# Dr. A.P.J. Abdul Kalam University BE VI SEM (EX) Switchgear & Protection [EX-601] June 2021 Question Paper

Dr. A.P.J. Abdul Kalam University

Bachelor of Engineering

Sixth Semester Examination, June-2021

Switchgear & Protection [EX-601]

Branch- EX

Time: 3:00 Hrs Max Marks 70

Note : 1. Attempt any five questions.

2. All question carry equal marks.

3. Answer should be precise & to be point only.

4. Assume suitable data if necessary & state them clearly.

Q.1 (a) Describe different types of symmetrical & unsymmetrical faults in power

systems.

(b) Draw and explain single line and equivalent impedance diagram of power

system components.

Q.2 (a) Define per unit impedance with a suitable example.

(b) What is current limiting reactors and what are its applications?

Q.3 (a) Define relay. Explain primary and backup protection of relay.

(b) Explain the concept of pickup, reset & drop-off ratio, drop off/ pick up ratio.

Q.4 (a) Explain R-X diagram in detail.

(b) Explain working principle and characteristics of IDMT relay.

Q.5 (a) What do you understand by impedance, mho & reactance relay with R-X

diagram?

(b) Describe static analog & digital relays.

Q.6 (a) What is elementary principle of arc quenching? Define recovery and

restriking voltage

(b) Explain operation of SF6 circuit breaker and write its advantages.

Q.7 (a) What do you understand by lightning and also discuss over voltage due to

lightning?

(b) What are lightning arrestors?

Q.8 Write short note (any three)

(i) Over Current Relay

(ii) Over Voltage Relay

(iii) Directional Relay

(iv) Differential Relay

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