DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING LAB.pdf · DEPARTMENT OF ELECTRICAL AND...

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

Name of the Faculty: Mrs. D.DIVYA Class: B.Tech III EEE-II SEM

Course Name: : POWER SYSTEMS LAB Course Code: EE604PC

Academic Year: 2018-19

Course objectives

1 To Perform testing of CT, PT’s and String Insulators

2 To find sequence impedances of 3-phase synchronous machine and Transformer

3 To perform fault analysis on transmission line models and generators.

Course outcomes

Course

Outcome Course Outcome Statement Bloom’s

Taxonomylevel

C324.1 Students will able to perform various load flow techniques. Synthesis

C324.2 Students will Understand different protection models comprehension

Application

C324.3 Students will Analyze the functional operation of IDMT over current relay,

Micro-processor based over voltage/under voltage relay. Analysis

C324.4 Students will know about the formation of Zbus and Ybus. comprehension

Application

C324.5 Students will analyze the sequence impedances of transformer and

generators. Analysis

C324.6 Students will able to Analyze the performance of transmission line model. Analysis

Faculty Signature

Name of the Faculty: Mrs. D.DIVYA Class: B.Tech III EEE-II SEM

Course Name: : POWER SYSTEMS LAB Course Code: EE604PC

Academic Year: 2018-19

CO-PO MAPPING

PO 1

PO

2

PO 3

PO

4

PO 5

PO

6

PO 7

PO

8

PO 9

PO

10

PO 11

PO

12

PSO1 PSO2 PSO3

C421.1 2 3 2 1 2

C421.2 1 3 2 2

C421.3 3 2 2 2

C421.4 2 1 2 2

C421.5 2 2

C421.6 3 2

AVG 1.75 2.8 1.5 1.66 2 2 2

Exp. No:

Date:

CHARACTERISTICS OF IDMT OVER CURRENT RELAY

AIM: To plot characteristics of inverse definite minimum time over current relay.

APPARATUS:

S. No. Name of the Equipment Range Type Quantity

.1 IDMT Over current relay

kit -

-

01

2. Connecting wires

As required

BLOCK DIAGRAM:

Wiring Sequence:

PROCEDURE:

1) Make the wiring sequence as per wiring schedule. Keep the dimmer at minimum position.

2) Ensure that 'Bypass switch' on EMT-39 Panel is at 'OFF' position i.e. RH5 side.

3) Set the pickup value of the current (Relay current setting) marked at 2.5A by inserting the

plug in the groove of IDMT over current relay.

4) Now set Time multiplier setting (TMS) = 1 by moving thumb wheel provided on the

control shaft to point marked at 1.0 initially.

5) Now switch on AC supply to EMT16A & EMT39. Press start push button PB1 on EMT39

to switch ON the protection circuit & contactor,

6) Now slowly increased the dimmer setting by observing current on EMT39 to set 2.5A first.

At this current the relay will not trip.

7) Now again increase the dimmer setting to set relay current of 5A. If the relay trips before

setting, again make it ON and set the current to 5A. Now press stop button, reset the timer on

EMT39 by pressing reset key provided on timer.

8) Now again press start push button & note down the time required to trip protection relay

using timer for 5A relay current Et note down above reading in observation table.

9) Now take various readings for different current passing through protection relay as per

observation table.

10) Now repeat the above procedure for TMS = 0.5 & fill observation table.

11) Calculate PSM value using formula.

12)Now plot the graph of PSM on X-Axis verus operating time in seconds on Y-Axis for

TMS=1 &TMS=0.5

TABULAR COLUMN:

S.NO Currentthrough

relay=Ir(On

EMT39)

PSM=Ir/X RelayOperating

time in seconds for

TMS=1(On

EMT39)

Relay Operating time

in seconds for

TMS=0.5(onEMT39)

X=2.5 X=5

X=2.5 X=5 X=2.5 X=5

MODEL GRAPH:

PRECAUTIONS:

1) Avoid loose connections and parallax errors.

CONCLUSION:

RESULT:

Exp. No:

Date :

DIFFERENTIAL PROTECTION OF SINGLE PHASE

TRANSFORMER

AIM: To study the differential protection scheme for a single phase transformer

APPARATUS:

Sl.No Apparatus Type Quantity

01 1-Phase Transformer 230V/50V,

(500VA)

Shell type 01 No

02 1-Phase Variac (0-250V, 6Amps) Closed type 01 No

03 Ammeters (0-30 amps) Digital 04 No’s

04 Differential relay Micro Processor type. 01 No

05 Connecting wires --- As required

THEORY:

A Differential relay responds to vector difference between two or more similar

electrical quantities. From this definition the Differential relay has at least two actuating

quantities say 1-1 and 2-1. The two or more actuating quantities should be same.

Ex: Current/Current.

The Relay responds to vector difference between 1-1 &2-1 which includes magnitude

and /or phase angle difference. Differential protection is generally unit protection. The

protection zone is exactly determined by location of CTs. The vector difference is actuated by

suitable connection of CTs or PTs secondary’s. Most differential relays are current

differential relays in which vector difference between current entering the winding & current

leaving the winding is used for relay operation. Differential protection is used for protection

of Generators, Transformers etc. Internal fault is created using switch and relay operation

observed for various TSMs. Relay operations for external faults can also be studied.

CIRCUIT DIAGRAM:

PROCEDURE:

1. Make the connections as shown in fig.

2. Apply rated voltage 230V to primary by varying the Variac.

3. By applying load observe various meter readings.

4. Now switch ON the Fault switch so as to create an internal fault.

5. Note down the various meter readings when relay operates.

6. Note down the Relay Trip condition.

7. Reset the relay after it gets tripped.

TABULAR COLUMN:

S.No Primary Voltage Primary

current

Secondary

Voltage

Secondary

current

Fault

Current

Relay

condition

PRECAUTIONS:

1. Avoid loose connections

2. While removing connecting wires be careful .

RESULTS:

Exp No:

Date:

CHARACTERSTICS OF MICROPROCESSOR BASED OV/UV

RELAY

AIM: To perform experiment on under/Over voltage protection

APPARATUS:

S. No. Name of the Equipment Range Type Quantity

.1 IDMT Over current relay

kit -

-

01

2. Connecting wires

As required

BLOCK DIAGRAM:

WIRING SEQUENCE:

PROCEDURE:

1) Make the wiring sequence as per wiring schedule. Keep the dimmer at minimum position.

Keep the FW-OFF-REV switch on EMT4A at OFF position.

2) Ensure that 'Bypass switch' on EMT-39 Panel is at 'OH' position i.e. LHS side.

3) Relay setting: Now switch ON the auxiliary power supply for relay by making ON 4A

MCB at EMT1. The numeric over/under voltage relay we are using is a three phase relay

indicating three phases as R, Y and B. Press menu key you will get two options i.e.

PARAMETER SETG & TRIP TEST. Select PARAMETER SETG using up/down arrows

keys and press enter key, you will get RATED VOL. SET AT 230V, press enter. Now set the

rated voltage to 230V using up/down and left/right arrow keys and press enter. Now you will

get UV SET AT 210V ACTV INH. Now select ACTV using left/right arrow keys a press

enter. Now set the required under voltage to 210V and press enter. Now you will get UV

DLAY SET AT 005 secs, press enter and set it to 005 secs, press enter. You wilt get OV SET

AT 255V ACTV->INH, select ACTV using left right arrow keys, and press enter. Now set

required over voltage to 255V and press enter. You will get OV DLAY SET AT 005secs, set

it to 005 sec and press enter. Now you will get UBV SET AT ACTV -> INH, select INH and

press enter, now unbalanced is inhibited massage is displayed. Now you will get PH. REV.

PROT ACTV—*INH, select ACTV Et press enter. To come out of this mode press reset key.

4) Now Press start push button PB1 on EMT39 to switch ON the protection circuit Et

contactor. Press start push button on EMT1 panel to make 3 phase supply ON.

5) Now slowly increase the dimmer by observing alt three phase voltages per phase on

EMT34 and set it to 230VAC per phase.

6) Now keep the FWD-OFF-REV switch on EMT4A at FWD position. Press reset button on

(y relay. Observe relay display so that there should not be any fault. The relay display "itt

show R, Y ,B voltages. If the relay is showing reverse phase fault, then interchange R & Y

phase from mains or move the switch on EMT4A at REV position and reset the relay. Here as

the R phase of relay is directly connected from mains supply without any dimmer, the relay

display will show R phase constant and Y and B will vary as per dimmer set.

7) Put bypass switch on EMT39 panel at 'OFF' position i.e. on RHS side.

8) Now to create over voltage fault, slowly increase the dimmer observing OV LED on relay

panel so that it will just glow. After delay time as set in the relay, the relay will give trip

signal to EMT1 and EMT1 DOL starter will shut off & 3 phase supply will cut-off.

9) Now take the readings as per observation table1 for over voltage protection.

10) To remove the above fault, keep bypass switch on EMT39 at ON position i.e. on LHS

side. Press start button on EMT39 first and then on EMT1. Set the voltages to 230V by using

dimmer, reset the relay Et again put the switch on EMT39 to OFF position i.e. on RHS side.

11)Now take another set of reading for OV set of 250V et repeat step 3 to 9.

12) Now to create under voltage fault, slowly decrease the dimmer observing UV LED on

relay panel so that it will just glow. After delay time as set in the relay, the relay will give trip

signal to EMT1 and EMT1 DOL starter will shut off Et 3 phase supply will cut-off.

13) Now take the readings as per observation table 2 for under voltage protection.

14) To remove the above fault,keep bypass switch on EMT 39 at ON position i.e.on LHS

side.Press start button on EMT 39 first and then on EMT 1.set thevoltages to 230V by using

dimmer,reset the relay & again put the switch on EMT 39 to OFF position i.e.on RHS side

15) Now take another set of reading for UV set of 200 & repeat step 3 to 9 & 12-13.

OBSERVATIONS:

S.No OV Set in relay TRIP Voltages

R(V) Y(V) B(V)

1 255

2 250

Table1. For over voltage protection

S.No UV Set in relay TRIP Voltages

R(V) Y(V) B(V)

1 210

2 200

Table2. For under voltage protection

PRECAUTIONS:

1. Avoid loose connections.

CONCLUSION:

RESULT:

Exp. No:

Date:

TESTING OF CURRENT TRANSFORMER, POTENTIAL

TRANSFORMER and STRING INSULATOR

TESTING OF C.T. & P.T. :

AIM: To study the performance of current and potential Transformers.

APPARATUS:

Sl.No Apparatus Range Quantity

1. Ammeters (0 – 20) A 2

2. Voltmeters (0 – 500) V 2

3. Connecting Wires - -

4. C.T. s 20/5A C.T

10/5A C.T

1

1

5 P.T. s 400/100V P.T

200/100V P.T

1

1

THEORY:

1. Current transformers reduce high voltage currents to a much lower value and

provide a convenient way of safely monitoring the actual electrical current flowing in

an AC transmission line using a standard ammeter. The principal of operation of a

basic current transformer is slightly different from that of an ordinary voltage

transformer. Current transformers can reduce or “step-down” current levels from

thousands of amperes down to a standard output of a known ratio to either 5 Amps or

1 Amp for normal operation. Thus, small and accurate instruments and control

devices can be used with CT’s because they are insulated away from any high-voltage

power lines. There are a variety of metering applications and uses for current

transformers such as with Wattmeter’s, power factor meters, watt-hour meters,

protective relays, or as trip coils in magnetic circuit breakers, or MCB’s.

2. Potential transformer or voltage transformer gets used in electrical power systems

for stepping down the system voltage to a safe value which can be fed to low ratings

meters and relays. Commercially available relays and meters used for protection and

metering, are designed for low voltage. This is a simplest form of potential

transformer definition. Potential transformer theory is just like a theory of general

purpose step down transformer. Primary of this transformer is connected across the

phase and ground. Just like the transformer used for stepping down purpose, potential

transformer i.e. PT has lower turns winding at its secondary. The system voltage is

applied across the terminals of primary winding of that transformer, and then

proportionate secondary voltage appears across the secondary terminals of the PT.

The secondary voltage of the PT is generally 110 V. In an ideal potential transformer

or voltage transformer, when rated burden gets connected across the secondary; the

ratio of primary and secondary voltages of transformer is equal to the turns ratio and

furthermore, the two terminal voltages are in precise phase opposite to each other. But

in actual transformer, there must be an error in the voltage ratio as well as in the phase

angle between primary and secondary voltages.

CIRCUIT DIAGRAM:

A) Current transformer circuit

B) Potential transformer circuit

PROCEDURE:

For C.T. Circuit:

1. Give connections as per the circuit diagram.

2. Apply rated current to primary side of CT.

3. Note down ammeter readings.

4. Connect ammeter in secondary side of CT.

5. Note down the secondary ammeter readings.

6. Observe CT performance by doing above procedure.

For P.T. Circuit:

1. Give connections as per the circuit diagram.

2. Apply rated voltage to primary side of PT.

3. Note down voltmeter readings.

4. Connect voltmeter in secondary side of PT.

5. Note down the secondary voltmeter readings.

6. Observe PT performance by doing above procedure

TABULAR COLUMN:

For C.T. Circuit:

S.No C.T Range CT Primary(A) CT Secondary(A)

20/5A C.T

10/5A C.T

For P.T. Circuit:

S.No P.T Range PT Primary(V) PT Secondary(V)

400/100V P.T

200/100V P.T

PRECAUTIONS:

1. Avoid loose connections

2. While removing connecting wires be careful

RESULTS:

TESTING OF STRING INSULATOR:

AIM: To determine string efficiency of suspension insulator with and without guard ring.

APPARATUS:

S.NO. APPARATUS RATING QUANTITY

1. 1-Phase Auto transformer. 100Volt/1Amp 01

2. Digital Voltmeter. 300Volt 01

3. MCB Protection. 20A 01

4. Fuse Protection. 1A 01

5. Capacitors. 2 micro Farad 03



8. Connecting wires. --- As required

THEORY:

A string of suspension insulators consists of a number of porcelain discs connected in series

through metallic links. Fig. 1 (i) shows string of suspension insulators. The porcelain portion

of each disc is in between two metal links as shown in Fig. 1 (ii). Therefore, each disc forms

a capacitor C as shown in Fig. 1 (iii). This is known as mutual capacitance or self-

capacitance. However, in actual practice, capacitance also exists between metal fitting of

each disc and tower or earth. This is known as shunt capacitance C1. Due to shunt

capacitance, charging current is not the same through all the discs of the string [See Fig. 1

(iii)]. Therefore, voltage across each disc will be different. Obviously, the disc nearest to the

line conductor will have the maximum voltage. Thus referring to Fig. 1 (iii), V1 will be much

more than V2 or V3.

The following points may be noted regarding the potential distribution over string of

suspension insulators:

(i) The voltage impressed on a string of suspension insulators does not distribute itself

uniformly across the individual discs due to the presence of shunt capacitance.

(ii) The disc nearest to the conductor has maximum voltage across it. As we move towards

the Cross-arm, the voltage across each disc goes on decreasing.

(iii) The unit nearest to the conductor is under maximum electrical stress and is likely to be

punctured. Therefore, means must be provided to equalize the potential across each unit.

(iv) If the voltage impressed across the string were d.c, then voltage across each unit would

be the same. It is because insulator capacitances are ineffective for d.c.

STRING EFFICIENCY

The ratio of voltage across the whole string to the product of number of discs and the voltage

across the disc nearest to the conductor is known as string efficiency.

conductor nearest to disc across Voltage ×n

string theacross Voltage= efficiency String

Where n = number of discs in the string.

String efficiency is an important consideration since it decides the potential distribution along

the string. The greater the string efficiency, the more uniform is the voltage distribution. Thus

100%string efficiency is an ideal case for which the voltage across each disc will be exactly

the same. Although it is impossible to achieve 100% string efficiency, yet efforts should be

made to improve it as close to this value as possible.

METHODS OF IMPROVING STRING EFFICIENCY:

(I) BY USING LONGER CROSS-ARMS (II) BY GRADING THE INSULATORS. (III) BY USING A GUARD RING

CIRCUIT DIAGRAM:

1 Phase, 230V, 50 Hz,

AC Supply

MCB

1-Phase, 0 – 230 V

Variac

Fuse C1

C1

C1

C

C

C

C E1

E2

E3

E4

GS1

WITHOUT GUARD RING

S2

S3

S4

E

STRING

Fig 1: Without Guard Ring

1 Phase, 230V, 50 Hz,

AC Supply

MCB

1-Phase, 0 – 110 V

Variac

Fuse C1

C1

C1

C

C

C

C E1

E2

E3

E4

GS1

WITH GUARD RING

S2

S3

S4

C2

C2

C2

S7

S8

S9

S10

S11

S12

STRING

GUARD RING

Fig 2: With Guard Ring

PROCEDURE:

Without Guard Ring:

1. Connect the circuit as per the Fig. 1.From one of the Variac output terminals connect

to terminals S1 and other Variac output terminal to G as shown in Fig. 1.

2. Apply voltage from the Variac across the string in steps of 20V starting from 30V to

110V.

3. Measure the voltage across S1 and S2(which is to be noted as E1); S2 and S3(which is

to be noted as E2); S3 and S4(which is to be noted as E3) ; S4 to G( which is to be noted

as E4)

4. Tabulate the voltages E1 to E4 in the table 1.

5. Calculate the string efficiency without guard ring.

With Guard Ring:

1. Connect the circuit as per the Fig. 2.From one of the Variac output terminals connect

to terminals S1 and other Variac output terminal to G. To connect the guard ring to the

string, connect the terminals S4-S7, S3-S8, S2-S9 and also make connections between

S1-S10, S1-S11 and S1-S12

2. Apply voltage from the Variac across the string in steps of 20V starting from 30V to

110V.

3. Measure the voltage across S1 and S2(which is to be noted as E1); S2 and S3(which is

to be noted as E2); S3 and S4(which is to be noted as E3) ; S4 to G( which is to be noted

as E4)

4. Tabulate the voltages E1 to E4 in the table 2.

5. Calculate the string efficiency with guard ring..

TABULAR COLUMNS:

Without Guard Ring:

Table 1

E E1 E2 E3 E4 Efficiency

With Guard Ring:

Table 2

E E1 E2 E3 E4 Efficiency

CALCULATIONS:

conductorpowerthenearunittheacrossVoltagestringtheinunitsofnumber

stringtheacrossVoltageEffciencyString

RESULTS:

Exp. No: Date:

DETERMINATION OF SEQUENCE IMPEDANCES OF

THREE PHASE SYNCHRONOUS MACHINE

AIM: To determine the Positive, Negative and Zero sequence of impedances or sequence

impedances of the given three phase alternator.

APPARATUS:

S.No Apparatus Type Quantity

01. DC motor coupled to alternator set ----- 01 No.

02. Ammeters (0-2 amps DC) Digital 01 No.

03. Ammeters (0-20 amps DC) Digital 01 No.

04. Ammeters (0-5 amps AC) Digital 01 No.

05. Voltmeters (0-500 Volts, AC) Digital 01 No.

06. Rheostat 370 ohms/1.7 amps Tubular type 01 No.

07. Separate Excitation source(0-220V/2A DC) ----- 01 No.

08. Connecting wires ----- required

Theory:

The positive, negative and zero phase sequence components are called the symmetrical

components of the original unbalanced system. The term ‘symmetrical’ is appropriate

because the unbalanced3-phase system has been resolved into three sets of balanced (or

symmetrical) components.

(i) A balanced system of 3-phase currents having positive (or normal) phase sequence. These

are called positive phase sequence components.

(ii) A balanced system of 3-phase currents having the opposite or negative phase sequence.

These are called negative phase sequence components.

(iii) A system of three currents equal in magnitude and having zero phase displacement.

These

are called zero phase sequence components.

Synchronous generators. The positive, negative and zero sequence impedances of rotating

machines are generally different. The positive sequence impedance of a synchronous

generator is equal to the synchronous impedance of the machine. The negative sequence

impedance is much less than the positive sequence impedance. The zero sequence impedance

is a variable item and if its value is not given, it may be assumed to be equal to the positive

sequence impedance. It may be worthwhile to mention here that any impedance Zn in the

earth connection of a star connected system has the effect to introduce an impedance of

3Znper phase. It is because the three equal zero-sequence currents, being in phase, do not sum

to zero at the star point, but they flow back along the neutral earth connection. Experimental

set up to conduct OCC and SCC is made available. With the help of observations

Synchronous impedance can be calculated.

The –ve sequence impedance is much less than +ve Sequence impedance. The zero sequence

impedance is a variable item and if its value is not given, it may be assumed to be equal to

the +ve sequence impedance. For Zero sequence impedance a separate model is used to

conduct of experiment.

CIRCUIT DIAGRAMS:

(i) Determination of Positive Sequence Impedance Z1:

220V,DC Supply

Rectifier1 Phase,

230V, 50 Hz, AC Supply

A

V M

L F A

F

FF

A

AA

MCB 3-Point Starter

U1

U2

V1

V2

W1

W2

V

A

Z ZZ

0 – 200 V DC

Fuse Open Circuit Test Short Circuit Test

(ii) Determination of Negative Sequence Impedance Z2 :

(iii) Determination of Zero Sequence Impedance Z0 :

PROCEDURE:

(i) For Determination of Positive Sequence Impedance Z1:

In order to determine the positive sequence impedance, open circuit and short circuit tests are

to be performed.

Open Circuit:

1. Connect the circuit as shown in the circuit diagram.

2. Field rheostat of the motor should be kept in minimum position and single phase variac

should be in minimum output position.

3. Switch on the DC supply and start the motor-alternator set with the help of a three point

starter.

4. Adjust the field rheostat of the motor to set motor-alternator set to the rated speed.

5. Slowly vary the Variac to increase the field excitation of the synchronous machine. Note

down the value if If and V up to the rated voltage 415V.

6. Bring back the single phase Variac to the initial position, field rheostat to the minimum

resistance position and switch off the MCB.

Short Circuit Test:

1. Connect the circuit as shown in the circuit diagram.

2. Field rheostat of the motor should be kept in minimum position and single phase variac

should be in minimum output position.

3. Switch on the DC supply and start the motor-alternator set with the help of a three point

starter.

4. Adjust the field rheostat of the motor to set motor-alternator set to the rated speed.

5. Slowly vary the variac such that the rated current flows through the alternator. Note

down the field current and armature current.

6. Bring back the single phase variac to the initial position, field rheostat to the minimum

resistance position and switch off the MCB.

(ii) For Determination of Negative Sequence Impedance Z2 :

1. Connect the circuit as per the circuit diagram.

2. Keep the armature resistance of the motor at maximum resistance position, field rheostat

of the motor at minimum position and single phase variac at minimum output position.

3. Switch on MCB and start the motor-alternator set using 3 point starter.

4. Slowly apply the voltage and observe the fluctuations in voltmeter and ammeter of the

alternator.

5. Adjust the armature rheostat of the motor to get slow oscillations.

6. Note down the minimum and maximum values of voltage and current.

7. Bring back all the rheostats and variac to the initial positions and switch off the supply.

(iii) Determination of Zero Sequence Impedance Z0 :

1. Connect the circuit as per the circuit diagram.

2. The three phase windings of the synchronous machine are connected in series.

3. Apply low voltage to the armature so that rated current flows in the series winding.

4. Note down the value of voltmeter and ammeter.

5. Reduce the voltage and switch off the supply.

TABULAR COLUMNS:

(i) Positive Sequence Impedance Z1:

OC test

If

V

SC test

Isc

If

Plot OCC and SC characteristics and calculate the positive sequence impedance

𝒁𝟏 =𝑽𝑶𝑪

𝑰𝑺𝑪 Ω For the same filed current.

(ii) Negative Sequence Impedance Z2 :

𝒁𝟐 =𝑽

√𝟑 ∗ 𝑰 Ω

(iii) Zero Sequence Impedance Z0 :

V I 𝒁𝟎 =𝑽

𝟑×𝑰Ω

PRECAUTIONS:


2. Take the readings without any parallax error

RESULT:

Exp. No: Date:

DETERMINATION OF SEQUENCE IMPEDANCE OF THREE

PHASE TRANSFORMER

AIM: To find positive, negative and zero sequence impedances of the given three phase

winding transformer.

APPARATUS:

3-Phase auto Transformer 1 no

XPO-TT trainer kit 1 no

Patch Cards

Theory:

Before applying proper electrical protection system, it is necessary to have through

knowledge oft h e con di t io ns of elec t r ica l power s ys t em du r ing fau l t s . T he

kn owl ed g e of el ec t r ica l fault condition is required to deploy proper different

protective relays in different locations of elec t r ica l power sys t em, Informa t ion

r ega rding va lu es of max imu m and minimu m fault currents, voltages under those

faults in magnitude and phase relation with respect to the currents at differ ent par ts of

power system, to be gather ed for proper application of protection relay system in

those different parts of the electrical power system. Collecting the information f+rom

different parameters of the system is generally known as electrical fault calculation.If

fault current in any particular branch of the network is required, the same can be

calculated after combining the sequence components flowing in that branch. This

involves the distribution of sequence components currents as determined by

solving the above equat ions, in their respective network according to their relative

impedance. Voltages it any point of the network can also he determine once the

sequence component currents and sequence impedance of each branch are known.The

impedance offered by the system to the flow of positive sequence current is called positive

sequence impedance.Theimpedance offered by the system to the flow of negative sequence

current is called negative sequence impedance.The impedance offered by the system to

the flow of zero sequence current is known as zero sequence impedance. In previous

fault calculation, Z1,Z2 & Z0 ar e pos it ive, nega t iv e and zero sequ ence impedance

respectively

I) FOR Z12 MEASUREMENT:

BLOCK DIAGRAM:

WIRING SEQUENCE:

PROCEDURE:

1.Make the wiring as per wiring sequence.

2. Keep the dimmer knob at fully anticlockwise direction.

3. Make ON input supply using MCB on EMT1, put EMT34B in current mode. Now adjust

dimmer such that total of 0.5.A current flows through secondary windings of the transformer

observing. on EMT34B on current mode.

4) Now note down the readings of current, voltage & PF on EMT34A in following

observation table. Switch off the input supply after taking readings and keep dimmer at

minimum position.

TABULAR COLUMN:

S. No. Voltage

L-N(V)

Current

I(A)

Power

(W) Pf(CosØ) Z12=V/I

1. RN=

2. YN=

3. BN=

II) FOR Z23MEASUREMENT:

BLOCK DIAGRAM:

WIRING SEQUENCE:

PROCEDURE:

1 Make the wiring as per wiring sequence.

2 .Keep the dimmer knob at fully anticlockwise direction.

3. Make ON input supply using MCB on EMT 1, put EMT34B in current mode. Now adjust

dimmer such that total of 0.036A current flows through tertiary windings of the transformer

observing on EMT34B on current mode.

4. Now note down the readings of current. voltage & PF on EMT34A in following


minimum position.

TABULAR COLUMN:

S. No. Voltage

L-N(V)

Current

I(A)

Power


1. RN=

2. YN=

3. BN=

III) FOR Z13MEASUREMENT

BLOCK DIAGRAM:

WIRING SEQUENCE:

PROCEDURE:

1. Make the wiring as per wiring sequence.

2. Keep the dimmer knob at fully anticlockwise direction.

3. Make ON input supply using MCB on EMT 1, put EMT34B in current mode. Now adjust

dimmer such that total of 0.070A current flows through tertiary windings of the transformer

observing on EMT34B on current mode.

4. Now note down the readings of current. voltage & PF on EMT34A in following


minimum position.

TABULAR COLUMN:

S. No. Voltage

L-N(V)

Current

I(A)

Power


1. RN=

2. YN=

3. BN=

CALCULATIONS:

From the observation tables, calculate the following parameters

1) Positive Sequence Impedance Z1 = (Z12+Z13-Z23)/2

2) Negative Sequence Impedance Z2 = (Z12+Z23-Z13)/2

3) Zero sequence Impedance Z0 (or) Z3 = (Z13+Z23-Z12)/2

RESULT:

Exp. No: Date:

ABCD PARAMETERS & REGULATION OF A 3-PH

TRANSMISSION LINE MODEL

(i) ABCD parameters of transmission network

AIM: To determine ABCD constants of 3-phase transmission line with Distributed

Connection

.

APPARATUS REQUIRED:

S.NO Description Type Range Quantity

1 Voltmeter M.I (0-300)V 1

2 Voltmeter M.I (0-30)V 1

2 Ammeters M.I (0-10)A 2

3 Connecting wires ---- ------ As required

THEORY:

If a transmission line is erected, the constants are measured by conducting the OC & SC tests at the

two ends of the line. Using equations

Vs = AVr+ BIr

Is = CVr + DIr

Impedance measurement on the SE side: SE impedance with RE open circuit is

Vs A

Zs --- — = — (Ir=0)

Is C

SE impedance with RE short circuited,

Vs B

Zss = — = — (Vr=0)

Is D

Measurement of impedance on RE side

Using equations

Vr = DVs— BIs

Ir = — CVs + AIs

While performing test, the current leaves the Network

Is = — Is , Ir = — Ir

Vr = DVs— BIs

— Ir = — CVs— AIs

Ir = CVs+ AIs

RE impedance with SE open circuited, Zro

Vr D

Zro = — = — (Is=0)

Ir C

RE impedance with SE short circuited, Zrs

Vr B

Zrs = — = — (Vs=0)

Ir A

D B 1

Zro — Zrs = — − — = —

C A AC

Zso

ZSO = ----------- = A2

Zro - Zrs

Zso

A = √ ----------------

(Zro — Zrs)

B

Zrs = -----

A

B = Zrs .A

Zso

B = Zrs √ ------------

(Zro – Zrs)

A A 1 Zso

Zso = ----- C = ----- = --- √ -----------

C Zso Zso (Zro – Zrs)

D

Zro = ----

C

D = C.Zro

Zro Zso

D= ------ √ ---------------- (Zro = Zso)

Zso (Zro – Zrs)

D = A

CIRCUIT DIAGRAMS:

Fig-1(OC test on SE side)

Fig-2(SC test on SE)

Fig-3 (OC test on RE side)

Fig 4. (SC test on RE side)

PROCEDURE:

For O.C & S.C .tests on SE side:

1. Connect the circuit as per fig.(1) for O.C. test on SE.

2. Set 230V on Voltmeter using variac and note Vs, Is and p.f. meter reading.

3. Connect the circuit as per fig(2) for S.C.test on SE.

4. Set rated current of the line on Ammeter and note Vs,Is and wattmeter readings.

For O.C & S.C .tests on RE side:

1. Connect the circuit as per fig.(3) for O.C. test on RE.

2. Set 230V on Voltmeter using variac and note Vr, Ir and p.f. meter readings.

3. Connect the circuit as per fig(4) for S.C.test on RE.

4. Set rated current of the line on Ammeter and note Vr,Ir and wattmeter readings.

TABULAR COLUMNS:

O.C.& S.C. tests on SE side:

Test Vs Is p.f/Wattmeter

O.C(Ir=0) 230

S.C(Vr=0)

O.C.& SC tests of RE side:

Test Vr Ir p.f/Wattmeter

O.C(Is=0) 230

S.C(Vs=0)

CALCULATIONS:

𝐙𝐬𝐨 = 𝐕𝐬

𝐈𝐬(𝐈𝐫 = 𝟎)

𝐙𝐬𝐬 = 𝐕𝐬

𝐈𝐬(𝐕𝐫 = 𝟎)

𝐙𝐫𝐨 = 𝐕𝐫

𝐈𝐫(𝐈𝐬 = 𝟎)

𝐙𝐫𝐬 = 𝐕𝐫

𝐈𝐫(𝐕𝐬 = 𝟎)

PRECAUTIONS:

1. Initially 3-point starter is kept at ‘OFF’ position

2. Starter handle is moved slowly.

3. Motor Must be switched ‘off ‘with load.

RESULT:

(ii)REGULATION OF A 3-PH TRANSMISSION LINE MODEL

AIM: To determine Efficiency and Regulation of 3 phase Transmission model With R&RL

loads .

APPARATUS REQUIRED:

S. No. Item Range Quantity

1 Digital Voltmeter (0-500)Volts AC 2 No

2 Digital Ammeter (0 – 20)Amps AC 2 No

3 Wattmeter 500V/5 Amps 4 No

4 MCB protection(3-pole type)

32 Amps 1 No

5 Inductor coils 0.32milli Henry 60

6 Capacitors(440volts) 2 micro farad 60

7 Load bank(R-load) 5Amps 01

8 Indication Lamps (R,Y &B) 09

9 3-ph Transformers 415/415 Volts,7KVA 02

10 Connecting wires - As required

THEORY:

The transmission line constants are uniformly distributed over the entire length for a

short line and these constants are called lumped constants. If the length of the

transmission line is more than 200 km serious errors are introduced in the performance

calculations. Hence a equivalent T or pie network is determined to represent the line

accurately by assuming suitable values of lumped constants.

CIRCUIT DIAGRAM:

PROCEDURE

1. Make the connection as per the Circuit Diagram.

2. Switch ON supply and adjust rated voltage.

3. Note down voltage, no – load current readings.

4. Note down current and power at sending end and receiving end at no load.

5. Now switch on some load using R- load Bank provided.

6. Apply some load like 3 amps in steps wise up to 5 amps.

7. Note down all meter readings.

8. Tabulate the readings in the tabular columns.

9. Find out the efficiency and regulation using formulas.

10. Repeat the same procedure for short and medium lines.

11. Observe all parameter readings in all conditions.

12. Note down the readings and table it.

TABULAR COLUMN:

S.NO. Vs

(V)

IS

(A)

W s (W) V r

(V)

Ir

(A)

Wr (W) %Efficiency

% Regulation

W1 W2 W3 W4

CALCULATIONS:

% Voltage Regulation = 𝐕𝐬−𝐕𝐫

𝐕𝐫 × 𝟏𝟎𝟎

% Efficiency = 𝐏𝐫

𝐏𝐬 × 𝟏𝟎𝟎 =

𝐕𝐫 𝐈𝐫 𝐜𝐨𝐬Ɵ𝐫

𝐕𝐬 𝐈𝐬 𝐜𝐨𝐬 Ɵ𝐬 × 𝟏𝟎𝟎

PRECAUTION: -

1. Keep the voltage at sending end constant throughout the experiment.


RESULT:

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