Hv Manual

INSTRUCTIONS TO THE STUDENTS

1. Students should attend the laboratory wearing prescribed uniform and rubber shoes.

2. Students should come with thorough preparation for the experiments including the

theory, aim, procedure, calculations and the answers to the vive questions.

3. Students will not be permitted to attend the laboratory unless they bring the Practical

Record fully completed in all respects pertaining to the experiments conducted in the

previous class.

4. Students shall write the Aim, Circuit Diagram, Formulae used and Blank Tabular

Columns for the experiment in the observation book before coming to the laboratory.

5. The procedure for the experiments shall be explained to the staff member by the student

before making the necessary circuit connections / start of software part.

6. After making all the connections, the student shall show the same to the concerned staff

member and then start the experiment.

7. The student shall not lean on the table / energized instruments while conducting the

experiments.

8. In case of power supply failure during conduction of the experiments, the student shall

immediately switch off the main power supply switch. After the supply resumes, all the

circuit connections shall be brought back to the initial condition before restarting the

experiment.

9. On completion of the experiment, all the relevant details such as tabular column,

calculations, graphs etc., shall be completed in the laboratory, and the student shall take

the signature of the concerned staff member on the same day.

Student shall refer to the standard textbooks on the subject and include all the necessary

details in the practical record as per the instructions of the concerned staff member.

VII Semester Relay & High Voltage Lab Manual

Acharya Institute of Technology

Soldevanahalli, Bangalore – 107

Department of Electrical and Electronics Engineering

Lab: Relay & High voltage Sub code: 10 EEL 77

Semester: VII

List of the experiments for the academic year 2013-14

SL

.No. Name of the experiment

1 Operating characteristics of IDMT under voltage electromechanical

relay

2 Operating characteristics of electromechanical IDMT over current relay

3 Operating characteristics of Microprocessor based over/under voltage

relay

4 Operating characteristics of Negative phase Sequence static relay

5 Operating characteristics of Microprocessor based over current relay

6. Operating characteristics of microprocessor based impedance- distance

relay

7 D Digital motor protection Relay study unit

8 O Operating characteristics of static % differential relay

9 Breakdown strength of transformer oil using oil-testing unit.

10 Spark over characteristic of air insulation subjected to High voltage AC

with spark over voltage corrected to STP.

11 Spark over characteristics of air insulation subjected to High voltage

AC for uniform and non-uniform field configuration

12 Measurement of HVAC using standard spheres.

13 Spark over characteristic of air insulation subjected to High voltage DC

with spark over voltage corrected to STP

14 Measurement of HVDC using standard spheres.

15 Spark over characteristics of air insulation subjected to high voltage

impulse


Sub Code : 10EEL77 I.A Marks: 25

Hrs/week : 03 Exam. Hours: 03

Total Hrs : 52 Exam Marks: 50

Contents

SL

.No.

Particulars

Page No.

1 Operating characteristics of IDMT under voltage

electromechanical relay

1-4

2 Operating characteristics of electromechanical

IDMT over current relay

5-10

3 Operating characteristics of Microprocessor based

over/under voltage relay

11-18

4 Operating characteristics of Negative phase

Sequence static relay

19-22

5 Operating characteristics of Microprocessor based

over current relay

23-30

6. Operating characteristics of microprocessor based

impedance- distance relay

31-34

7 Digital motor protection Relay study unit 35-50

8 O Operating characteristics of static % differential

relay

51-54

9 Breakdown strength of transformer oil using oil-

testing unit.

55-58

10 Spark over characteristic of air insulation subjected

to High voltage AC with spark over voltage

corrected to STP.

59-62

11 Spark over characteristics of air insulation subjected

to High voltage AC for uniform and non-uniform

field configuration

63-66

12 Measurement of HVAC using standard spheres. 67-70

13 Spark over characteristic of air insulation subjected

to High voltage DC with spark over voltage

corrected to STP

71-74

14 Measurement of HVDC using standard spheres. 75-78

15 Spark over characteristics of air insulation subjected

to high voltage impulse

79-82

16 HV lab questions 83-84


Cycle of experiments

Cycle- 01

Sl.

No

Name of the experiment

1 Operating characteristics of IDMT under voltage electromechanical relay

2 Operating characteristics of electromechanical IDMT over current relay

3 Operating characteristics of Microprocessor based over/under voltage

relay

4 Operating characteristics of Negative phase Sequence static relay

Cycle- 02

Sl.

No

Name of the experiment

1 Operating characteristics of Microprocessor based over current relay

2 Operating characteristics of microprocessor based impedance- distance

relay

3 Digital motor protection Relay study unit

4 Operating characteristics of static % differential relay

Cycle- 03

Sl. No Name of the experiment

1 Breakdown strength of transformer oil using oil-testing unit.

2 Spark over characteristic of air insulation subjected to High voltage AC


3 Spark over characteristics of air insulation subjected to High voltage AC

for uniform and non-uniform field configuration

4 Measurement of HVAC using standard spheres.

5 Spark over characteristic of air insulation subjected to High voltage DC


6 Measurement of HVDC using standard spheres.

7 Spark over characteristics of air insulation subjected to high voltage

impulse


Department of EEE, ACIT, Bangalore 1

CIRCUIT DIAGRAM:

Figure 1

Figure 2



Experiment No.: 1 Date:

OPERATING CHARACTERISTICS OF IDMT UNDER VOLTAGE

ELECTROMECHANICAL RELAY

AIM: To Study the operations of IDMT under voltage Electromechanical relay and to draw

its operating Characteristics.

Apparatus required:

SlNo. Name Quantity

1 IDMT Under voltage relay & test kit

2 Connecting Leads

Procedure:

1. Connect as per interconnection diagram.

2. Set the relay for UNDER voltage level. (Range 50,60,70,80 & 90)% .(PLUG)

3. Set TMS. (Range 0 – 1)

4. Ensure Time interval meter selection switch is in TIM position.

5. Ensure S2 switch is ON position.

6. Bring both dimmers to zero position.

7. Bring Toggle switch to ‘SET’ mode.

8. Connect the power card.

9. Put on the mains using “Mains ON” switch.(ROCKER). Mains on indicator, ammeter

display, relay power and Timer display will glow.

10. Adjust the voltage level above the threshold level of under voltage relay setting. (Using

dimmer 1).

11. Push TEST START BUTTON, “CB ON” Indicator will glow.

12. Adjust the under voltage level (i.e. Less than relay set voltage) using dimmer 2.

13. Push TEST STOP/RESET button.

14. Don’t disturb the dimmer1 & 2.

15. Bring Toggle switch to ‘TEST’ mode.

16. Push TEST START BUTTON, Note down the voltage. (Circuit breaker ON, CB ON

indicator will glow, time interval meter starts up counting. Under Voltage relay trip occurs

‘TRIP” indicator will glow. If buzzer switch is on it gives the beep sound.

17. Note down the Time Interval Meter reading. (Drop off time)



Tabular column:

Plug setting (set voltage of under voltage relay): eg.99v

Time multiplier setting (TMS):eg.1

Normal inverse -5 sec curve:

Sl.no. TSM

(Time

setting

Multiplier)

SET VOLTAGE

Fault

VOLTAGE

% of closing voltage Operating time

in seconds.

(Actual Time

of Operation

of relay )

1 1 99 79.2 80 13.61

2 2 99 59.4 60 7.69

3 3 99 39.6 40 5.93

4 4 99 0 5.0SEC

% of closing voltage= (Fault voltage / Set voltage)*100

Tabular Column

SI.No. TMS ( Time

Multiplier

setting)

SET

Voltage

Fault

Voltage

% of Closing

Voltage

Operating

Time in

Seconds

1.

2.

3.

4.

5.

6.



18. Press the RESET button.

19. Repeat operation (10 – 19) by adjusting different voltage & TMS settings.

20. Draw the graph between Trip time Vs % of closing voltage

Viva questions:

1) What is a Relay?

2) Name the components of protective relaying scheme.

3) What is TSM?

4) List the applications of Electromagnetic relays.

5) What is IDMT characteristic of a relay?

6) What is reset or dropout ratio of a relay?

Questions:

1) Conduct a suitable experiment on the given Electromechanical under Voltage relay to

draw its operating characteristics. Choose the plug setting of _____ V & TMS _____.

Result &Conclusion:

Signature of staff



CIRCUIT DIAGRAM:

Fig.1 CONNECTION DIAGRAM OF RELAY

CB

CT TRIP1 Ph

,230

Vac

TRAN

SFO

RMER

RELAY UNDER TESTF S1

S2

CI

AUX.

VARIAC

POT.FREE CB

NO

NC

CONTROL CIRCUIT

TIME INTERVAL

METER

A

R

Fig.2 Connection Diagram



Experiment No:2 Date:

OPERATING CHARACTERISTICS OF ELECTROMECHANICAL

OVER CURRENT RELAY

AIM: To Study the Inverse trip-time characteristics of Over current relay

Apparatus:

Sl.No. Name Quantity

1 Electromechanical over current relay kit

2 Connecting Leads

Procedure:

1. Set the relay current using plug setting=2Amps.

2. Set TMS=1.

3. Ensure Time interval meter selection switch in TIM position.

4. Ensure Protection time switch is ON position.


6. Bring dimmer to zero position.

7. Using RB20 select the test current.

8. Put on the mains using Mains on switch.(ROCKER). Results (Mains on indicator,

ammeter display, relay power and Timer display will glow.)

9. Bring Toggle switch “SET’ mode.

10. Push TEST START BUTTON, CB ON Indicator will glow.

11. Adjust the dimmer set the approximate injection current (within 30 seconds otherwise

protection timer will activate and circuit breaker will be off.

12. Push TEST STOP/ RESET BUTTON.

13. Don’t disturb the dimmer.

14. Bring Toggle switch “TEST’ mode.

15. Push TEST START BUTTON, Note down the current. (Circuit breaker ON, CB ON

indicator will glow, time interval meter starts up counting, Protection timer starts

down counting, over current relay trip occurs TRIP indicator will glow at relay and

injector unit also. If buzzer switch is on it gives the beep sound.

16. Note down the Time Interval Meter reading. (Pick up time)


18. Repeat operation (7 – 17) by adjusting different Current & TMS settings.



19. Draw the graph Trip time Vs PSM (plug setting Multiplier.)

Tabular column:

PLUG SETTING ( SET CURRENT OF RELAY):

Time multiplier setting (TMS) :1

Sl.no. TSM(Time

setting Multiplier)

Plug

Setting

Fault

Current

PSM ( plug setting

Multiplier )

Fault ct/plug setting

Operating time in

seconds. (Actual Time of Operation of relay)

1

2

3

4

5

6

7

8



CALCULTAION:

How to find out the PSM (Plug setting Multiplier)

Fault Current

PSM = ---------------------------------

Plug setting

If CT used

Fault Current (primary current)

PSM = ---------------------------------------------------------------------------

Plug setting (Primary Setting Current) x CT ratio

Actual Operating time (Ta) in sec.

TSM = ---------------------------------------------------------------------

Calibrated Operating Time for TSM = 1.0 (Tc) in sec

Characteristics Curve to be draw = Trip Time Vs PSM

EXAMPLE:

Relay current setting is 150% ( relay 100%=5A) and has Time multiplier setting of 0.5,

the relay has connected in the circuit through a C.T. having ratio 500:5 amps 500/5A

Fault current is 6000Amps. Relay characteristics as assume for PSM 8=3.15sec at TMS is

1.

Solution:

150 % = 1.5A

5

See fault current 6000A x ----- = 60A

500

1

Plug setting multiplier PSM = 60 x ---------- = 8

5 x 1.5

Time from graph against this multiplier is 3.15sec.

Operating time = 3.15 x 0.5 = 1.575sec.



Graph.1 Characteristics Curve

TIME vs PSM

0.00

2.50

5.00

7.50

10.00

12.50

15.00

17.50

20.00

22.50

25.00

27.50

30.00

1 10 100

PSM

TIM

E



Viva questions:

1) List the essential qualities of protective relaying.

2) What is reliability of the relay system?

3) Explain sensitivity, speed and selectivity of the relay system.

4) Explain the working principle of Directional over current relay

5) What is PSM?

6) Sketch IDMT characteristics of over current relay.

7) What is the working principle of an electromagnetic relay?

Questions:

1) Conduct a suitable experiment on the given Electromechanical over Current relay to draw

its operating characteristics. Choose the plug setting of _____ A & TMS _____.

Result &Conclusion:

Signature of staff



CIRCUIT DIAGRAM:

Fig.1 CONNECTION DIAGRAM OF RELAY

CB

VA

RIA

C-1

VA

RIA

C-2

TRIP1 P

h,2

30V

ac

RELAY UNDER TEST

NC

NO

POT.

FREE

F S1

S2

V.T

S3

V

V1

V2

AU

X.

CB

CONTROL CCT.

TIME INTERVAL

METER

Fig.2 CONNECTION DIAGRAM



Experiment No.:3 Date:

OPERATING CHARACTERISTICS OF MICROPROCESSOR BASED

OVER/UNDER VOLTAGE RELAY

AIM: To study the operating characteristics of a Microprocessor based over/under voltage

relay

Apparatus:

Sl.No. Name Quantity 1 Microprocessor based over/under voltage relay&

test kit

2 Connecting Leads

Procedure– µP BASED OVER VOLTAGE RELAY TEST KIT.


2. Set the relay over voltage – (Setting procedure – refer LT MANUAL).

3. Set TMS.






9. Put on the mains using Mains on switch (ROCKER). Results (Mains on indicator,


10. Bring Toggle switch ‘SET’ mode.


12. Adjust the dimmer2 set the approximate injection voltage.( within 30 seconds

other wise protection timer will activate and circuit breaker will be off.

13. Push TEST STOP/RESET BUTTON.


15. Bring Toggle switch ‘TEST’ mode.

16. Push TEST START BUTTON, Note down the voltage. (Circuit breaker ON, CB

ON indicator will glow, time interval meter starts up counting, Protection timer

starts down counting, over voltage relay trip occurs TRIP indicator will glow at

relay and injector unit also. If buzzer switch is on it gives the beep sound.



Tabular column:

PT rating – 110V

Plug setting vs. (set voltage of over voltage relay): eg.105% i.e. 115.5V


Normal INVERSE

Sl. No. TSM (Time

setting multiplier)

Set

Voltage

Fault

Voltage

Multiple Of Set Voltage

(Vs) Fault Voltage/plug setting voltage

Operating time in

seconds. (Actual Time of Operation of relay )

1

2

3

4

5

Vs= [1+ (0.05+∑a)] Vn

T=K (0.1+∑t)

Tabular column:

Plug setting (set voltage of under voltage relay): eg.95% i.e. 104.5v

Time multiplier setting (TMS): eg.1

Vs= [1-(0.05+∑a)] Vn

NORMAL INVERSE

Sl.

No.

TSM (Time

setting Multiplier)

Set Voltage

Vs

Fault

Voltage

Multiple of Set

Voltage (Vs) Fault

voltage/set

voltage Vs

Operating time in

seconds. (Actual

Time of Operation

of relay)

1

2

3

4

5



17. Note down the Time Interval Meter reading. (Pick up time)


19. Repeat operation (10 – 18) by adjusting different Voltage & TMS settings.

20. Draw the graph Trip time Vs PSM (plug setting Multiplier.)

NOTE: For finding up the pickup voltage, protection timer switch in by pass position, and

mode switch kept at test position.

After test start gradually increase the dimmer-2 from zero to your voltage set value

and when the trip indicator led starts blinking note down the pickup voltage.

Procedure – µP BASED UNDER VOLTAGE RELAY TEST KIT


2. Set the relay UNDER voltage – (Setting procedure – refer LT MANUAL).

3. Set TMS.





8. Bring Toggle switch ‘SET’ mode.


10. Put on the mains using Mains on switch. (ROCKER). Results (Mains on indicator,


11. Adjust the voltage level above the threshold level of under voltage relay setting using

dimmer 1.

12. Push RESET and TEST START BUTTON, CB ON Indicator will glow.

13. Adjust the under voltage level (i.e. Less than relay set voltage) using dimmer 2.

within 30 seconds other wise protection timer will activate and circuit breaker will be

off.( to avoid activation of protection timer use by pass switch of that timer)

14. Push TEST STOP/RESET BUTTON.


16. Bring Toggle switch ‘TEST’ mode.

17. Push TEST START BUTTON, Note down the voltage. (Circuit breaker ON, CB ON

indicator will glow, time interval meter starts up counting, Protection timer starts



Tabular column:

Plug setting (set voltage of over voltage relay): eg.120V


Definite Time: 10SEC

Sl. No. TSM

(Time setting

Multiplier)

Set

Voltage

Fault

Voltage

Multiple of Set

Voltage (Vs)

Fault Voltage/plug setting voltage

Operating time in

seconds. (Actual

Time of Operation

of relay)

1

2

3

4

5



down counting, over voltage relay trip occurs TRIP indicator will glow at relay and

injector unit also. If buzzer switch is on it gives the beep sound.

18. Note down the Time Interval Meter reading. (drop off time)


20. Repeat operation (11 – 19) by adjusting different voltage & TMS settings.

21. Draw the graph Trip time Vs MSM.

NOTE: For finding up the drop off voltage, protection timer switch in by pass position, and

mode switch kept at test set position. Dimmer 2 voltages beyond the threshold level

After test start gradually decrease the dimmer-2 from zero to your current set value

and when the trip indicator led starts blinking note down the drop off voltage.



Tabular column: Plug setting (set voltage of under voltage relay): eg.100V


Definite Time: 10 SEC

Sl. No. TSM (Time setting

multiplier)

Set

Voltage

Fault

Voltage

Multiple of set

voltage (Vs)

Operating time in

seconds. (Actual

Time of Operation

of relay)

1

2

3

4

5

For trip time at TMS other than 1

Trip time= (trip time at TMS=1) x TMS



Viva questions:

1) How does a μp based (Static) relay is different from electro mechanical relay?

2) What is the working principle of microprocessor based relay?

3) What is a relay? Mention few protective devices other than relay.

4) What is the significant of TMS?

5) Define pickup and drop off value of a relay?

6) Give applications of electromagnetic and microprocessor based relay.

Questions:

1) Performance the experiment on Microprocessor based Over Voltage relay for a fault

voltage setting of 105% of Vn & Normal inverse 3.5 Second trip time characteristics. Obtain

the operating characteristics these setting of the relay.

Result &Conclusion:

Signature of staff



Circuit diagram:

Schematic Diagram Relay under Test

Fig.1 Circuit Diagram

Fig.2




OPERATING CHARACTERISTICS OF NEGATIVE PHASE

SEQUENCE STATIC RELAY

AIM: To study the operation of DMT Negative phase sequence solid state Relay

Apparatus:

Sl.No. Name Quantity 1 DMT Negative phase sequence

relay & test kit

2 Induction Motor

3 Connecting Leads

Procedure

1. Connect as per diagram 3 & 4.

2. Connect Aux. power cord.

3. Connect three phase input. (415V, 3 ph )

4. Mains Switch ON.(Rocker)

5. Push CB ON button. – CB on indicator will glow.

i) CB on indicator will glow

ii) If motor connected, its starts running. Note down the ammeter readings.

(Rheostat should be in zero (cut) position.

6. Adjust the Rheostat to create the Negative sequence (Unbalance )

7. Negative sequence relay gets “ACTIVE” and “TRIP”.

8. Push “CB OFF./ RESET”.

9. Without disturbing the rheostat switch on the “CB ON” and note down the

ammeter reading and trip timing.

10. Interchange the three phase R, Y, B sequence and Observe.



Tabular Column:

Balanced Condition

SI No.

Current in

Phase R

Current in

Phase Y

Current in

Phase B

Time in Seconds

Unbalanced Condition

SI No.

Current in

Phase R

Current in

Phase Y

Current in

Phase B

Time in

Seconds



Viva questions:

1) How does a Negative phase sequence relay works?

2) What are applications of the negative phase sequence relay?

Result &Conclusion:

Signature of faculty



Circuit Diagram

CB

CT TRIP

1 P

h,2

30V

ac

TR

AN

SF

OR

ME

R

RELAY UNDER TESTF S1

S2

CI

AU

X.

VARIAC

POT.FREE CB

NO

NC

CONTROL CIRCUIT

TIME INTERVAL

METER

A

R





OPERATING CHARACTERISTICS OF MICROPROCESSORBASED

OVER CURRENT RELAY

AIM: To study the operation of microprocessor based over current relay and obtain its

operating characteristics.

Apparatus:

Sl.No. Name Quantity 1 Microprocessor based over

current relay & test kit

2 Connecting Leads

Procedure:

1) Connect as per interconnection diagram.

2) Set the relay current – (Setting procedure – refer LT MANUAL).

3) Set TMS.

4) Ensure Time interval meter selection switch in TIM position.

5) Ensure Protection time switch is ON position.

6) Connect the power card.

7) Bring dimmer to zero position.

8) Put on the mains using Mains on switch.(ROCKER). Results (Mains on

indicator, ammeter display, relay power and Timer display will glow.)

9) Bring Toggle switch ‘SET’ mode.

10) Push TEST START BUTTON, CB ON Indicator will glow.

11) Adjust the dimmer set the approximate injection current (within 30 seconds

other wise protection timer will activate and circuit breaker will be off.

12) Push TEST STOP/RESET BUTTON.

13) Don’t disturb the dimmer.



Tabular column:

TMS

Relay Current

Setting

Fault

Current(A)

PSM= fault current/ relay

current setting

Operating Time

(S)



14) Bring Toggle switch ‘TEST’ mode.

15) Push TEST START BUTTON, Note down the current. (Circuit

breaker ON, CB ON indicator will glow, time interval meter starts up

counting, Protection timer starts down counting, over current relay trip

occurs TRIP indicator will glow at relay and injector unit also. If buzzer

switch is on it gives the beep sound.

16) Note down the Time Interval Meter reading. (Pick up time)

17) Press the RESET button.

18) Repeat operation (9 – 18) by adjusting different Current & TMS settings

19) Draw the graph Trip time Vs PSM (plug setting Multiplier.)

NOTE: For finding up the pickup current, protection timer switch in by pass position and

mode switch kept at test position.

After test start gradually increase the dimmer from zero to your current set value

and when the trip indicator led starts blinking note down the pickup current.

Setting the fault current level:

Fault current level IS is expressed as percentage of CT rating ( In = 1 A ). This relay offers

three ranges of IS i.e. 10 to 40 %, 20 to 80 % & 50 to 200 % which can be set by using DIP

switches. IS can be calculated as follows:

IS = (0.1R + R ∑ a) * In

Where, IS = Set current level (fault current level) in A

In = CT rating (1A)

a = Weight of switch in ON position

R = Constant depending on the setting range as given below.

Sl.No.

Setting range

R

1 10% to 40% 1

2 20% to 80% 2

3 50% to 200% 5



Graph.1

TIME vs PSM

0.00

2.50

5.00

7.50

10.00

12.50

15.00

17.50

20.00

22.50

25.00

27.50

30.00

1 10 100

PSM

TIM

E



Time multiplier settings: This switch offers various options of trip time for a selected trip time characteristic. This can

be done by using DIP switches. Trip time T is given by formula

T = K* (0.1 +∑t)

Where K = Constant depending on trip time characteristics selected.

t = Weight of switch in ON position

Characteristics Curve to be drawn = Trip Time Vs PSM



CALCULTAION:

How to find out the PSM ( Plug setting Multiplier)

Fault Current

PSM = ---------------------------------

Plug setting

If CT used

Fault Current (primary current)

PSM = ---------------------------------------------------------------------------

Plug setting (Primary Setting Current) x CT ratio

Actual Operating time (Ta) in sec.

TSM = --------------------------------------------------------------------

Calibrated Operating Time for TSM = 1.0 (Tc) in sec

EXAMPLE:

Relay current setting is 150% ( relay 100%=5A) and has Time multiplier setting of 0.5,

the relay has connected in the circuit through a C.T. having ratio 500:5 amps 500/5A

Fault current is 6000Amps. Relay characteristics as assume for PSM 8=3.15sec at TMS is

1.

Solution:

150 % = 1.5A

5

See fault current 6000A x ----- = 60A

500

1

Plug setting multiplier PSM = 60 x ---------- = 8

5 x 1.5

Time from graph against this multiplier is 3.15sec.

Operating time = 3.15 x 0.5 = 1.575sec.

Characteristics selected Value of K

Normal inverse ( 1.3 sec ) 1.3

Normal inverse ( 3.0 sec ) 3.0

Very inverse 1.5

Extremely inverse 0.8

Definite time ( 1.0 sec ) 1.0

Definite time ( 10 sec ) 10

Definite time ( 100 sec ) 100



Result &Conclusion:




Circuit Diagram

CB

PT

V

CT

CI

VA

RIA

C-1

VA

RIA

C-2

AU

X.

TRIP1 P

h,2

30

Va

c

RELAY UNDER TEST

NC

NO

POT.

FREE

F S1

V SOURCE

P1

S1

P2

S2 CB

I SOURCE

A

CONTROL CCT.

TIME INTERVAL

METER

Fig.1 CONNECTION DIAGRAM




OPERATING CHARACTERISTICS OF MICROPROCESSOR BASED

IMPEDANCE- DISTANCE REALY

AIM: To study the operation of microprocessor based impedance relay.

Apparatus:

Sl.No Name Quantity

1 Microprocessor based impedance relay & test kit

2 Induction Motor

3 Connecting Leads

Procedure:

1. Connect power cord.

2. Set relay impedance in % (0% to 200%).

3. Set K TMS .( 10 – 100 in steps of 10 )

4. Bring both dimmer to zero position.

5. Put on the mains using Mains on MCB. Mains on indicator, ammeter display, relay

power and Timer display will glow.

6. Push “CB ON” button.

7. CB ON indicator will also glow.

8. Adjust voltage. ( 0 – 250V)

9. Adjust current (range 0 – 2A) max 1A only.

10. Presses relay start.

11. Timer will start, and if the % of impedance is less than set value relay will trip

according to the characteristics.

12. Note down the voltage, current.

13. Calculate the impedance.

14. Repeat the experiment using different voltage and current setting.



Tabular column:

Z ref = %

K =

Sl.No. %Zset Ts(Sec) Tf(Sec) TRIP TIME

Tf – Ts (Sec)

Example:

If relay is set 100% impedance. Ie voltage is 220V and current is 1A

= 220V/1A = 220Ω impedance = 100%

220

---------

1

------------- x 100 = 100%

220

Assume of the transmission line is 400km impedance is 220Ω

Impedance per km is 0.55Ω

The relay was tripped at 70% of impedance.

( 220Ω x 70%) x 100 = Z154Ω

Fault occurred at the distance of = 154 / 0.55 = 280kms.



Result &Conclusion:




Circuit diagram

RR

VR

V

V

R

V

V

V

MOTOR

PHASE REVERSAL SWITCH

Hz

1 PH

VOLT METER PF METER PHASE SEQ.INIDCAT

OR

SINGLE

PHASE

GND FAULT

Y

B

N

AMMETER

RPM METER

TEMP RELAY

OVER CURRENT

UNDER CURRENT

STALL

LOCK

EMPR

DIGITAL MOTOR PROTECTION

RELAY

CB

CT

PHASE FAILURE

REVERSE PHASE

ASYMMETRY

GROUND FAULT

U

V

W

N

E

CB

E

A

E

C

FUSEMCB

Fig.1 CIRCUIT DIAGRAM




DIGITAL MOTOR PROTECTION

RELAY STUDY UNIT

AIM: To study the operation of digital motor protection relay for various fault

conditions.

* GROUND FAULT/ EARTH LEAKAGE FAULT.

Motor, 3 HP, 3 Phase , DELTA, CG

1415 rpm, 4.8A, 415v, 50c/s.

Procedure:

1. Connect the Three phase power supply with Neutral and Ground.

2. Connect motor (Terminals provided at the top side of mimic.

3. Switch on power supply at source.

4. Switch on the MCB on the testing kit and look for power on indication (R, Y,B).

5. Trip indicator and buzzer will be ON, reset it.

6. Set the motor protection relay parameters.

Inverse /definite characteristic – definite.

Definite time – 2sec.

Reverse phase protection – ON

Under current protection – OFF

Ground fault – 0.05Sec

Stall function – ON

Lock function – ON – 200%

CT ratio - 1

Phase failure – ON

Store.

Current – 2A

7. Adjust the dimmer to 415V

8. Push Motor ON button. Insuring that there is no load on the motor and observes the

current and voltage of all the phases and records it.



TABULAR COLUMN -1 NO LOAD:

Sl,No.

MOTOR AMMETER

READING

VOLT METER Hz RPM PF TRIP TIME

R

Y

B

RY

YB

BR

1

2



PROCEDURE FOR OVER CURRENT PROTECTION:

1. Adjust the over current setting in the motor protection relay to 1.8Amps

considering that as normal load current.

2. Set the motor protection relay parameters.

i) Inverse /Definite characteristic – Definite.

ii) Definite Time – 2SEC.

iii) Reverse Phase Protection – ON

iv) Under Current Protection – OFF

v) Ground Fault – 0.05SEC

vi) Stall Function – ON

vii) Lock Function – ON – 200%

viii) CT ratio - 1

ix) Phase Failure – ON

x) Store.

xi) Current – 2.0A

3. Switch ON the ground fault switch. POSITION-2 (Don’t connect grounding

rheostat, terminal at Right side of the control panel).

4. Switch ON the motor.

5. Gradually load the motor using the dynamometer while observing the current in

Ammeter.( Note down Ammeter and timer readings when the relay operates.)

6. Relay trip occurs –

i) Motor will be Stop.

ii) Relay display shows O-L , bar graph will be Turn ON.

iii) Hooter will be ON.

iv) Fault indicator will be glow.

7. Now accept the fault by pressing the accept push button.

8. Reset the relay by pressing test/ reset button.

9. Press the Reset button at control panel.

10. Bring fault ground fault simulation switch to home position (1).

11. Again switch ON the motor and record the voltage and current etc.,

PROCEDURE FOR PHASE FAILURE PROTECTION:

1. Ensure motor is OFF.



TABULAR COLUMN – 2 OVER CURRENT PROTECTION:

TABULAR COLUMN- 3 PHASE FAILURE PROTECTION:

Sl,No.

MOTOR

AMMETER

READING

VOLT METER Hz RP

M

PF TRIP TIME

R

Y

B

RY

YB

BR

1

2

Sl,No.

MOTOR AMMETER

READING


R

Y

B

RY

YB

BR

1

2



2. Bring the all the fault simulation to position 1.

3. Switch ON fault simulation single phase.

4. Ensure the EMPR settings

a. Inverse /definite characteristic – definite.

b. Definite time – 2Sec.

c. Reverse phase protection – ON

d. Under current protection – OFF

e. Ground fault – 0.05sec

f. Stall function – ON

g. Lock function – ON – 200%

h. CT ratio - 1

i. Phase failure – ON

j. Store.

k. Current – 2A


6. Note down the timer reading.


l. Motor will be Stop.

m. Relay display shows –P-F Bar graph will be Turn ON.

n. Hooter will be on.

o. Fault indicator will be glow.




11. Bring SINGLE PHASE FAULT simulation switch to home position (1).

PROCEDURE FOR PHASE REVERSAL PROTECTION:



3. Switch ON Phase Reverse fault simulation to position 2.

4. Ensure The EMPR Settings

a. Inverse /Definite characteristic – Definite.

b. Definite time – 2Sec.




TABULAR COLUMN- 4 PHASE REVERSAL PROTECTION:

TABULAR COLUMN-5 UNDER CURRENT PROTECTION:

Sl,No.

MOTOR AMMETER

READING


R

Y

B

R

Y

YB

BR

1

2

Sl,No.

MOTOR AMMETER

READING


R

Y

B

RY

YB

BR

1

2



d. Under current protection – OFF

e. Ground fault – 0.05Sec



h. CT ratio - 1


j. Store.

k. Current – 2.0A



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.




10. Bring fault simulation switch to home position (1).

PROCEDURE FOR UNDER CURRENT PROTECTION:




a. Inverse /Definite characteristic – Definite.

b. Definite time – 2sec.


d. Under current protection – ON

e. Ground fault – 0.05Sec



h. CT ratio - 1


j. Store.

k. Current – 2.0 A



TABULAR COLUMN- 6 GROUND LEAKAGE / FAULT PROTECTION:

Sl,No..

MOTOR AMMETER

READING

VOLT METER Hz RPM PF LEAKAGE

CURRENT

TRIP

TIME

R

Y

B

RY

YB

BR

1

2




5. Adjust the load 4.0 A.

6. EMPR bar graph will read 100%

7. Reduce the load less than 70% of bar graph.


Motor will be Stop.

Relay display shows –Und, Bar graph will be Turn ON.

Hooter will be ON.

Fault indicator will be glow.




12. For measuring the trip time. (Switch ON the ground fault switch. POSITION-2

(Don’t connect grounding rheostat, terminal at Right side of the control panel).

13. Without disturbing settings again switch on the motor and note down the readings.

GROUND LEAKAGE / FAULT PROTECTION:



3. Short the rheostat terminal using patch cord or to measure the leakage current use

Rheostat more than 2k value.


Inverse /Definite characteristic – Definite.

Definite time – 2 Sec.

Reverse phase protection – ON

Under current protection – ON

Ground fault – 0.05Sec



TABULAR COLUMN- 7 STALL PROTECTION

Sl,No.

MOTOR

AMMETER

READING

VOLT METER Hz RP

M

PF TRIP TIME

R

Y

B

RY

YB

BR

1

2



Stall function – ON

Lock function – ON – 200%

CT ratio - 1

Phase failure – ON

Store.

Current – 2.0 A

5. Switch on the motor.

6. Adjust the rheostat till motor trips. (Factory set is 100mA sensitive current).


a. Motor will be Stop.

b. relay display shows –g-F, bar graph will be Turn ON.

c. Hooter will be ON.

d. Fault indicator will be glow.


9. Reset the EMPR and panel.

10. Switch on the motor.

11. Record the data’s.


13. Press the Reset button at control panel & timer.

14. Bring fault simulation switch to home position (1).

15. Remove the rheostat connection.

PROCEDURE FOR STALL PROTECTION:

For stall protection set the motor current 2.0A and disables the lock protection.

Set it definite mode

Switch on the motor and load it just above the 180% of set current. EMPR will shows the

fault stall.

PROCEDURE FOR LOCK PROTECTION

For LOCK protection set the motor current 2.0A and disables the STALL protection.

At inverse mode



TABUALR COLUMN-8 LOCK PROTECTION:

Repeat the above experiments with INVERSE characteristics also.

TABULAR COLUMN- 9 OVER VOLTAGE/UNDER VOLTAGE:

TABULAR COLUMN- 10 NEGATIVE PH.SEQ.CURRENT PROTECTIONS:

Sl,No.

MOTOR AMMETER

READING


R

Y

B

RY

YB

BR

1

2

Sl,No.

MOTOR AMMETER

READING


R

Y

B

RY

YB

BR

1

2

Sl,No.

MOTOR AMMETER

READING


R

Y

B

RY

YB

BR

1

2



Switch on the motor and load it just above the 200% of set current. EMPR will show the

fault LOCK

Procedure for Over Voltage / Under Voltage Protection



3. Set voltage settings in UV /OV relay

a. Press the prog button few seconds,

b. Using cursor key.

c. Select the characteristic IDMT or Definite.

4. Press the start button of the relay

5. Reduce / increase according to the relay mode i.e. OV/UV

6. According to the trip time characteristics relay will be tripped.

PROCEDURE FOR NEGATIVE PHASE SEQUENCE CURRENRT RELAY



3. Set voltage all the phase voltages are equal

4. Release the motor load.


6. Slightly reduce the any one of the phase voltage using dimmer

7. Observe the relay active LED starts glowing.

8. According to the relay characteristics relay will trip.

For finding out the phase reversal

At EMPR switch off the protection of reverse phase and change the input phases.

PROCEDURE FOR POWER FACTOR CORRECTION



3. Set voltage all the phase voltages are equal

4. Release the motor load.

5. Start the motor

6. Load the motor ~5A

7. Switch ON the capacitor bank switch pos1 and pos2 note down the readings.



TABULAR COLUMN- 11 POWER FACTOR CORRECTION:

Sl,No.

MOTOR AMMETER

READING


R Y B RY YB BR

1

2



Result &Conclusion:




Connection Diagram

CB

CI

CT

CT

CI

VA

RIA

C-1

VA

RIA

C-2

AU

X.

TRIP1 P

h,2

30

Va

c

RELAY UNDER TEST

NC

NO

POT.

FREE

F S1

A1

PRI.

S1

S1

S2

S2 CB

SEC.

A2

CONTROL CCT.

TIME INTERVAL

METER





STATIC % DIFFERENTIAL RELAY

Aim: To study the characteristics of static % differential relay

Procedure:


2. Set the relay % RELAY AT 50% using selector switch. (20, 30, 40 &50%)

3. Set TMS (knob) maximum position.

4. Connect power cord.

5. Set relay % setting. (20%, 30%, 40% and 50%).

6. Bring the both the dimmer to zero position.

7. Put on the mains using Mains on switch.(rocker). Results (Mains on indicator,


8. Put Mode selector switch in the ‘SET’ position.


10. Set the current using dimmer PRIMARY and note down the current. ( I1) (Don’t apply

the current more than 2 A).

11. Adjust the Dimmer 2 current equal to the I1

12. Then gradually decrease the current I2, when the relay active led starts glowing note

down the I2 current. (Don’t apply the current more than 2 A).

13. Observe I1 = I2 relay will not active. If the difference is less than or greater than the %

of set value relay gets active.

14. Set the I1=I2 and reset the relay, repeat the operation (10-14) by adjusting the different

% setting, different current settings of I1 and I2 and draw the graph.

15. Draw the graph I1-I2 vs ( I1+I2)/2

Procedure: For finding Inverse characteristics

1. Put Mode selector switch in the ‘SET’ position.

2. Bring the both the dimmer to zero position.

3. Set relay % setting. (20%, 30%, 40% and 50%).

4. Set TMS (knob) maximum position.




Tabular Column:

% selected: 50%

Sl.No.

I1

I2

I1-I2=X

(I1+I2)/2=Y

%

(X/Y) x100

1 1.0

2 0.9

3 0.8

4

5

6

7

Graph.1 characteristic of static % differential relay

(I1+I2)/2

I1-I

2



6. Set the current using dimmer PRIMARY and note down the current. ( I1) (Don’t

apply the current more than 2 A). eg.1Amp.

7. Adjust the Dimmer 2 current equal to the I1

8. Adjust the dimmer 2 I2 current (relay55% level).

9. Push TEST STOP/RESET.

10. Reset relay.

11. Don’t disturb the dimmers

12. Put Mode selector switch in the ‘TEST’ position.


14. Note down the Time Interval Meter reading.

15. Set the different 60% etc., and precede the (8-15) note down the timer reading

and draw graph or observe.

Viva questions:

1. Explain the working of static % differential relay.

2. Explain the characteristics of static % differential relay.

3. Give the application of Static % Differential relay.

4. What are the advantages of High voltage AC transmission?

Result & Conclusion:




Circuit Diagram:

L

N

C1MEMORY

PUSH

R

CT

V

C1

C1

OILTESTCELL

DOOR INTERLOCK

L OFF

ON

'O' LOCK

HV LIMIT

TRIPRL

HVLIMTI UNIT

READYMAINSON

H.TON

H.TOFF

C1C1

C1230 V

SUPPLY

FUSE

MAINSON

SWITCH

A

U

T

O

T

R

A

N

S

F

O

R

M

E

R

H

V

T

R

F





BREAKDOWN STRENGTH OF TRANSFORMER OIL

AIM: To determine the breakdown strength of given sample of transformer oil

Apparatus:

Sl. No Name Quantity

1 Transformer 60 kV, 0.5 Kva

2 Oil testing kit

3 Transformer oil

4 Transformer oil test cell

PROCEDURE:

1. Adjust the electrodes in the oil test cup for the required gap and lock it in position with

the help of screws provided.

2. Fill 80% of the cup with oil to be tested and place the cup on the HV transformer

bushings.

3. Close the top door, switch on the mains & bring the variable transformer to zero

position by means of switch provided for the reverse and forward of a auto –variable

transformer. When it comes to zero position unit ready indicators will glow. And press

‘HT’ push button, HT ON indicator will glow.

4. Increase the voltage to the required level. Voltmeter will indicate the output voltage. In

case of break-down HV will get disconnected. By pressing ‘MEMORY’ push button

read the level of break down voltage.



Observations & Calculations:

Tabulation:

Test No. Breakdown

voltage (kV) RMS

Average

Breakdown

voltage (kV)

Breakdown

Strength

kV/cm



Viva questions:

1) State Paschen’s law and draw a typical paschen’s curve and mention BDV min and

corresponding pressure for air medium.

2) What are the salient features of Townsend’s theory and streamer theory of gaseous

insulation breakdown?

3) What is the accepted value of dielectric strength of transformer oil?

4) What are the insulating media and how they are classified?

5) What is primary ionization and secondary ionization process?

Questions:

1) Conduct a suitable experiment to determine the dielectric strength of give transformer oil.

Result &Conclusion:




Circuit Diagram:

Expected Graph:



Experiment No: 10 Date:

4. SPARK OVER CHARCTERSTICS OF AIR INSULATION FOR HVAC

(CORRECTED TO STP)

Aim:

To conduct an experiment to draw spark over characteristics of air insulation

Subjected to high voltage AC with spark over voltage corrected to STP

Apparatus:

SL.

No

Name of the apparatus Range Quantity

1 High Voltage testing

Transformer

230V / 50kV, 20kVA,

0.4 Amp (Continuous) 01

2 Autotransformer 3-Φ,400V, 50Hz 01

3 Spheres 100mm Diameter 02

Procedure:

1. Connections are made as shown in the circuit.

2. By ensuring the proper grounding and autotransformer at zero position

with sphere gap set to a value, power supply is switched ON.

3. Gradually the voltage is applied across the gap between the spheres until

the spark over occurs between the spheres.

4. Note down the corresponding voltage at which the spark over occurred and

the autotransformer is brought back to initial position.

5. For same gap distance between the spheres step (3) and (4) are

repeated and three corresponding spark over voltages are noted and

tabulated.

6. Above procedure is repeated for different gaps between the spheres.

7. Spark over characteristics between gap (along X-axis) and BdvIS

(Corrected) and Bdv (STP) corrected (along Y-axis).



Tabular Column:

Calculation:

δ (air density factor)= [0.289* P (pressure)] / 273+ TDRY

δ=K1(correction factor)

IS (corrected) = IS (STP)* K1

BDV STP (Corrected) = BDV(Peak) / K1

Gap (mm)

BDV (kV)

Avg of BDV

(kV)

BDV(Peak)= BDV(avg)*√2

(kv)

BDV at STP(IS)

(kV)

BDV

IS(corrected)

(kV)

BDV

STP

(Corrected)

(kV)

5 16.8

10 31.7

15 45.5

20 59.0



Observation:

TDRY (Temp) = _______oC

P (pressure) = _______ in milibar

Relative humidity (h) = ____%

Viva questions :

1) Mention the order of voltage that is designated as HV, EHV and UHV?

2) What are the advantages of transmitting electrical power at higher voltages?

3) State the merits of HVDC transmission. Mention few HVDC projects in India.

4) Mention few apparatus employing high voltage?

5) What is difference between a conventional and HV capacitor?

6) What is the need for generating high voltages in a laboratory?

7) Why the HV termination of HV transformer is structured as a spherical one?

8) Mention the correction factors that need to be applied for HV measurement and

Explain how they are applied.

Questions:

1) Obtain the break down voltage V/s gap distance characteristics in air under application

of HVAC Sphere-Sphere electrode configuration

Result &Conclusion:




Circuit Diagram:

1. Circuit for Uniform field configuration (Sphere-sphere)

2. Circuit for Non uniform field configuration (Point-plane)



Experiment 11: date:

SPARKOVER CHARCTERSTICS OF AIR INSULATION FOR HVAC (For Uniform and No uniform field configuration)

Aim:

To conduct an experiment to draw the spark over characteristics of air

insulation subjected to high voltage AC for uniform and non uniform field

configuration

Apparatus:

Sl.No Name of the apparatus Range Quantity


Transformer

230V / 50kV, 20kVA,




4 Plane Electrode --- 01

5. Point Electrode --- 01

Procedure:

1. Connections are made as shown in the circuit with sphere-sphere

configuration for uniform field.




the spark over occurs between the spheres

4. Note down the corresponding voltage at which the spark over occurred

and the autotransformer is brought back to initial position.


6. Now Sphere- sphere electrodes arrangement is replaced by point-plane

electrodes arrangement.

7. Steps 2,3,4 and 5 are repeated for different gaps between point-plane

electrodes



Expected Graph

Tabular Column:

1. For uniform field Configuration (Sphere-Sphere)

2. For Non uniform field configuration (Point-plane)

Sl.No Gap in

mm

Break down Voltage

(kV)

1 5

2 10

3 15

4. 20

Sl.No Gap in

mm

Break down Voltage

(kV)

1 5

2 10

3 15

4. 20



8. Spark over characteristics are plotted between Gap in mm(along x-axis)

and breakdown voltage in kV(Along y-axis) and for uniform field

configuration(Sphere-sphere) and Non uniform filed configuration(point-

plane)

Results and Conclusion:




Circuit Diagram:

Expected Graph:



Experiment 12: Date:

MEASUREMENT OF HVAC USING STANDARD SPHERES

Aim:

To conduct an experiment for measuring high voltage AC using standard spheres

Apparatus:



Transformer

230V / 50kV, 20kVA,




Procedure:








5. For same gap distance between the spheres step (3) and (4) are repeated

for three times and corresponding three spark over voltages are noted

and tabulated.


7. Spark over characteristics between gap in mm (along X-axis) and BdvIS

(Corrected) and Bdv (STP) corrected in kV (along Y-axis).



Tabular Column:

Calculation:




%Error= [BDV IS (corrected) - BDV (Peak)] * 100 / BDV IS (corrected)

Gap

in

mm

BDV

(kV)

Avg of

BDV

(kV)

BDV(Peak)=

BDV(avg)*√2

(kv)

BDV at

STP(IS)

(kV)

BDV

IS(corrected)

(kV)

% Error

5 16.8

10 31.7

15 45.5

20 59.0



Observation:




Result and Conclusion:




Circuit Diagram:

Expected Graph:



Experiment: 13 Date:

SPARKOVER CHARCTERSTICS OF AIR INSULATION FOR HVDC (CORRECTED TO STP)

Aim:

To conduct an experiment to draw spark over characteristics of air insulation

Subjected to high voltage DC with spark over voltage corrected to STP

Apparatus:



Transformer

230V / 70kV, 20kVA,






6. Diode Rectifier 75kV 01

7. Resisters 150kΩ, 15kΩ 01 each

8. Capacitor 0.1µF 01

Procedure:









and three corresponding spark over voltages are noted and tabulated.


7. Spark over characteristics between gap (along X-axis) and BdvIS

(Corrected) and Bdv (STP) corrected (along Y-axis).



Tabular Column:

Calculation:




Gap (mm)

BDV(Peak) (kV)

Avg of BDV(Peak)

(kV)

BDV at STP(IS)

(kV)

BDV IS(corrected)

(kV)

BDV STP (Corrected)

(kV)

5 16.8

10 31.7

15 45.5

20 59.0



Observation:








Circuit diagram:

Expected Graph:



Experiment: 14 Date:

MEASUREMENT OF HVDC USING STANDARD SPHERES

Aim:

To conduct an experiment for measuring high voltage DC using standard spheres

Apparatus:



Transformer

230V / 70kV, 20kVA,






6. Diode Rectifier 75kV 01

7. Resisters 150kΩ, 15kΩ 01 each

8. Capacitor 0.1µF 01

Procedure:









for three times and corresponding three sparks over voltages are noted

and tabulated.


7. Spark over characteristics between gap in mm (along X-axis) and BdvIS

(Corrected) and Bdv (STP) corrected in kV (along Y-axis).



Tabular Column:

Calculation:




%Error= [BDV IS (corrected) - BDV (Peak)] * 100 / BDV IS (corrected)

Gap (mm)

BDV(Peak) (kV)

Avg of BDV(Peak)

(kV)

BDV at STP(IS)

(kV)

BDV IS(corrected)

(kV)

%Error

5 16.8

10 31.7

15 45.5

20 59.0



Observation:








Circuit Diagram




Experiment 15: Date

Spark over characteristics of air insulation subjected to high voltage

impulse using Impulse generator

AIM: To study the spark over characteristics of air insulation subjected to high voltage

impulse.

Apparatus:

Sl.No. Name Quantity Range

1 Impulse generator set up

2 Power supply

3 Earthing rod

Procedure:

1. Check all the connections and grounding properly.

2. Open the emergency switch and switch on the control panel with the help of the

Mains ON push button.

3. Bring the dimmer to zero position.

4. Bring the sphere gap to zero position and set the gap of spheres with the help of the

“sphere gap increase” and “sphere gap decrease” push button.

5. Open the earth with the help of “earth open” push button till to earth open.

6. Select the polarity with the help of “polarity” selector switch.

7. Press the HT ON switches as a result “HT ON’ indicator will glow.

8. Charge the capacitor little less than the required level by increasing the DIMMER by

manually.

9. Trigger the generator with the help of TRIGGER switch and see that flashover occurs

in all the stages at a time if not adjust the gap distance and voltage.

10. Note down the flash over voltage/ breakdown voltage.

11. After testing press the Mains OFF switch, press the emergency button and ground all

the capacitors with the help of grounding rod.



Tabular column:

SL.NO GAP DISTANCE(mm) BREAK DOWN VOLTAGE(kv)



Viva questions:

1. What is the functionality of impulse generator?

2. Define the following ,

a) Wave shaping resistors

b) Wave front time

c) Wave tail time

d) Impulse voltage

3. What is the application of impulse generator?

Questions:

1. Observe spark over characteristics of air insulation subjected to high voltage impulse

through oscilloscope

Result & Conclusion:




HV LAB QUESTIONS

Note: Each student has to do any one of the experiments given below in the examination

individually.

1) Conduct a suitable experiment to plot the graph of Trip Time vs. PSM or operating

characteristics of over current relay(electromechanical)

2) Conduct a suitable experiment to plot the graph of Trip Time vs. % of closing voltage.

3) Conduct a suitable experiment to obtain the operating characteristics of

Microprocessor based over current relay.


Microprocessor based over voltage and under voltage relay for normal inverse 3 sec.


Microprocessor based over voltage and under voltage relay for normal inverse 5 sec.


Microprocessor based over voltage and under voltage relay for definite time 10 sec.

7) Conduct a suitable experiment to obtain the graph of I1-I2 VS (I1+12)/2 using static

percentage differential relay.

8) Conduct a suitable experiment for balanced and un balanced conditions of

solid state negative phase sequence current relay.


Microprocessor based over current relay.

10) Conduct a suitable experiment for Microprocessor based impendence

distance relay for Z=80%& K=20.

11) Conduct a suitable experiment to simulate no load , phase failure ,phase

reversal and ground fault protection for digital motor .

12) Conduct a suitable experiment to measure HVAC using standard spheres for spark

over characteristics of air insulation subjected to high voltage AC/ high voltage DC, with

spark over Voltage corrected to STP for uniform and non-uniform field configuration.

13) Conduct a suitable experiment to measure HVDC using standard spheres for spark

over characteristics of air insulation subjected to high voltage AC/ high voltage DC,

with spark over Voltage corrected to STP for uniform and non-uniform field

configuration.



Question Bank:

1. What are the advantages of High voltage AC transmission? 2. What is the working principle of an electromagnetic relay?

3. What is the working principle of microprocessor based relay?

4. What are the differences between electromagnetic and microprocessor based

relay? 5. Define pickup and drop off value of a relay?

6. Give applications of electromagnetic and microprocessor based relay.

7. What are the insulating media and how they are classified? 8. What is primary ionization and secondary ionization process?

9. Differentiate between uniform and Non uniform fields.

10. What are the techniques used for High voltage measurement? 11. What are the advantages of High voltage AC transmission?

12. What is thermal breakdown?

13. What are factors which influence the measurement of High voltage using

Spheres? 14. What is source loading and how it is avoided in high voltage measurement?

15. What is the working principle of Generating voltmeter?

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Hv Manual