THE NATIONAL INSTITUTE OF ENGINEERING

(Autonomous Institute under VTU, Belagavi)

Mysuru – 570 008

Laboratory Manual
PROTECTION LAB
Course code: EE7L02

Lab Incharge: Dr.R.Chidanandappa

Manual:

Dr.R.Chidanandappa
Associate professor

Department of Electrical & Electronics Engineering

The National Institute of Engineering
(Autonomous Institute under VTU, Belgaum)
Mysuru – 570 008

2022-23

1
 Department of Electrical and Electronics Engineering

VISION

The department will be an internationally recognized centre of excellence imparting

quality education in electrical engineering for the benefit of academia, industry and society
at large.

MISSION

 DM1: Impart quality education in electrical and electronics engineering through theory and its
applications by dedicated and competent faculty

 DM2: Nurture creative thinking and competence leading to innovation and technological
growth in the overall ambit of electrical engineering

 DM3: Strengthen industry-institute interaction to inculcate best engineering practices for

sustainable development of the society

PROGRAM EDUCATIONAL OBJECTIVES

PEO1: Graduates will be competitive and excel in electrical industry and other organizations

PEO2: Graduates will pursue higher education and will be competent in their chosen domain

PEO3: Graduates will demonstrate leadership qualities with professional standards for sustainable
development of society.

PROGRAM SPECIFIC OUTCOMES

Our Electrical and Electronics Engineering graduates will have the ability to:

PSO1: Apply the knowledge of Basic Sciences, Electrical and Electronics Engineering and
Computer Engineering to analyze, design and solve real world problems in the
domain of Electrical Engineering.

PSO2: Use and apply state-of-the-art tools to solve problems in the field of Electrical
Engineering.

PSO3: Be a team member and leader with awareness to professional engineering practice
and capable of lifelong learning to serve society.

2
 PROGRAM OUTCOMES

Engineering Graduates will be able to:

PO1: Engineering knowledge: Apply the knowledge of mathematics, science, engineering

fundamentals and an engineering specialization to the solution of complex engineering
problems.

PO2: Problem analysis: Identify, formulate, review research literature, and analyze complex
engineering problems reaching substantiated conclusions using first principles of
mathematics, natural sciences and engineering sciences.

PO3: Design/development of solutions: Design solutions for complex engineering problems and
design system components or processes that meet the specified needs with appropriate
consideration for the public health and safety and the cultural, societal and environmental
considerations.

PO4: Conduct investigations of complex problems: Use research-based knowledge and re-
search methods including design of experiments, analysis and interpretation of data and
synthesis of the information to provide valid conclusions.

PO5: Modern tool usage: Create, select and apply appropriate techniques, resources and
modern engineering and IT tools including prediction and modeling to complex
engineering activities with an understanding of the limitations.

PO6: The engineer and society: Apply reasoning informed by the contextual knowledge to
assess societal, health, safety, legal and cultural issues and the consequent responsibilities
relevant to the professional engineering practice.

PO7: Environment and sustainability: Understand the impact of the professional engineering
solutions in societal and environmental contexts and demonstrate the knowledge of and
need for sustainable development.

PO8: Ethics: Apply ethical principles and commit to professional ethics and responsibilities
and norms of the engineering practice.

PO9: Individual and team work: Function effectively as an individual and as a member or
leader in diverse teams and in multidisciplinary settings.

PO10: Communication: Communicate effectively on complex engineering activities with the

engineering community and with society at large, such as, being able to comprehend
and write effective reports and design documentation, make effective presentations and
give and receive clear instructions.

PO11: Project management and finance: Demonstrate knowledge and understanding of the
engineering and management principles and apply these to one's own work, as a member
and leader in a team, to manage projects and in multidisciplinary environments.

PO12: Life-long learning: Recognize the need for and have the preparation and ability to
engage in independent and life-long learning in the broadest context of technological
change

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Course Outcomes:

On the successful completion of the course, the student will be able to

COs Bloom’s level

CO1 Draw the operating characteristics of Fuse and Overvoltage/Under
voltage/Over current Relays, Distance, Differential and Negative Apply
sequence Relays.
CO2 Demonstrate the performance characteristics of Feeder, Generator and Apply
Motor protection schemes

Mapping with POs and PSOs:

COs PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO9 PO10 PO11 PO12 PSO1 PSO PSO3
2
CO1 3 3 3 3 3 3 1 1 3 2 1
CO2 3 3 3 3 3 3 1 1 3 2 1

S – Strong (3) M – Medium (2) L – Low (1)

4
 List of Experiments

Sl.No. COs Title of the Experiment Page

No.
CO1 Operating characteristics of static over-voltage relay and static 6
1 under-voltage relay
CO1 Current-time characteristics of Fuse. 8
2

CO1 Operating characteristics of microprocessor based over-current relay. 11

3

CO1 Operating characteristics of microprocessor based over/under 14

4 voltage relay
CO1 Study the performance of Negative sequence relay. 17
5

CO1 Operating Characteristics microprocessor-based Distance Relay. 19

6

CO1 Operating Characteristics Numerical based Differential Relay. 22

7

CO2 Simulation study of Feeder protection schemes of Radial feeder 24

8

CO2 Simulation study of Motor protection schemes 29

9

CO2 Simulation study of Generator protection schemes 35

10

5
 1. Static Under Voltage Relay

Aim: To study the definite minimum time characteristics of static under voltage relay

Apparatus Required:

Equipment’s Specifications Quantity

Static under voltage relay AUX.SUP:175-300V DC 1
Rat.Vol:230V AC
DPST 1Phase ,230V 1
Voltmeter (0-600V) 1
Autotransformer 1 Phase,(0-300V) 1
Patch cords As per required

Circuit Diagram:

6
Procedure:
1. Connections are made as shown in the figure.
2. Setting of Under voltage Vs should be done using the percentage voltage dip switch.
3. Appropriate time must be set by using the dip Switches in the relay front.
4. Switch ON the supply. Observe the characteristics of the relay by increasing the voltage. No fault
is detected so the trip signal will be off.
5. Apply the voltage below the set value Vs to test the relay. Now trip signal appears and the relay
trips and note down the trip time.
6. The trip time obtained will be same as that of the time setting which is set earlier.
7. Repeat the same from step 3 for different voltage and time setting.

Tabular Column:
Sl. Applied Voltage in Trip time in
No. Volts seconds
1
2
3
4

Model Graphs:

T1

 T2
Trip time (sec)

 Applied under voltage

Calculations:

Vn = 230V
Voltage setting = (30 to 95%) = Vn * (a)
Time setting = (0 to 25sec) =  t

Results:

Inferences:

7
 2. Current-Time Characteristics Of A Fuse

Aim: To determine the characteristics of fuse wire of constant length or constant current and also
determine the fuse constant and fuse factor.

Apparatus Required:

Equipments Specifications Quantity

Fuse Kit 5A/10A,230V 1
Fuse element 5A/10A,230V 1
Fuse wire As Per Required

Circuit Diagram:

8
Procedure:
1. Connect as per interconnection diagram.
2. Given fuses is fixed on the fuse board (for given length).
3. Make the shorting link in close position.
4. Time interval meter selection switch in TIM position.
5. Connect the power cord.
6. Bring dimmer to zero position.
7. Put ON the mains using mains ON switch (mains on indicator, ammeter display and timer display
will glow).
8. Select the current range, ranges available 1A, 2A, 5A, 10A.
9. Short switch position in short conditions.
10. Push TEST START button
11. Adjust the dimmer such that ammeter shows current greater than the current rating of the fuse wire.
12. Push TEST STOP/RESET button.
13. Don't disturb the dimmer.
14. Bring the short switch in open position - 2.
15. Push TEST START button. Ammeter shows the current time interval starts counting.
16. The time taken for the blown out of the fuse wire is noted.
17. The above procedure is repeated for different values of load current.
18. Similarly repeat the above procedure (for different lengths).
19. Plot the graphs.

Tabular Column:

Load Melting time (s)

Sl. No. current (A)
Length =cm Length =6cm

9
Model Graphs:

Calculations:
Minimum fusing current = ____________

Fusing factor =

Fuse constant = K=

Results:

Inferences:

10
 3. Microprocessor Based Over Current Relay

Aim: To study the characteristics of Microprocessor based Over Current Relay.

Apparatus Required:
1. Over current relay unit.
2. Digital Ammeter (0-10)A.
3. Stop watch
4. Current Regulator

Circuit Diagram:

11
Procedure:
1. Switch on the power supply and ensure that all the meters and relays are energized with auxiliary
power supply.
2. Switch on the Circuit Breaker (CB) using the "ON" Push button.
3. Regulate the current with current regulator to a fault current level of 2A (refer the settings info for
further details).
4. Now the trip indicator will start blinking as an indication of fault command initiated on the relay to
trip.
5. Keeping the regulator in the same position, switch off CB.
6. Test the time interval meter for its working condition by keeping the rotatory switch in test mode.
7. Reset the timer to zero.
8. Switch on the CB and time interval meter simultaneously.
9. Now, note down the ammeter & time interval meter readings after tripping of rely.
10. Switch the CB and timer & repeat the experiment for different fault current level.

Overcussent Relay Settings: MC-12A OVER CURRENT RELAYS:

1. Over Current Setting Is=50-200% Jumper setting for J1 inside, in the PCB of the relay to position
no.3 (refer instrumentation manual).
2. Selection of Trip time characteristics:
 Normal Inverse (3.0 seconds)
 Switch position: OFF OFF ON OFF
 DIP switches available on the PCB of the relay.
3. Setting fault current level (fault) for MC12A:
Is=(0.1R + RƩa)In
Where Is=Set current level (fault current level) in amps
 In = Ct rating (1A/5A).
 a=Weight of switch in ON position.
 R=Constant depending on the setting range.

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Tabular Column:

IS = 1A, TSM = 0.7 IS = 1A, TSM = 0.9

Fault Trip time Fault Trip time
IS (A) IS (A)
Current(A) (sec) Current(A) (sec)

Model Graphs:

Results:

Inferences:

13
 4. Microprocessor Based Over Voltage Relay

Aim: To Study the characteristics of Microprocessor based Over voltage relay

Apparatus Required:
1. Microprocessor based OV/UV relay testing kit.

Circuit Diagram:

14
Procedure:
1. Connect the input terminal to single phase 220V, 50Hz, AC supply after checking the values.
2. Connect the voltmeter as shown in the circuit diagram.
3. Switch ON power supply at the source.
4. Switch ON the MCB, on the testing kit and look for „Power ON‟ indication.
5. Ensure „0‟ display in the timer and voltmeter.
6. Test the operating of timer by keeping the rotary switch in test mode and switching ON the circuit
breaker, reset the time after testing.
7. Set the relay voltage Vs to desired value by operating the dip switch ON relay front.
8. Set the Time Setting Multiplier (TSM) to desired value by operating the connect dip switches on
relay front.
9. Keeping the selector switch to „Set mode‟ switch ON the CB.
10. Adjust the voltage regulator to a desired voltage and note down the same. Switch off the CB.
11. Keeping the regulator at the adjusted position change the Selector switch to „Test mode‟.
12. Switch on the CB and Note down the tripping time of CB.
13. Repeat the steps 10 to 13 for 4-5 voltage values in the increasing order in steps of 10% for two
TSM values and plot the graph of time V/S fault voltage.

Tabular Column:

1. Fault Voltage Settings: Over Voltage Mode : 105% to 180% of rated voltage in steps of 5%.
2. Time Setting Multiplier : 0.1 to 1.6 in steps of 0.1

TSM=0.7 sec TSM=0.8 sec

Sl. No. Fault Voltage (Vf) Trip Time (sec) Fault Voltage (Vf) Trip Time (sec)

15
Model Graphs:

Calculations:
 Nominal voltage: Vn = 110 V
 Set Voltage: Vs = [1 ± (0.05 + Ʃ a)]Vn in volts
 Time setting multiplier: TSM = K (0.1 + Ʃ t) in seconds
 K= 3.5 for Normal inverse characteristics

Results:

Inferences:

16
 5. Static Negative Phase Sequence Current Relay

Aim: To study the Negative phase Sequence current relay characteristics.

Apparatus Required:

Equipment’s Specifications Quantity

Static Negative phase Sequence
230V 1
current relay unit.
Negative phase Sequence current
230V 1
relay test kit
0.35kW,0.5HP,
Three phase Induction Motor 1
415V,1.1A
Patch Cords As per required

Circuit Diagram:

17
Procedure:
1. Connect the circuit as shown in the figure.
2. Connect the Auxiliary power cord to Negative phase Sequence current relay kit.
3. Rheostat should be in cut – out position (Balance condition).
4. Switch on Main supply, push CB “ON” button - circuit breaker ON indicator will glow and motor
starts running (if motor is not running interchanging any two phase ) note down the ammeter
reading and relay time in seconds.
5. Switch off the main supply adjust the resistance (Rh) in Ω using Rheostat in phase R to create the
Negative Sequence (Unbalance condition).
6. Switch on Main supply push CB “ON” button. Note down the ammeter reading and trip timings.
7. The procedure for Unbalance condition is repeated for different Rh values and tabulates the
readings.
8. Change the Phase sequence in the supply connection and observe the relay operation and tabulate
thye same
9. Comment on Negative phase Sequence current relay characteristics.

Tabular Column:
Balance condition:

Trip Time
Sl.No Current in phase R Current in phase Y Current in phase B
in Seconds

Unbalance condition:

Trip Time
Sl.No Current in phase R Current in phase Y Current in phase B
in Seconds

Phase sequence:

Phase
RYB RBY YBR
sequence
Trip Time
in Seconds

Results:

Inferences:
18
 6. Microprocessor Based Impedance Relay

Aim: To study the characteristics of microprocessor based impedance relay.

Apparatus Required:

Equipments Specifications Quantity

Impedance based relay unit 1,230V,50HZ 1

Impedance based relay test kit 1,230V,50HZ 1

Patch cords AS PER REQUIRED

Circuit Diagram:

Procedure:
1. Connect the circuit as shown in the diagram. Bring both dimmer to zero position.
2. Turn on mains switch in the source kit, mains on indicator, ammeter, voltmeter and time interval
meter display turns on.
3. Put the SET/TEST switch to SET mode.
4. Press the start push button.
5. By using variac-1 set the voltage to 220 V and using Variac-2, set the current to 1A in the
voltmeter and ammeter respectively.
6. Now, check whether the impedance in the impedance meter is Z= 100%.
19
 7. Now, create fault, it is done either by increasing current or by decreasing voltage to the impedance
such that percentage impedance is less than 100%.
8. Press STOP/RESET push button, change the SET/RESET switch to TEST mode.
9. Press the button on the relay to start.
10. Again press the start push button on the source exit.
11. The relay trips, note down the trip time, distance, current voltage, percentage impedance on the
impedance meter.
12. Repeat the procedure for two different values of voltage and current and note down the meter
reading.

Note: The meter is programmed for a protection range of 400 km.

i.e., 400 kms = 100% impedance.
Hence change in voltage & current results in change in percentage impedance.
Example: If relay is set 100% impedance i.e. voltage is 220 V and current is I A.

% impedance = *100

= 100=100%

Assume for the transmission line of 400 km impedance is 220 Ω i.e., 100%, hence the impedance per
km is 0.55 Ω. The relay was tripped at 70% of impedance.

i.e... Z = = 154Ω

Fault occurred at a distance of = = 280 km

For 400 km impedance = 100%

For 70% Impedance = 280 km

Tabular Column:

Sl. No. Voltage (V) Trip Time Distance Current (A) %

(sec) (km) Impedance
(Z)

20
Model Graphs:

Calculations:

Results:

Inferences:

21
 7. Static Biased Differential Relay

Aim: To study the static biased differential relay characteristics.

Apparatus Required:
1. Static biased differential relay unit.
2. % Differential Relay test kit.
3. Patch cords.

Circuit Diagram:

Procedure:
1. Connect the relay test kit to the main supply 230V, 50HZ.
2. Connect the circuit as per the following.
a) Connect 13&14 to 230V ac supply provided in the source unit. Also connect ground.
b) Connect the NO point of circuit breaker to 1&3 terminals of static biased differential relay unit.
c) Short S2 of both CT‟s & connect to terminal 27 of static biased differential relay unit. Connect
S1 of primary CT to terminal 23 and S1 of secondary CT to terminal 25 of static biased
differential relay unit.
d) Short the terminals 24, 26 & 28 of static biased differential relay unit.
3. Set the IS (setting current) of differential relay unit (0.1 to 0.5).
4. Initially apply equal current on primary as well as secondary side of CT (say 1A) using Variarc 1 &
Variarc 2. Observe ammeter 1 & ammeter 2 to be equal.

22
 5. Then gradually decrease one of the current value keeping other constant (can be primary of
secondary side).
6. Note down the current at which the relay trips.
7. Repeat the same procedure for different values of current (for five values) for a particular value of
Is.
8. Plot the characteristics of differential relay for two different Is settings.

Tabular Column:

Sl. Primary side secondary Differential Effective

No. CT current side CT current I1–I2 bias current
(A1) amps (A2) amps I1+I2

Model Graphs:

Calculations:

Results:

Inferences:

23
 8. Simulation study of Feeder Protection Schemes

Aim: To study the feeder protection simulation unit.

Apparatus Required:
1. Feeder protection simulation study unit.

Circuit Diagram:

24
Procedure:

1. Connect 3-phase 4 wire power supply to the panel.

2. Connect the 3-phase load to the panel.
3. Switch on the main control and relays for all the zones.
4. Set the program for the relay as follows.
a) Press select, go to “ProG” by the down arrow key.
b) Simultaneously press up and down keys till we get “P.SET”.
c) Press enter key, display shows “OC” then press enter key to set current value.
d) Press twice enter key to get “OC. Ch” then enter key to set time characteristics.
e) Press twice enter key to get “OC. ts” then set time.
f) Similarly EF (Earth Fault), EF. Ch (Earth fault characteristics), EF. ts (Earth fault time settings)
can be set in the program.
5. Switch on the circuit breaker (CB) 1, 2, 3, 4.
6. Switch on the resistive load bank and for over current individual switches on each Phase should be
“ON”. Then switch ON the CB–5 (load side).
7. Observe the trip time and circuit breaker indicator. Ensure that trip time matches with relay time
setting and respective zone, note down the readings, and press reset button.
8. Switch OFF the zone – 1 relay, then Circuit breaker (CB) – 5 ON, observe the trip time and circuit
breaker indicator for zone – 2 and note down the reading.
9. For Earth fault, individual switches on the load bank for one phase only, then Switch ON the
Circuit breaker (CB) –5.
10. Observe the trip time and indicator, note down the readings.
11. Plot the Relay characteristics curves and Comment on each results and setting of the relay.
12. Follow the tables to set current and time characteristics of three grading methods for over current
and earth fault relay for all the zones.

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Table1: Time Grading

Characteristics Zone 1 Zone 2 Zone 3 Zone 4

Over current pickup setting -OC 0.4 0.4 0.4 0.4

Over current characteristic setting d10 d10 d10 d10
-OC.Ch
Over current Time multiplier 0.8 0.6 0.4 0.2
setting-OC.ts
Earth fault pickup setting -EF 0.2 0.2 0.2 0.2
Earth fault characteristic setting – d10 d10 d10 d10
EF. Ch
Earth fault Time multiplier 0.8 0.6 0.4 0.2
setting- EF. Ts

Table1: Current Grading

Characteristics Zone 1 Zone 2 Zone 3 Zone 4

Over current pickup setting -OC 0.55 0.5 0.45 0.4

Over current characteristic setting -
nI 3 nI 3 nI 3 nI 3
OC.Ch
Over current Time multiplier
1 1 1 1
setting-OC.ts
Earth fault pickup setting – EF 0.6 0.5 0.4 0.2
Earth fault characteristic setting –
nI 3 nI 3 nI 3 nI 3
EF. Ch
Earth fault Time multiplier setting-
1 1 1 1
EF. Ts

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Tabular Column:

OVER CURRENT PROTECTION

Load L1 (A) L2(A) L3(A) Secondary Tripping time in sec

Switches current Zone Zone Zone Zone 4
(A) 1 2 3
I
II
III
IV
V

EARTH FAULT PROTECTION

L1 (A) L2(A) L3(A) Secondary Zone Zone Zone Zone 4

current 1 2 3
(A)
One
Phase
load only

IEC 60255 Characteristics :

27
Model Graphs:

Results:

Inferences:

28
 9. Simulation study of Motor Protection Schemes

Aim: To study the motor protection simulation unit.

Apparatus Required:
1. Motor protection simulation study unit.
2. Motor- 3 phase, 415V, 4.8A, 1410 RPM, 50Hz.

Circuit Diagram:

29
Procedure:
1. Connect 3-phase 4 wire power supply to the panel.
2. Connect Voltmeter and Ammeter.
3. Switch on the main control and MCBs.
4. Set the 3-phase voltages equal.
5. Set the program for the respective protection as follows.

I. Phase failure protection

1. Bring all the fault simulation to position1.

2. Switch on fault simulation single phase.
3. Ensure the Electronic Motor Protection Relay (EMPR) settings
a) Inverse/ Definite characteristic – Definite
b) Definite time – 2 sec.
c) Reverse phase protection – ON
d) Under current protection – OFF
e) Ground fault – 0.05 sec
f) Stall function – ON
g) Lock function – ON – 200%
h) CT Ratio – 1
i) Phase failure – ON
j) Store
k) Current – 2A
4. Switch ON the motor.
5. Note down the timer reading.
6. Relay trip occurs–
a) Motor will be stop.
b) Relay display shows – PF bar graph will be turn ON.
c) Hooter will be ON.
d) Fault indicator will be glow
7. Now accept the fault by pressing the accept pushbutton.
8. Reset the relay by pressing test/reset button.
9. Press the Reset button at control panel.
10. Bring single phase fault simulation switch to home position1.

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 Table: Phase failure protection

conditions Motor Ammeter readings Voltmeter Hz RPM PF Trip time

R Y B RY YB BR
Normal

Phase
failure

II. Phase reversal protection

1. Switch ON the power supply of motor protection.

2. Set the line voltages equal and ensure motor is OFF.
3. Bring all the fault simulation to position1.
4. Switch ON phase reversal fault simulation to position2.
5. Ensure the EMPR settings.
a) Inverse/ Definite characteristic – Definite
b) Definite time – 2 sec.
c) Reverse phase protection – ON
d) Under current protection – OFF
e) Ground fault – 0.05 sec
f) Stall function – ON
g) Lock function – ON – 200%
h) CT Ratio –1
i) Phase failure – ON
j) Store
k) Current –2A
6. Switch ON the motor.
7. Relay trip occurs–
a) Motor will be stop.
b) Relay display shows – r-p bar graph will be turn ON.
c) Hooter will be ON.
d) Fault indicator will be glow.
8. Now accept the fault by pressing the accept pushbutton.
9. Reset the relay by pressing test/reset button.
10. Press the Reset button at control panel.
11. Bring single phase fault simulation switch to home position1.

31
 Table: Phase reversal protection

conditions Motor Ammeter readings Voltmeter Hz RPM PF Trip time

R Y B RY YB BR
Normal

Phase
reersal

III. Overcurrent Protection

1. Adjust the overcurrent setting in the motor protection relay to 2.5A considering that as a normal
load current.
2. Set the motor protection relay parameters (remains same).
3. Switch on the motor.
4. Gradually load the motor using the dynamometer while observing the current in ammeter. (Note
down ammeter and timer readings when the relay operates).
5. Relay trip occurs.
a) Motor will stop
b) Relay display shows O-L bar graph will be turn on
c) Hooter will be on
d) Fault indicator will be glow
6. Now accept the fault by pressing the accept push button.
7. Reset the relay by pressing test/reset button.
8. Press the reset button at control panel.
9. Bring fault ground fault simulation switch to home position (1).
10. Again switch on the motor and record the voltage and current etc.

Table: Overcurrent protection

Frequ
Speed Power Trip time
Sl.No Motor Ammeter readings Voltmeter (V) ency
(RPM) Factor (Sec)
(Hz)

R Y B RY YB BR

32
IV. Ground leakage/ Earth leakage protection

1. Ensure motor is OFF. Connect the Ammeter A2 to measure the leakage current.
2. Bring all fault simulation to position 1.
3. Short the rheostat terminal using patch cord phase to earth
4. Ensure EMPR settings. Set the motor protection parameters with Under current protection “ON”
30% to 70%.
5. Switch ON the Ground Leakage / Fault simulation switch to position 2.
6. Switch ON the motor and record the data.
7. Relay trip occurs.
8. Now accept the fault and reset EMPR and panel.
9. Bring fault simulation switch to position 1.

Table: Ground leakage protection

Details Motor Ammeter Frequ Power Trip

Voltmeter (V) Speed
readings ency Factor time

R Y B RY YB BR Hz RPM - Sec

Before Fault

After Fault

IV. Power Factor Correction

1. Ensure motor is OFF and Bring all fault simulation to position 1.

2. Set voltage all the phase voltages are equal.
3. Release the motor load.
4. Start the motor.
5. Load the motor 5A.
6. Switch on the capacitor bank switch pos1 and pos2, Note down the readings.

33
 Table: Power Factor Correction

Details Motor Ammeter Frequ Power Trip

Voltmeter (V) Speed
readings ency Factor time

R Y B RY YB BR Hz RPM - Sec

Without
Capacitor
With
Capacitor
1KVAr
With
Capacitor
2KVAr

Results:

Inferences:

34
 10. Simulation study of Generator Protection Schemes

Aim: To simulate the Generator Protection scheme.

Apparatus Required:
1. Generator protection simulation study unit:
2. MOTOR: 415 V DELTA - 2.2KW, 3HP, 1415 RPM, 4.5A
3. ALTERNATOR: kirloskar, 3KVA, 4.5A 3 Ph, 1500RPM, with R phase 2 tapings
4. INVERTOR: ( variable frequency drive), MAKE- LG, Model-SV -022 - iG5 – 4.3 HP
5. PROTECTION RELAYS:
a) Numerical % differential relay - C&S make
b) Numerical over current relay - MC61A, L&T make
c) Numerical OV/UV relay - L&T Make. - MV12
d) Hz relay - Hvileic make.
e) Temperature indicator with relay. - Selectron make
f) Negative sequence relay - Alstom make.

Circuit Diagram:

35
Procedure:
1. Merz-Price Protection OR Differential protection Relay
1. To create the internal fault inside the generator, connect any one of the phase terminal of generator
to neutral.
2. Keep the switch the fault simulation knob to 1 position.
3. Start the generator as per the sequence :
 Connect 3 phase, 4 wire to the panel.
 All fault selector switch must be in position 1.
 Switch on the mains MCB, all meter display and power indications of RYB will be glow.
 Press inverter ON (VFD) push button, inverter display will be ON.
 Motor starts to rotate, adjust the rpm to 1500 rpm by potentiometer.
4. CB must ON and build up generator voltage up to rated level 230v through DC excitation by
varying variac.
5. To simulate the fault by switch the fault simulation knob to 2 position.
6. Due to internal fault, differential protection relay will operate and relay indicator ON and it will
trip the circuit breaker CB1.
7. Hooter will glow, generator trips.
8. Accept the fault by pressing accept push button and reset push button.
9. Bring back fault simulation switch to 1 position.
10. Bring back excitation to zero.
11. Repeat this step to verify for different phase to neutral short circuit and operation of the differential
protection relay.

Tabular Column:

Generator voltages in volts Generator

Sl no
ON/OFF
L1 L2 L3
Before fault

After fault

2. Over current protection:

1. Connect resistive load in star connection to the load points of generator, keep fault simulation
switch to position 1.
2. Start the alternator as per the sequence.

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 3. Set the OC/EF relay setting as per the program below
 Over current lower setting : 0.35
 Over current higher setting : 2.0
 Over current characteristics : nI 3sec
 Over current time settings : 1.00
 Earth fault lower settings : 0.2
 Earth fault higher setting : 1.0
 Earth fault characteristics : n1 1.3sec
 Earth fault time settings : 1.0
4. Toggle switch OC/EF is positioned to healthy side.
5. Increase the load on the generator and switch ON load CB-2.
6. Change the position of fault simulation switch to 2
7. Note down the meter readings.
8. Note down the time of operation of relay.
9. Repeat the above procedure for different loads.

Tabular Column:
CASE: ts=0.5 Sec, NI=3sec, Is=2A

Resistive IR(A) IY(A) IB(A) Trip time in

SL.NO
load position sec
1 20%
2 40%
3 60%
4 80%
5 100%

3. Earth fault protection:

1. To simulate earth fault, switch ON load on any one phase only, remaining phase loads should be
kept OFF.
2. OC/EF is kept in healthy condition and fault simulation switch to position to 1.
3. Switch ON the load CB-2.
4. Change the fault simulation switch to position-2.
5. Note down the time of operation of relay.
6. Repeat above procedure by decreasing the operating load.

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Tabular Column:

Resistive load
bank Case 1 Case 2 Case 3 Case 4 Case 5
switches
1 ON ON ON ON ON
2 OFF ON ON ON ON
3 OFF OFF ON ON ON
4 OFF OFF OFF ON ON
5 OFF OFF OFF OFF ON
Relay trip
time (sec)

4. Frequency relay protection:

1. Start the generator as per the sequence

2. Set the Hertz relay to healthy condition
3. Set the upper and lower limits of frequency in frequency meter setting.
4. Vary VFD to change the frequency according to setting.
5. Observe the tripping time of the relay.

Tabular Column:

Frequency meter Operating Relay

Upper limit Lower limit frequency ON/OFF

5. Temperature relay protection

1. Start the generator as per the sequence.

2. Set the temperature relay to the healthy position.
3. Set the temperature limit in the meter.
4. Run the alternator quite long time and allow machine to get heated.
5. When temperature of winding exceeds the set value of temperature relay trips. Observe the tripping
time of the temperature relay.

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Tabular Column:

Set temperature Operating temperature Generator ON/OFF

Results:

Inferences:

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