Important question

EE6702 Protection and Switchgear Important questions Regulation 2013 Anna University

EE6702 Protection and Switchgear Important questions

EE6702 Protection and Switchgear Important questions Regulation 2013 Anna University free download. EE6702 Important questions Protection and Switchgear pdf free download.

Sample EE6702 Protection and Switchgear Important questions:

1. What are the functions of protective relays

To detect the fault and initiate the operation of the circuit breaker to isolate the
defective element from the rest of the system, thereby protecting the system from damages consequent to the fault.

2. Give the consequences of short circuit. (EE6702 Protection and Switchgear Important questions)

Whenever a short-circuit occurs, the current flowing through the coil increases to an enormous value. If protective relays are present , a heavy current also flows through the relay coil, causing it to operate by closing its contacts.The trip circuit is then closed , thecircuit breaker opens and the fault is isolated from the rest of the system. Also, a low voltage may be created which may damage systems connected to the supply.

3. Define protected zone. ()

Are those which are directly protected by a protective system such as relays, fuses or switchgears.If a fault occurring in a zone can be immediately detected and or isolated by a protection scheme dedicated to that particular zone.

4. What are unit system and non unit system? (EE6702 Protection and Switchgear Important questions)

A unit protective system is one in which only faults occurring within its protected
zone are isolated.Faults occurring elsewhere in the system have no influence on the operation of a unit system.A non unit system is a protective system which is activated even when the faults are external to its protected zone.

5. What is primary protection?

Is the protection in which the fault occurring in a line will be cleared by its own
relay and circuit breaker.It serves as the first line of defence.

6. What is back up protection? (EE6702 Protection and Switchgear Important questions)

Is the second line of defence , which operates if the primary protection fails to
activate within a definite time delay.

7. Name the different kinds of over current relays.

Induction type non-directional over current relay,Induction type directional over current relay & current differential relay.

8. Define energizing quantity.

It refers to the current or voltage which is used to activate the relay into operation.

9. Define operating time of a relay. (EE6702 Protection and Switchgear Important questions)

It is defined as the time period extendind from the occurrence of the fault through
the relay detecting the fault to the operation of the relay.

10. Define resetting time of a relay.

It is defined as the time taken by the relay from the instant of isolating the fault to
the moment when the fault is removed and the relay can be reset.

EE6702 Protection and Switchgear Important questions

Subject Name Protection and Switchgear
Subject Code EE6702
Regulation 2013

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