400 Important Switchgear and Protection MCQ Question and Answer | PDF Free Download
1.A distance relay with inherent directional property is known as
- ABuchholtz relay
- BAdmittance relay
- CDirectional over current relay
- DDirectional switched relay
2.A distance relay is said to be inherently Directional if its characteristics on R-X diagram
- AIs a straight line off-set from the origin.
- BIs a circle that passes through the origin.
- CIs circles that enclose the origin.
- DAlways a separate directional relay is required.
3.For the protection of lines against faults involving variable fault resistance, the preferred relaying scheme is a
- APlain impedance relay
- BDirectional overcurrent relay
- CMho relay
- DReactance relay
4.The relay used for phase fault protection of short transmission lines is
- AReactance relay
- BImpedance relay
- CMho relay
- DIDMT relay
5.Mho relay is usually employed for the protection of
- AShort lines only
- BMedium lines only
- CLong lines only
- DAny line
6.Where severe synchronising swing occur, the relay employed is
- AImpedance relay
- BMho relay
- CReactance relay
- DInduction relay
7.Which of the following relays has inherent directional characteristic?
- AMho
- BReactance
- CImpedance
- DNone of the above
8.A differential relay response to
- AAlgebraic difference of two or more similar electrical quantities.
- BPhasor difference of two or more similar electrical quantities.
- CAlgebraic difference between two currents.
- DAlgebraic difference between two voltages.
9.Difference relays are used for protection of equipment against
- AInternal faults
- BOvercurrent
- CReverse current
- DReverse power
10.Undervoltage relays are mainly used for
- AMotor protection
- BTransformer protection
- CGenerators
- DAll of these
11.In a biased differential relay the bias is defined as a ratio of
- ANumber of turns of restraining and operating coil.
- BOperating coil current and restraining coil current.
- CFault current and Operating coil current.
- DFault current and Restraining coil current.
12.Differential relays are used for protection of
- AFeeders
- BAlternators
- CTransformers
- DAll of these
13.Both voltage and current signals are required for
- AA plain overcurrent relay
- BA differential relay
- CA directional relay
- DA biased differential relay
14.The relay used for feeder protection is
- AUndervoltage relay
- BTranslay relay
- CThermal relay
- DBuchholz relay
15.In the case of transmission line protection, overcurrent relay is used
- AOnly up to 110 kV.
- BOnly up to 220 kV.
- COnly up to 50 kV.
- DOnly up to 1,100 kV.
16.Phase relays are used to provide protection against
- ASingle line to ground fault.
- BThree phase fault only.
- CPhase faults involving two or more phases.
- DDouble phase to ground fault only.
17.Zero-sequence current is used for relaying purposes only in the case of
- APhase overcurrent relay.
- BPhase impedance relay.
- CGround overcurrent relay.
- DGround impedance relay.
18.The transistor relays have the advantages Over conventional electromechanical relays are
- ALow power consumption, less maintenance and greater sensitivity.
- BQuick operation and high reset to pick-up ratio.
- CWide range of characteristics approaching more or less to ideal requirements.
- DAll of the above.
19.The transistor relays have the limitations Over conventional electromechanical relays are
- ACharacteristics varying temperature and ageing.
- BLow short-time overload capacity.
- CReliability dependent upon the large number of small components and their electrical connections.
- DAll of the above.
20.In a static overcurrent relay, inverse time characteristics are obtained by
- AA transistor amplifier.
- BAn integrating circuit.
- CA transistor switch.
- DA differentiating circuit.