Switchgear protections Archives

21. Directional relays are based on flow of

power

current

voltage wave

all of the above

Detailed SolutionDirectional relays are based on flow of

22. The inverse definite mean time relays are used for over current and earth fault protection of transformer against

heavy loads

internal short-circuits

external short-circuits

all of the above

Detailed SolutionThe inverse definite mean time relays are used for over current and earth fault protection of transformer against

23. Overheating of relay contacts or contact born out is due to

slow making and breaking of load circuit contacts

foreign matter on the contact surface

too low contact pressure

all of the above

Detailed SolutionOverheating of relay contacts or contact born out is due to

24. The short circuit in any winding of the transformer is the result of

mechanical vibration

insulation failure

loose connection

impulse voltage

Detailed SolutionThe short circuit in any winding of the transformer is the result of

25. A balanced 3-phase system consists of

zero sequence currents only

positive sequence currents only

negative and zero sequence currents

zero, negative and positive sequence currents

Detailed SolutionA balanced 3-phase system consists of

26. Protective relays are devices that detect abnormal conditions in electrical circuits by measuring

current during abnormal condition

voltage during abnormal condition

constantly the electrical quantities which differ during normal and abnormal conditions

none of the above

Detailed SolutionProtective relays are devices that detect abnormal conditions in electrical circuits by measuring

27. On which of the following routine tests are conducted ?

Oil circuit breakers

Air blast circuit breakers

Minimum oil circuit breakers

All of the above

Detailed SolutionOn which of the following routine tests are conducted ?

28. Which of the following parameter can be neglected for a short line?

Inductance

Capacitance

Resistance

Reactance

Detailed SolutionWhich of the following parameter can be neglected for a short line?

29. For the protection of power station buildings against direct strokes the requirements are

interception

interception and conduction

interception, conduction and dissipation

interception, conduction, dissipation and reflection E. none of the above

Detailed SolutionFor the protection of power station buildings against direct strokes the requirements are

30. If the fault occurs near the impedance relay, the VII ratio will be

constant for all distances

lower than that of if fault occurs away from the relay

higher than that of if fault occurs away from the relay

none of the above

Detailed SolutionIf the fault occurs near the impedance relay, the VII ratio will be

Page 1 Page 2 Page 3 Page 4 Page 5

Test 1 Test 2

Exit mobile version