replacement, maintenance orrepair, the equipment must be disconnected from the supply.

If any operating fault or equipment protection fault is suspected, theequipment must be taken out of service ensuring that no accidentalreconnection may occur. The equipment is designed to have any of itscomponents replaced quickly in the event of breakdown.

10.- TECHNICAL SERVICE

In the event of any equipment failure or any operational queries pleasecontact the technical service of CIRCUTOR S.A.

CIRCUTOR S.A. - After sales servicec / Lepanto , 4908223 - TERRASSAtel - (+34) 93 - 745 29 00e-mail: [email protected]


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APPENDIX

MPC-50 INTERNAL TERMINAL BOARD

FUSIBLEMANIOBRA

400 V 230 V

CAMBIO DETENSIN

CHANGE OF VOLTAGE:

- Attach the voltage bridge in the required position- Attach the indicating tag on the external supply cable

OPERATING

FUSE

CHANGING

VOLTAGE

MPC-20 MPC-50 Indirect Earth Simulator Manual

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Transcript of MPC-20 MPC-50 Indirect Earth Simulator Manual