19EET601 - Protection and Switchgear

Which of the following results in a symmetrical fault?

• single phase to earth

• phase to phase

• all the three phases to earth

• two phases to earth

Which portion of the power system is more prone to faults?

• Alternator

• overhead lines

• underground cables

• transformer

Most dangerous type of fault on any power system is:

• Phase to earth

• Phase to Phase

• Phase to Phase to Earth

• Three phase fault

In the protection scheme, relay functions as a.....

• switching device

• isolating device

• breaking device

• sensing device

The unprotected zone in the power system is called as……..

• hot spot

• live spot

• dead spot

• zone spot

Which one of the following is not an essential quality of a relay?

• Accuracy

• Sensitivity

• Reliability

• Fast Operation

Transformers are protected by ……….protection.

• over current

• differential

• distance

• carrier current

Purpose of back up protection is to

• increase the speed

• increase a reach

• leave no blind spot

• guard against failure of primary

Over current protection responds to….

• increase in current above pick up value

• single line to earth faults

• double line to earth faults

• three phase faults

In the R-X plane, the characteristics of an impedance relay is represented by a

• parabola

• circle

• straight line

• square