MCQ on Control and Protection 3

1. For the protection of stator winding of an alternate against internal fault involving ground the relay used is a:

A. Biased differential relay
B. Directional over-current relay
C. Plain impedance relay
D. Buchholz relay

2. The least expensive protection for over current in low-voltage system is:

A. Rewirable fuse
B. Isolator
C. Circuit breaker
D. Air-break switch

3. Buchholz relay is used for protection of:

A. Busbar
B. Transformer
C. Alternator
D. Motors

4.Outdoor switchgear is generally used for voltage beyond:

A. 11 KV
B. 33 KV
C. 66 KV
D. 132 KV

5. The operating speed of a relay depends upon the:

A. Rate of flux built up
B. Armature core air gap
C. Spring tension
D. All of these

6. Inverse time current relays are used for the protection of

A. Feeders
B. Transformers
C. Alternators
D. Both A and B

7. For the protection of a very long extra high-voltage lines, the productive relay used is:

A. Over currently with extremely inverse characteristics
B. Percentage differential relay
C. Reactance type distance relay
D. Mho type distance relay

8.A bus-bar is rated by

A. Current only
B. Voltage only
C. Current , voltage and frequency
D. Current, voltage, frequency and short circuit current

9. The material used for bus-bar should have

A. Low resistivity
B. Low-cost
C. High Softening temperature
D. All of the above

10.Which of the following bus-bar schemes has the lowest cost?

A. Ring bus-bar scheme
B. Single bus-bar scheme
C. Breaker and a half scheme
D. Main and transfer scheme

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