Testing And Commissioning Of Electrical Equipment’S Set 3 MCQs

Q1 | Which of the following statements is incorrect?

Station batteries are used to operate relay only

The lightning arresters are basically surge diverters

An impedance relay has maximum fault current when fault occurs near the relay

A high speed relay has an operation of 1 to 2 cycles

Q2 | Discrimination between main and back up protection is provided by the use ofrelays which are

fact

sensitive

slow

none of the above

Q3 | Induction cup relay is operated due to changes in

current

voltage

impedance

all of the above

Q4 | A.C. network analyser is used to solve problems of

load flow

load flow and short-circuit

load flow and stability

load flow, short-circuit and stability

Q5 | Which of the following statements is incorrect ?

Lightning arrestors are used before the switchgear

Shunt reactors are used as compensation reactors

The peak short current is (1.8 xV2) times the A.C. component

The MVA at fault is equal to base MVA divided by per unit equivalent fault

Q6 | To reduce short circuit fault currents are used.

reactors

resistors

capacitors

none of the above

Q7 | Bus coupler is very essential in arrangement

single bus

double bus, double breaker

main and transfer bus

all of the above

Q8 | For cost and safety, the outdoor substations are installed for voltages above

11 kV

33 kV

60kV

110kV

Q9 | The short circuit in any winding of the transformer is the result of

mechanical vibration

insulation failure

loose connection

impulse voltage

Q10 | relays are used for phase faults on long line.

Impedance

Reactance

Either of the above

None of the above

Q11 | For which of the following protection from negative sequence currents is provided ?

Generators

Motors

Transmission line

Transformers

Q12 | relay is preferred for phase fault on short transmission line.

Induction type

Reactance

Impedance

None of the above

Q13 | Distance relays are generally

split-phase relays

reactance relays

impedance relays

none of the above

Q14 | For which of the following ratings of the transformer differential protection is recommended ?

above 30 kVA.

equal to and above 5 MVA

equal to and above 25 MVA

none of the above

Q15 | A _______ is used to measure the stator % winding temperature of the generator.

thermocouple

pyrometer

resistance thermometer

thermometer

Q16 | The relay with inverse time characteristic will operate within

1.5 sec

5 to 10 sec

5 to 20 sec

20 to 30 sec

Q17 | The single phasing relays are used for the protection of

single phase motors only

two phase motors only

two single phase motors running in parallel

three phase motors

Q18 | Which of the following devices will receive voltage surge first travelling on thetransmission line ?

Lightning arresters

Relays

Step-down transformer

Switchgear

Q19 | Which of the following parameter can be neglected for a short line ?

Inductance

Capacitance

Resistance

Reactance

Q20 | Series reactors should have

low resistance

high resistance

low impedance

high impedance

Q21 | Which of the following circuit breakers has high reliability and minimummaintenance ?

Air blast circuit breakers

Circuit breaker with SF6 gas

Vacuum circuit breakers

Oil circuit breakers

Q22 | Arc in a circuit breaker is interrupted at

zero current

maximum current

minimum voltage

maximum voltage

Q23 | transmission line has reflection coefficient as one.

Open circuit

Short-circuit

Long

None of the above

Q24 | What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ?

Zero

Unity

Infinity

None of the above

Q25 | 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