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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
6. Capacitors. 10 micro Farad 04
7. Capacitors. 1 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:
1. Avoid loose connections.
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
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) Z23=V/I
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
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) Z13=V/I
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.
2. Avoid loose connections.
RESULT:
Recommended