J D College Of Engineering & Management, Nagpur

(Diploma)

Course Name : Electrical Engineering, Course Code : EE, Semester : Fifth

Subject :Switchgear and Protection, Subject Code : 22524 Date: - / /2024
Question Banks for Winter-2024

Unit 1 –Basics of protection

1. State four functions of protective system. (2 marks)
2. Define Reliability and Sensitivity. (2 marks)
3. Write essential features of good protective system. (2 marks)
4. Write any eight causes of fault occurrence in the power system.(6marks)
5. State any four abnormal conditions in power system (4marks)
6. State the need of back-up protection where it is used. . (2 marks)
7. With the help of suitable diagram explain the concept of protection zones. (4marks)
8. What is reactor? Classify reactors on the basis of their location(4marks)
9. State importance of feeder reactor. Write any two disadvantages of it(4marks)
10. List different types of faults occurred on a power system. Draw necessary sketches (4marks)
11. Draw symbol of following: i) Earth Switch ii) Lightning arrester iii)Circuit breaker iv) Isolator
(4marks)
12. A plant consists of two 10 MVA generators of reactance 18% each and two 5 MVA generators of
12% each. All are connected to bus bar to supply a load through three step up transformers of 8
MVA each having reactance of 8%. Determine fault MVA on HV side of transformer. (6 marks)
13. Calculate fault MVA at point F as shown in Figure No. 1. (6 marks)
Unit 2 –Circuit interrupting devices
1. Define isolator and state their types (2 Marks)
2. Explain working of vertical break isolator with neat sketch(4 Marks)
3. Compare ACB and MCB(4 Marks)
4. Distinguish between C.B. and Isolator( 4 Marks)
5. Define terms related to circuit breaker: (4 Marks)
i) Making capacity
ii) Breaking capacity
iii) Short time Rating
iv) Normal current Rating
6. Compare SF6 and vacuum circuit breaker on the basis of arcing time, recovery voltage, fault
clearing time and RRRV. (4 Marks)
7. List any four applications of HRC fuse. ( 4 Marks)
8. Describe the construction of SF6 circuit breaker with neat diagram and state any four properties of
SF6 gas(6 Marks)
9. State function of RCBO and MPCB. ( 4 Marks)
10. Explain construction of H.R.C. Fuse. ( 4 Marks)
11. Draw the construction diagram of ELCB and explain how ELCB gives protection against earth
leakage fault. (4 Marks)
12. State the comparison on any four points between Air insulated and Gas insulated switchgear.
( 4 Marks)
13. State any two factors for the selection of LT CB. (2 Marks)
14. Draw and explain a neat circuit diagram of vacuum circuit breaker. State any two advantages of it.
(4 Marks)
15. Explain arcing phenomenon in circuit breaker and state methods of arc extinction. (4 Marks)
16. Give any two advantages of SF6 C.B. (2 Marks)
17. Define: - arc voltage, restriking voltage, recovery voltage and RRRV(4 Marks)
18. With the help of neat diagram explain arc extinction phenomenon for high resistance current
interruption(4 Marks)
19. State the specification of CT and PT as protective transformers(4 Marks)
20. Related to vacuum circuit breaker) (6 Marks)
i) i ) Draw neat sketch
ii) Write any four importance points related to its construction.
iii) Give any two advantages and two disadvantages
Unit 3-protective relays
1. Describe any six fundamental quality requirements of protective relaying.( 4 Marks)
2. Define Plug setting multiplier and Time setting multiplier. .( 2 Marks)
3. State the need of directional relay .( 2 Marks)
4. Define – Relay time, reset current, pick-up current, current setting.( 4 Marks)
5. Draw neat circuit diagram of solenoid type relay .( 4 Marks)
6. With the help of suitable diagram explain the working of Thermal relay. .( 4 Marks)
7. With neat sketch explain watt-hr. meter structure of induction type relay. .(4 Marks)
8. Draw and explain operation of induction type direction of Directional over current relay. .( 6 Marks)
9. With the help of block diagram explain operation of Micro- processor based over current
protection.(6 Marks)
10. With the help of neat sketch explain time/current characteristic of over current relay.( 6 Marks)
11. Explain the principle of time graded protection of feeders using IDMT over current relays.
(6 Marks)
12. Draw a block diagram of microprocessor based over current protection. State function of each
block.(6 Marks)
13. Explain with neat sketch basic trip circuit of protection relaying.( 4 Marks)
14. Explain with a neat sketch the operation of attracted armature type relay. Also give its two merits
and demerits.( 6 Marks)
15. With the help of neat diagram, explain operation of static relay. .(4 Marks)

Unit 4 –protection of alternator and transformer

1. Write any eight different fault occurs in alternator.( 4 Marks)
2. List any four protection scheme used for alternator.( 4 Marks)
3. Explain reverse power protection of 3Φ alternator.(4 Marks)
4. With neat sketch explain working of restricted earth fault protection scheme of transformer.
( 4 Marks)
5. List any four faults occurred in transformer.( 4 Marks)
6. Describe the operation of current differential relay with neat sketch . .( 4 Marks)
7. Explain the “Differential Protection Scheme” used for alternators with neat .( 4 Marks)
labeled diagram.
16. Describe the construction and Operation of Buchholz relay with neat labeled diagram. .( 6 Marks)
17. Draw neat sketch of percentage differential protection of a transformer. .(4 Marks)

Unit 5 –Protection of Motors, busbars,and transmission lines

1. List any four faults related to busbar.(4 Marks)
2. List any four major faults related to 3Φ IM. Draw sketch of single phasing preventer. .(4 Marks)
3. Explain short circuit protection of 3Φ IM. .(4 Marks)
4. Discuss in brief the principle of distance protection and state four advantages of Distance
protection scheme. .(4 Marks)
5. Explain the working of single phasing preventer with neat diagram. .(4 Marks)
6. Explain with neat sketch, the Pilot wire protection scheme applied to
7. transmission line. .(4 Marks)
8. Explain with neat sketch working principle of distance relay(4 Marks)
9. Explain with neat sketch differential protection scheme of bus bar(4 Marks)

------------------------------------------All the Best-------------------------------------------