Testing And Commissioning Of Electrical Equipment’S Set 2 MCQs

Q1 | When a transmission line is energized, the wave that propagates on it is

current wave only

voltage wave only

both (A) and (B)

power factor wave only

Q2 | 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

Q3 | The voltage appearing across the contacts after opening of the circuit breaker iscalled______voltage.

recovery

surge

operating

arc

Q4 | Ionization in circuit breaker is facilitated by

high temperature

increase of mean free path

increasing field strength

all of the above

Q5 | In a circuit breaker the basic problem is to

maintain the arc

extinguish the arc

transmit large power

emit the ionizing electrons

Q6 | 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

Q7 | Interruption of large currents by relay requires

arc suppressing blow out coils

wide separation of the opened contacts

high speed opening of contacts

all of the above

Q8 | Shunt capacitance is neglected while considering

short transmission line

medium transmission line

long transmission line

medium and long transmission lines

Q9 | The arc voltage produced in A.C. circuit breaker is always

in phase with the arc current

lagging the arc current by 90?

leading the arc current by 90°

none of the above

Q10 | The time of closing the cycle, in modern circuit breakers is

0.003 sec

0.001 sec

0.01 sec

0.10 sec

Q11 | Insulation resistance of high voltage circuit breakers is more than

1 mega ohms

10 mega ohms

100 mega ohms

500 mega ohms

Q12 | H.R.C. fuses provide best protection against

overload

reverse current

open-circuits

short-circuits

Q13 | The ground wire should not be smaller than No ______ copper.

2

4

6

10

Q14 | The delay fuses are used for the protection of ________.

motors

power outlet circuits

fluorescent lamps

light circuits

Q15 | Which of the following is the least expensive protection for overcurrent is lowvoltage system ?

Rewireable fuse

Isolator

Oil circuit breaker

Air break circuit breaker

Q16 | Resistance grounding is used for voltage between

33kVto66kV

HkVto33kV

3.3kVandllkV

none of the above

Q17 | The contacts of high voltage switches used in power system are submerged in oil.The main purpose of the oil is to

lubricate the contacts

insulate the contacts from switch body

extinguish the arc

all of the above

Q18 | In Railway applications ______ circuit breaker is used.

SFe

bulk oil

minimum oil

air break

Q19 | To protect most of the electrical equipment handling low power, the types of relaysused are

thermocouple

electronic and bimetallic

both (A) and (B)

none of the above

Q20 | Wave trap is used to trap waves of

power frequencies

higher frequencies entering generator or transformer units

either of the above

none of the above

Q21 | Ungrounded neutral transmission system is not recommended because of system

insulation being overstressed due to over voltages

insulation overstress may lead to failure and subsequent phase to phase faults

being inadequately protected against ground fault

all of the above

Q22 | The reflection co-efficient at the open circuited end of a transmission line.

zero

infinity

unity

none of the above

Q23 | For the protection of power station buildings against direct strokes the requirementsare

interception

interception and conduction

interception, conduction and dissipation

interception, conduction, dissipation and reflection

Q24 | The interaction between a transmission line and communication line is minimized by

transposing transmission as well as communication lines

increasing the height of the trans-mission line tower

increasing the distance between the two lines

all of the above

Q25 | When a wave propagates on a transmission line, it suffers reflection several times at

tapping

load end

sending end

sending and other end