Electrical Studys

1] A fuse in a motor circuit provides protection against

1 pointA. OverloadB. Short-circuit and overloadC. Open circuit, short-circuit and overloadD. None of the above

2] A short-circuit is identified by

1 pointA. No current flowB. Heavy current flowC. Voltage dropD. Voltage rise

3] In a single bus-bar system there will be complete shut down when

1 pointA. Fault occurs on the bus itselfB. Fault occurs on neutral lineC. Two or more faults occur simultaneouslyD. Fault occurs with respect to earthing

4] The inductive interference between power and communication line can be minimized by

1 pointA. Transposition of the power lineB. Transposition of the communication lineC. Both (A) and (B)D. Increasing the distance between the conductors

5] Over voltage protection is recommended for

1 pointA. Hydroelectric generatorsB. Steam turbine generatorsC. Gas turbine generatorsD. All of the above

6] Series reactors should have

1 pointA. Low resistanceB. High resistanceC. Low impedanceD. High impedance

7] _________ relays are used for phase faults on long line.

1 pointA. ImpedanceB. ReactanceC. Either of the aboveD. None of the above

8] Induction cup relay is operated due to changes in

1 pointA. CurrentB. VoltageC. ImpedanceD. All of the above

9] For the protection of power station buildings against direct strokes the requirements are

1 pointA. InterceptionB. Interception and conductionC. Interception, conduction and dissipationD. Interception, conduction, dissipation and reflection

10] The time of closing the cycle, in modern circuit breakers is

1 pointA. 0.003 secB. 0.001 secC. 0.01 secD. 0.10 sec

11] Interruption of large currents by relay requires

1 pointA. Arc suppressing blow out coilsB. Wide separation of the opened contactsC. High speed opening of contactsD. All of the above

12] Burden of a protective relay is the power

1 pointA. Required to operate the circuit breakerB. Absorbed by the circuit of relayC. Developed by the relay circuitD. None of the above

13] Overload relays are of _________ type.

1 pointA. InductionB. Solid stateC. ThermalD. All above

14] On which of the following routine tests are conducted?

1 pointA. Oil circuit breakersB. Air blast circuit breakersC. Minimum oil circuit breakersD. All of the above

15] A balanced 3-phase system consists of

1 pointA. Zero sequence currents onlyB. Positive sequence currents onlyC. Negative and zero sequence currentsD. Zero, negative and positive sequence currents

16] Protection by fuses is generally not used beyond

1 pointA. 20 AB. 50 AC. 100 AD. 200 A

17] The torque produced in induction type relay (shaded pole structure) is

1 pointA. Inversely proportional to the currentB. Inversely proportional to the square of the currentC. Proportional to the currentD. Proportional to square of the current

18] What will be the reflection coefficient of the wave of load connected to transmission line if surge impedance of the line is equal to load?

1 pointA. ZeroB. UnityC. InfinityD. None of the above

19] The relay with inverse time characteristic will operate within

1 pointA. 1.5 secB. 5 to 10 secC. 5 to 20 secD. 20 to 30 sec

20] The short circuit in any winding of the transformer is the result of

1 pointA. Mechanical vibrationB. Insulation failureC. Loose connectionD. Impulse voltage

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