Recognization of AC 3 Phase Power Supply as Well as Supply Sequence

8/2/2019 Recognization of AC 3 Phase Power Supply as Well as Supply Sequence

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Date : 13 / 02 /2008.

T e c h n o S q u a r e(Industrial Automation & Engineering Lab Solutions)Cell: 9848565892, 9491378448.

E-mail:[email protected] & Res: H. No.1-1-61,Srinivasapuram Colony,

Old Paloncha-507115,Khammam district, Andhra Pradesh.

This is to certify that B. Tech Final year Students of Electrical and

Electronics Engineering, Vignana Bharathi Institute of Engineering and Technology ,

Ghatkesar, Aushapur, have done their Main project on a detailed study ofRecognitionof AC 3 phase power supply as well as supply sequence through the Technical

assistance of M/s. Techno Square Paloncha 507115, Khammam District, Andhra

Pradesh during the academic year of 2012. In this regard participated Students are asfollowing :

S.NO. Name of the Student Roll No

Smt. D. MANI, M.S. NARAYANA,

Directior. C.E.O.


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ABSTRACT

Topic :Reorganization of AC 3- Power Supply as well as Supply Sequence

using Active and passive network module.

The main aim of this project determines for the reorganization of AC 3-,

50Hz, 415V, 5 wired Power supply with corresponding neutral and earth as well

as supply sequence at the consumer incoming panel Bus.

In every Industry can be associated with different types of rotating

machines like AC / DC drives and other Industrial Control equipment. The AC 3-

I.M. can be run with the availability AC 3- power supply. In every Industrial

Sector before going to start the motor / machine by the operator first of all

observes weather the 3- power supply is there or not the power supply

recognized by the power indicators of the front panel display during the operators

inspection / observation for the status of power supply found that confirms OK

then only operator start the machine. In every Industrial sector giving priority to

the production as well as equipment to keep up the production every body

protection and safety of the work mens is much important thats why everybody

always must be maintain minimum safety precautions during works on the

machine. If the power indicators are not provided for the incoming supply and the

sequence also not OK as RYB which caused the motors gets may damaged

because of the operator does not knows weather and the process of production

may be reversed due to incorrect supply sequence.


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ACKNOWLEDGEMENT

The development of the project though it was an arduous task, it

has been made by the help of many people. We are pleased to express our thanks

to the people whose suggestions, comments, criticisms greatly encouraged us in

the betterment of the project.

This is an Acknowledgement of the intensive drive and success of my

Project. I am obliged and grateful to our project guide Sri. __________________

sir of EEE department of _________________ engineering college, Paloncha for

his valuable suggestions, sagacious guidance in all respects during the project of

my training.

First and far most we wish to take this opportunity to express

our sincere thanks to the H.O.D of EEE Department, _____________

ENGINEERING COLLEGE for the interest, technical support and suggestions

during the project leading us to success.

I would like to present my heart full thanks to Sri. M.S.Narayana the

C.E.O. of Techno square (Industrial R & D Center) for granting me permission for

the practical training, Project development and technical assistance with M/s.

Techno Square, Paloncha.

I would like to say thanks to our teammates for their great cooperation

and help during the project work.

________________________.


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INTRODUCTIO

N

TO

RECOGNIZATI

ON OF AC 3

POWER


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SUPPLY AS

WELL AS

SUPPLYSEQUENCE

INTRODUCTION

The main aim of this project determines for the reorganization of AC 3-,

50Hz, 415V, 5 wired Power supply with corresponding neutral and earth as well

as supply sequence at the consumer incoming panel Bus.

In every Industry can be associated with different types of rotating

machines like AC / DC drives and other Industrial Control equipment. The AC 3-

I.M. can be run with the availability AC 3- power supply. In every Industrial

Sector before going to start the motor / machine by the operator first of all

observes weather the 3- power supply is there or not the power supply

recognized by the power indicators of the front panel display during the operators


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inspection / observation for the status of power supply found that confirms OK

then only operator start the machine.

OPERATING PROCEDURE

THE ac 415V, 50Hz 5 wire supply taken from consumer panel and

connected to the TC 1. The output of TC 1 given to TC 2 via RYB indication

lamps with respect neutral and the same way RYB connected to the 3 pole Isolator

and the output of isolator given to the step down transformer of AC 415v, 12v.

These 12v connected to the bridge rectifier and its output given to the 3

network module and these 3 sequence reorganization relay gets energized

when 3 sequence if OK as RYB. Then only R 1 gets energized. Similarly

RYB phases if available at the input module then only the R 1 gets energized and

this supply promotes for getting on the load carrying relay. That means the AC


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415v 5 wire system with corresponding neutral & earth then only the RYB

indication will lit up on the front panel. In the same way if the phase sequence is

OK then R 4 will be lit ups. Accordingly we can recognize the power supply

system.

PROJECT ASSOCIATED INDUSTRIAL ACCESSORIES &

COMPONENTS

5.1 TERMINAL CONNECTORS


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The functions of connecters are to bring signal in and out of the equipment,

routing signal and power around between various parts of an instrument or

equipment and to provide flexibility by permitting circuit boards and larger

modules to be replaced. Connectors are available in a variety of sizes and shapes.

The defects present in connector are normally visible on inspection.

Common defects include loose fitting pins, missing guide pins, broken plastic in

connectors. A defective connector cannot be repaired and requires replacement.

Terminal connectors are used to inter connect different circuits, one part

with the other and the instruments to the instruments. Connectors are different


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types. They are, coaxial connectors, PCB mounted connectors and instrument

connectors.

5.2 PANEL / POWER INDICATORS


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For testing of any equipment and to show the status of circuit,

indicators are used. Neon lamp is a such type of indicator. This is a small glass

tube filled with neon gas. Two Electrodes produces a special type light. These are

used basically in high voltage and with a 100KE resistance. The function of

resistance to control the current. Some indicators are available with the resistance

which can be used in the mains supply line.

Small bulbs are also used as indicators and these are available

in different shapes, voltage and current rating in market. The rating of these also

in accordance with the current and voltage. These are mounted on the panel of

cabinet and covered with vase of plastic to brighten the light. These are available

in the rating of 6v and 12v and if 12v rating is used then the light of indicator


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goes down but age of bulb is increased. If by any reason voltage is increased then

these bulb not fused.

Nowadays LEDs are used frequently at the place of neon lamps and bulbs.

These have several benefits like small size, works on low voltage, rigid body and

available is different color. 1K resistance is connected is series with these to

control the like neon lamp. Small LEDs improves the look panel of equipment

and also protected them. Different types of indicators shown in figure below.

5.3 PROTECTIVE FUSES


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. A fuse is a small piece of wire connected in between two terminals

mounted on insulated base and is connected in series with the circuit.

The fuse perhaps the cheapest and simplest form of protection and is used for

protecting low voltage equipments against overloads and /or short circuits.

The fuse is very important device in any electrical circuit in which high

currents are needed. The high currents cant flow through the fuse beyond its

raging or capacity. If any currents flow through it the wire used in the fuse may

cut off. So the fuses are widely used in electrical systems to protect the system

from high voltages & high currents.

The fuse is expected to carry the normal working current safely without

overheating and during overloads or short circuits it gets heated up to melting

point rapidly. The materials used normally are tin, lead, silver, zinc, aluminum,

copper etc., For small values of currents an alloy of lead and tin in the ration of 37

percent and 63 percent respectively is used. For currents more than 15 amps this

alloy is not used as the diameter of the wire will be large and after fusing, the

metal released will be excessive. Silver is found to be quite satisfactory as a fuse

material because it is not subjected to oxidation and its oxide is unstable. The only

drawback is that it is a relatively costlier material. Therefore, for low range current

circuits either lead-tin alloy or copper is used.

DEF: It breaks the circit by fusing the fuse element when the current clowing

in the wire exceeds a certain predetermined value.


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FUSE WIRE: It is part of the fuse which melts when the current flowing in the

circuit exceeds a certain predetermined value and thus break the circuit.

MINIMUM FUSING CURRENT: It is the minimum current at which the fuse

element will melt.

FUSING FACTOR: It is the ratio of minimum fusing current to the rated

current.

Fusing Factor=(minimum fusing current)/(rated current).

The factor is always more than unity.

PROSPECTIVE CURRENT

a bo

Ip

Ic

Ip=perspective currentIc=cut-off current

Fault occured

Pre-arcing time Arcing time(Tpa) (Ta)

Total operating time=Tpa +Ta


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Ip shown dotted is the current which would have flown in the circuit if the

fuse had been absent. It is measured in terms of RMS value of ac component of

the fault current.

RUPTURING CAPACITY(OR BREAKING CAPACITY)

It is the MVA rating of the fuse corresponding to the largest perspective

current which the fuse is capable of breaking (rupturing) at the system voltage.

METAL MELTING

POINT(0C)

SPECIFIC

RESISTANCE

(MICRO OHM-CM)

Tin 230 11.2

Lead 328 21.5

Zinc 419 6.1

Aluminiun 670 2.85

Silver 960 1.64

Copper 1090 1.72

FUSE

REWIRABLE TYPE(SEMI CLOSED)

CARTRIDGE FUSE(COMPLETELY CLOSED)


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5.3.1 REWIRABLE FUSE LIMITATIONS

1. Unreliable operation, since the fuse wire is exposed to

atmosphere, ot gets oxidized and deteriorated, resulting in reduction of wore

section with passage of time. This increases the resistance causing operation of the

fuse at lower currents.

2. Local heating caused by loose connections.

3. Lack of discrimination.

4. Small time lag.

5.3.2 CARTRIDGE FUSE LIMITATIONS

1. It requires replacement of each operation .

2. It produces overheating of the adjacent contacts.

ADVANTAGES:

1. Capability of clearing high values of fault current.

2. Fault operation.

3. Non deterioration for long periods.

4. No maintenance needed.

5. Reliable discrimination.

6. Consistent in performance.

7. Cheaper than the other interrupting devices.


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8. Current limitation by cutoff action.

9. Inverse time-current characteristics.

5.3.3 APPLICATIONS

1. Protection of low voltage distribution system against over loads and short

circuits.

2. Protection of cables.

3. Protection of motors.

4. Protection of semiconductor devices.

5. Protection of busbars.

6. Back up protection to circuit breakers.

In many electronic equipments glass cartridge fuses are used. These are

of different capacity which may be form 10mA to several amperes.

To hold these fuses ready made fuse holders are available and the glass

fuse in placed inside this fuse holder. These fuses are also of two types. One type

of fuse blown immediately on flow of current excess then their rating. Another

type of fuse is called slow blow fuse. It caN bear excess current upto sometime

but if current pressure continuous then it goes blown. These type of fuses are used

with electric motor. Initially motor takes more current but when it comes in

speed then consumption of current goes less.

5.4 METERS


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Meters are used for measurement of voltage, these are of two types.

A. Moving Coil.

B. Moving iron.

A. MOVING COIL:

Moving Coil are costlier but needs very less current for operation. Inside

this Meter a coil of thin insulated. copper wire is mounted on axles between the

poles of an U type magnet. This coil is wounded on any lighter metal base. On

these axles jewel bearing are mounted on which the coil moves with low friction.

To maintain uniform magnetic field a cylindrical aluminum piece is connected

between the coil. When the current flows in any coil placed in magnetic field then

a magnetic field has also been produced by coil. When the magnetic field of

magnet and coil reacts with each other then a force is generated and acts on the

coil by virtue of which coil starts moving and also the pointer connected with

coil moves on the marked dial which is divided is equally intervals.


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B. MOVING IRON:

These meters are used frequently in all type of stabilizers due to their low

cost. The dial scale of these meters is divided into small intervals.

These meters consume more current with respect to moving coil meters and

pointer of this meter takes some times in stabilizing at its destination point.

A high wattage series resistance is used with meter and since it heats up so

its used out side the meter. This resistance heats up due to flow of excess current.

The scale of this meter is non linear means the length of intervals is not equal.

The main problem with these meters is due to improper damping the pointer

taken some time in stabilizing.

5.5 PROTECTIVE RELAYS


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The capital involved in a power system for the generation, transmission and

distribution of electrical power is so great that proper precautions must be taken to

ensure that the equipment not only operates as nearly as possible to peak

efficiencies, but also that it is protected from accidents.

The purpose of protective relays and protective relaying systems is to operate the

correct circuit breakers so as to disconnect only the faulty equipment from the

system as quickly as possible, thus minimizing the trouble and damage caused by

faults when they do occur.

The modern power system is very complex and even though protective

equipments from 4 to 5 % of the total cost involved in the system, they play a very

important role in the system design for good quality of reliable supply.

The most severe electrical failures in the power systems are shunt faults which are

characterized by increase in system current, reduction in voltage, power factor and

frequency. This protective relays do not eliminate the possibility of faults on the

system, rather their action starts only after the fault has occurred on the system. It


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would be ideal if protection could anticipate and prevent faults but this is

impossible except where the original cause of fault creates some effects which can

operate a protective relay.

There are two groups of relaying equipments for protecting any equipment:-

1. primary relaying equipment ,

2. back-up relaying equipment.

Primary relaying is the first line of defense for protection the equipments where as

the back up relaying works only when the primary relaying equipment fails which

means back-up relayong is inherently slow in action. Primary relaying may fail

because of failure of any of the following:

(i) protective relays (moving mechanism etc.),

(ii) circuit breaker ,

(iii) D.C tripping voltage supply,

(iv) Current or voltage supplies to the relays.

Since it is required that back up relays should operate incase primary relays fail,

the back-up relays should not have any thing common woth primary relays.

Hitherto, the practice has been to locate the back up relays at the different station.


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A second job of the back-up relays is to act as primary protection in case the

primary protection equipment is taken out for repair and maintenance.

SOME DEFINITIONS

RELAY: A relay is an automatic device which senses an abnormal

condition in an electric circuit and closed its contacts. These contacts in turn close

the circuit breaker trip coil circuit, thereby it opens the circuit breaker and the

faulty part of the electric circuit is disconnected from the rest of the healthy circuit.

PICK UP LEVEL: The value of the actuating quantity( current or voltage)

which is on the threshold above which the relay operates.


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RESET LEVEL: The value of current or voltage below which a relay

opens its contacts and comes to original position.

OPERATING TIME: The time which elapsed between the instant hen the

actuating quantity exceeds the pick up value to the instant when the relay contacts

close.

RESET TIME: The time which elapses between the instant when the

actuating quantity becomes less than the reset value to the instant when the relay

contact returns to its normal position.

PRIMARY RELAYS: The relays which are connected directly in the circuit to be

protected.

SECONDARY RELAYS: The relays which are connected in the circuit to

be protected through current and potential transformes.

AUXIALLARY RELAYS: Relays which operate in response to the opening

or closing of its operating circuit to assist another relay in the performance of its

function. This relay may be instantaneous or may have a time delay.


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REACH: A distance relay operates whenever the impedance seen by the

relay os less than the prespecified value. This impedance ot the corresponding

distance is known as the reach of the relay.

UNDER REACH: The tendency of the relay to restrain at the set value of

the impedance or impedance lower than the set value is known as underreach.

OVER REACH: The tendency of the relay to operate at impedances larger

than its setting is known as overreach.

Functional characteristics of protective relay

A protective relay is required to satisfy four basic functional characteristics:

(1) reliability, (2) selectivity, (3) speed and (4) sensitivity.

RELIABILITY:

The relay should be reliable is a basic requirement.It must operate when it is

required. There are various components which go in to ooperation before a relay

operates. Therefore, every component and circuit which is incolved in the

operation of the relay plays an important role; for example lack of suitable current

and voltage transformers may result in unreliable operation.


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Since the protective relays remain idle most of the time on the power syste,

proper maintenance will play a vital role in improving the reliable operation of the

relay. Inherent reliability is a matter of design based on long experience. This can

be achieved partly by:

(1) Simplicity and robustness in construction,

(2) High contact pressure,

(3) Dust free enclosures,

(4) Good contact material,

(5) Good work man ship and

(6) Careful maintenance.

SELECTIVITY:

It is the basic requirement of the relay in which it should be possible to select

which part of the system si faulty and which is not and should isolate the faulty

part of the system from healthy one. Selectivity is achieved in two ways:

(1) unit system of protection and

(2) non- unit system of protection.

SPEED:


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A protective relay must operate at the required speed. It should neither be too slow

which may result in damage to the equipment, nor should it be too fast which may

result in undesired operation during transient faults.

The shorter the time for which a fault os allowed to persist on the system,

the moe load can be transferred between given points on the power system with

out loss of synchronism. It can be seen that the severest fault os the 3-phase fault

and the least severe is the L-G fault in terms of transmission of power.

SENSITIVITY:

A relay should be sufficiently sensitive so that it operates reliably when required

under the actual conditions in the system which produce the least tendency for

operation. It is normally expressed in terns of minimum volt- amperes required for

the relay operation.

OPERATING PRINCIPLES OF RELAYS:

Basically there are two different operating principles of relays:


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(1) electromagnetic attraction and

(2) electromagnetic induction.

In the electromagnetic attraction type of relays the operation is obtained by

virtue of an armature being attracted to the poles of an electromagnet or a

plunger being drawn into a solenoid. These relays can be operated by both

d.c as well as a.c quantities. With d.c the torque developed is constant and

if this force exceeds a predetermined value the relay operates.

In case of a.c quantity the force is given by F I^2

F=KI^2

Let I=Im Sin wt; then

F=KIm^2-K Cos 2wt

This shows that the force consists of two components, one the constant,

independent of time, where as the other is a function of time pulsates at

double the supply frequency. The total deflecting force, therefore, pulsates

at double the frequency. Since the restraining force is constant the net force

is a pulsating one which means that the relay armature vibrates at double

the power supply frequency. These vibrations will lead to sparking between

the contacts and the relay will soon be damaged.


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To overcome this difficulty in a.c electromagnet, the two fluxes producing

the force are displaced in time phase so that the resultant deflecting force is

always positive and constant. This phase displacement can be achieved

either by providing two windings on the electromagnet having a phase

shifting network or by putting shading ring or coil method is more simple

and is widely used.

INDUCTION RELAYS:

The induction relays operate based on the electromagnetic induction

principle. Therefore, these relays can be used only on a.c circuits and not on

d.c circuits. Depending upon the type of rotor being used, these relays are

categorized as (1) induction disc type and induction cup type of relays.

In case of induction disc type of relays, disc is the moving element

on which the moving contact of relay is fixed with the cup. There are two

structures available under the induction disc type of relay:

(1) the shaded pole structure and

(2) the watthour meter structure.

DISTANCE RELAYS:

We will study a very interesting and versatile family of relays known as

distance relays with the help of universal torque equation. Under this only a few

types of relays will consider here. They are:


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(i) Impedance relays

(ii) Reactance relays

(iii) Mho relays.

It is to be noted that in electrical engineering impedance term can be

applied to resistance alone or reactance alone or a combination of both. In

protective relaying , however, these terms have different meanings and hence

relays under these names will have different characterstics.

From the universal torque equation putting K3 =0 and giving negative sign

to voltage term, it becomes

T=K1I^2-K2V^2 (neglecting spring torque)

This means the operating torque is produced by the current coil and

restraining torque by the voltage coil, which means that an impedance relay is a

voltage restrained over-current relay.

For the operation of the relay the operating torque should be greater than

the restraining torque, i.e.

K1I^2 > K2V^2

Here V and I are the voltage and current quantities fed to the relay.

Therefore,(v^2/I^2)


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or Z< Sqrt (K1/K2)

or Z< constant(design impedance).

This means that the impedance relay will operate only if the impedance

seen by the relay is less than a prespecified value( design impedance).

At threshold condition,

Z= Sqrt (K1/K2)

The operating characteristics of an impedance relay on V-I diagram is

shown in the figure...........14.13

The initial bend to the characteristic is due to the presence of spring torque.

Normally, the operating characteristics of distance relays are shown on an

impedance diagram or R-X diagram. This characteristic for an impedance

diagram is shown in fig 14.14

The impedance relays normally used as high speed relays. These relays

may use a balance beam structure or an induction cup structure. The

directional property to the impedance relay can be given by using simple

over current relay to work as a directional over current relay. This means


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the impedance unit will operate only when the directional unit has operated.

The characteristic of such a combination will be as shown in the fig 14.15

From the characteristic, it is clear that it the impedance vector as seen by

the relay lies in a zone indicated by the thick line ( intersection of st.line

and circle ) the relay will operate, otherwise, it will not.

REACTANCE RELAY:

In this relay the operating torque is obtained by current and the

restraining torque due to a current voltage directional element. This

means, a reactance relay is an over current relay with directional restraint.

The directional element is so designed that its maximum torque angle is

90, i.e. T=90 in the universal torque equation.

T=K1I^2-K3VI cos(- T) = K1I^2-K3VI cos(-90)

= K1I^2-K3VI sin

For the operation of the relay,

K1I^2 > K3VI sin

((VI)/I^2) sin < (K1/K3)


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Or Z sin < (K1/K3)

X < (K1/K3)

This means for the operation of the relay the reactance seen by the relay

should be smaller than the reactance for which the relay ha beec designed.

The characteristic will be as shown in fig 14.16

This means if the impedance vector head lies on the parallel lines

( R- axis and the operating characteristic) this will have a constant X

component. The important point about this characteristic is that the resistant

component of the impedance has no effect on the operation of the relay. It

responds only to the reactance component of the impedance. The relay

will operate for all impedances whose heads lie below the operating

characteristic whether below or above the R-axis.

This relay as can be seen from the characteristic, is a non directional relay.

This will not be able to discriminate when used on transmission lines, whether the

fault has taken place in the section where the relay is located or it has taken place

in the adjoining section. It is not possible to use a directional unit of the type used

along with impedance relay because in that case the relay will operate even under

normal load conditions if the system is operating at or near unity power factor

condition. Under the condition of high power factor or leading power factor, the

impedance seen by the relay is a very low or even negative resistance. The relay


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that is used to give directional feature to the resistance relay, is known as MHO

relay or ADMITTANCE relay.

MHO RELAY:

In this relay the operating torque is obtained by the V-I element and

restraining torque due to the voltage element. This means a mho relay is a voltage

restrained directional relay.

From the universal torque equation,

T = K3VI cos(- T)-K2V^2

For the relay to operate

K3VI cos(- T) >K2V^2

Or (v^2/(VI)) < ( K3/K2) cos(- T )

Or Z < ( K3/K2) cos(- T )

This characteristic, when drawn on an admittance diagram is a straight line pssing

through the origin and if drawn on an impedance diagram it is a circle passing

through the origin as shown in the figure 14.18.


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The relay operates when the impedance seen by the relay forms within this

circle. The relay is inherently directional so that it needs only one pair of contacts

which makes it fast tripping for fault clearance and reduces the VA burden on the

current transformers.

5.6 SWITCHES

A switch is used to make or break the electric circuit. It should so operate

that it must make the circuit firm. At the instant of breaking the switch it should

break the current so there is no formation of arc between the switch blades and

contact terminals. Formation of arc burns or damages the switch contacts. Such an

arc is avoided usually by means of providing a spring to movable blade so as to

have a quick action.

Manual switches are operated by hand. Normally these switches are used in

houses for switching ON and OFF the equipments. Generally it can bear the

current more than 5 AMP. There are so many types like-

1. Piano Type

2. Toggle Type

3. Rocker Type

4. Rotary Type


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5.6.1 Toggle type

This is lever type switch which is mounted mostly on panel. This is used in

both electrical and electronic equipments. Toggle switch is also used like

piano switch mostly it is used for selection from once circuit from one

circuit from the two. These are of following types.

A. Single Pole Single Throw

B. Single Pole double Throw

C. Double Pole single Throw

D. Double pole double Throw


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A. Single Pole Single Throw :-

This is used like general ON/OFF switch. It has two pins and construction

of this is shown below.

B. Single Pole Double Throw :-

In this lever works in two positions. Both the positions are shown in figure,

in first position switch makes contact of S 1 and in second position it makes

contact of switch S 2.

C. Double Pole Single Throw :-

In this toggle switch lever makes to contacts in one position in other

position both contacts get opened. Both position are shown in the figure.

D. Double Pole Double Throw :-

In this toggle switch the lever makes two contacts in each position. These

contacts are made in such a manner that contacts of first position opened in

second position as shown in figure. Inside the switch two contacts are in

make position and two are in break position. By changing the lever contact

position changed means contact go to break and break contact go to make.


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CONCLUSION

In every Industrial sector giving priority to the production as well as

equipment protection also must important to keep up the production, every bodys

protection and safety of the work mens is much important thats why everybodyalways must be maintain minimum safety precautions during works on the

machine. If the power indicators are not provided for the incoming supply and the

sequence also not OK as RYB which caused the motors gets may damaged

because of the operator does not knows weather and the process of production

may be reversed due to incorrect supply sequence. Accordingly we finally

concluded that the above said facts are true. Hence this project Ckt implementation

100% necessary at every Industry.


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Recognization of AC 3 Phase Power Supply as Well as Supply Sequence

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Transcript of Recognization of AC 3 Phase Power Supply as Well as Supply Sequence