Protection and SWitchgear

Numerical relays are useful for

• protection

• measurement and storing

• control

• all of the above

GPS stands for

• Group Protection Services

• General Protection Services

• Geographical Positioning System

• none of the above

The correct statement about Buchholz relay

• It can only be used with largely sized alternators

• It is installed with largely sized transformers which have no conservator tank

• It can detect incipient faults

• It should never be used with oil immersed transformers

Buchholz relay is used to protect:

• ALTERNATOR

• INDUCTION MOTOR

• SYNCHRONOUS MOTOR

• TRANSFORMER

Plug setting multiplier is defined as the ratio of:

• Fault current in relay coil x Pick up current

• Fault current in relay coil / Pick up current

• Fault current in relay coil x Transformer secondary turns

• Fault current in relay coil / Transformer secondary turns

The basic purpose of a relay is to:

• Detect the fault

• Remove the fault

• Trip the circuit

• All of these

Backup protection is installed to:

• Increase the protection reliability of the system

• To increase the speed of protection system

• Both of these

• None of these

The current transformer can also be used to measured high d.c. current.

• true

• false

The main function of a fuse is to

Protect the line

Open the circuit

Prevent excessive currents

None of the above

True or False?

Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream

• True

• False