30+Electrical question and Answers

1➤ In case of transmission line protection, overcurrent relay is used .

Only up to 220 kVOnly up to 50 kVOnly up to 1100 kVOnly up to 110 kV

2➤ As the spacing between the phase conductors increases, the line resistance

DecreasesBecomes infinityIncreasesRemains same

3➤ The currents fed into pilots from each end should be same for

Normal conditionAbnormal conditionFault conditionAll of the options

4➤ Inrush currents having more harmonic content give more ________ and relay does not operate

Harmonic blockingRestraining torqueRestrain differential relayAll of the options

5➤ The CB which has high reliability and less maintenance is .

Bulk oilAir blastSF6Minimum oil

6➤ Isolators used in transmission line are capable of breaking

No currentLoad currentCharging currentFault current

7➤ When the conductors of three phase transmission line are not spaced equilaterally, the transposition is done to

Reducing the unbalancing effect of the irregular or unsymmetrical spacing.For better appearanceMinimizing the effect of adjoining communication circuits. Decrease the line inductance

8➤ External heating, baking and revarnishing of insulation are the methods of----------of insulation.

DryingFilteringNone of the optionscleaning

9➤ A basic push-pull amplifier optimally

Reduces odd horminics in the outputReduces even horminics in the outputAmplify the currentOperates as the input stage of audio amplifier

10➤ The hot-wire ammeter

is a high precision instrumentis used only for AC circuits reads equally well on DC and / or AC circuitsis used only for DC circuits

11➤ Bulbs in street lighting are all connected in

ParallelSeries-parallelEnd-to-endSeries

12➤ The internal causes of failure of transformer includes ------ .

a phase to ground faultshort circuit fault in the windingtemperature rise above permissible limit for longer timeAll of the options

13➤ ADLS is ---------------

Switching the motor to star mode when the load is greater than 40 percent.When the load increases beyond 40 percent it switches the motor to operatein delta mode;it is automatic star to delta converterAll of the optionsAutomatic delta to star converter

14➤ burglar alarm circuit, which type of sensor is used? Ans 1. 2. 3. 4.

Pressure sensorHumidity sensorThermal sensor Photo sensor

15➤ Which of the following is NOT one of the advantages of tidal power generation?

It is completely independent of the precipitation and its uncertainty, besides being inexhaustible.It is free from pollutionLarge area of valuable land is not requiredAs compared to other sources of energy, this is economical

16➤ Single phase full-wave controlled rectifier is also called:

one quadrant converterdouble SCR rectifiertwo quadrant converterone SCR rectifier

17➤ Which of the following motors are used in machine tools?

Slip ring induction motorsPipe ventilated type motors Squirrel-cage motorsD.C. cumulative motors

18➤ __________ have frequency band range 20 kHz - 30 MHz.

Video frequency oscillatorsRadio frequency oscillatorsHigh frequency oscillatorsVery high frequency oscillators

19➤ ________ is one of the type of electrical dust collectors from steam power plants.

Spray type.Cyclone separatorsPacked typeRod type.

20➤ Which of the following methods of starting is required for induction motors of high rating?

Rotor resistance startersAuto-transformer startersStart delta starters Direct on line starters

21➤ Which of the following is NOT necessary to be checked while maintaining cross arms of lines?.

Creeper on cross armsRusting of cross armsTilting of cross armsSinking of earth around the pole

22➤ Which of the following in NOT the correct point to be considered in designing a good lightning scheme?

The intensity of illumination required.The size of the room. The temperature of the roomThe selection of the required lamp and fitting.

23➤ ________ is NOT one of the types of a 'digital voltmeter'

Potentiometric type DVMStatic balance type DVMRamp type DVM Integrating type DVM

24➤ The generator whose field magnet winding is supplied from an independent external DC source is called:

compounded separate DC generatorindividual shunt DC generatorseparately excited DC generatorseries-shunt DC generator

25➤ Which of the following instruments use the Hall effect?

Flux metersWatt metersIntegrating metersVoltmeters

26➤ The mechanical heart of a diesel engine is the _______.

exhaust systemair intake systemfuel injection systemengine starting system

27➤ Air-break circuit breakers are used in DC. circuits and AC circuits ___________, where air at atmospheric pressure is used.

for 33 kV and abovefor 220 kV and aboveabove 760 kVup to 12 kV

28➤ A 1000 Hz sinusoidal voltage is connected to both X and Y input of the CRO, then the waveform displayed on CRO screen is

Straight LineCircleSine WaveEllipse

29➤ synchronous motor connected to the bus bar running at no load condition the air gap flux was found to be 20 mWb. When the motor is disconnected from the supply the air gap flux founded to be 25 mWb. Then the no load power factor of the motor is

LaggingLeadingZero power factor laggingUPF

30➤ The relay used for phase fault protection of short transmission line is .

Reactance relayMho relayISMT relay Impedance relay

31➤ The rating of the circuit breaker is usually determined on the basis of ____________ fault.

Double line to groundSingle line to groundLine to line 3 ph Symmetrical

32➤ Supplementary tests are required to be performed --------- .

on some of the machines manufactured in a lot of same designwhen additional information is required in respect of particular machine either by manufacturer or by purchaseron each and every machine manufactured in an industryAll of the options

33➤ Basic relay connection requirement is that the relay must operate for

rated load.internal as well as external faults. internal faults.any abnormal condition

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