Switch Gear And Protection Set 3 MCQs

Q1 | The line insulation is the insulation level of the station equipment.

less than

same as

more than

not directly related with

Q2 | The interaction between a transmission line and communication lineis 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

Q3 | When a wave propagates on a transmission line, it suffers reflection several times at

tapping

load end

sending end

sending and other end

Q4 | 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

Q5 | Discrimination between main and back up protection is provided bythe use of relays which are

fact

sensitive

slow

none of the above

Q6 | Induction cup relay is operated due to changes in

current

voltage

impedance

all of the above

Q7 | 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

Q8 | 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 reactance

Q9 | Short-circuit currents are due to

single phase to ground faults

phase to phase faults

two phase to ground faults

any of these

Q10 | To reduce short circuit fault currents are used.

reactors

resistors

capacitors

none of the above

Q11 | Bus coupler is very essential in arrangement

single bus

double bus, double breaker

main and transfer bus

all of the above

Q12 | For cost and safety, the outdoor substations are installed for voltagesabove

11 kV

33 kV

60kV

110kV

Q13 | The short circuit in any winding of the transformer is the result of

mechanical vibration

insulation failure

loose connection

impulse voltage

Q14 | relays are used for phase faults on long line.

Impedance

Reactance

Either of the above

None of the above

Q15 | For which of the following protection from negative sequencecurrents is provided?

Generators

Motors

Transmission line

Tr

Q16 | relay is preferred for phase fault on short transmission line.

Induction type

Reactance

Impedance

None of the above

Q17 | Distance relays are generally

split-phase relays

reactance relays

impedance relays

none of the above

Q18 | For which of the following ratings of the transformer differentialprotection is recommended ?

above 30 kVA.

equal to and above 5 MVA

equal to and above 25 MVA

none of the above

Q19 | A _______ is used to measure the stator % winding temperature ofthe generator.

thermocouple

pyrometer

resistance thermometer

thermometer

Q20 | The under voltage relay can be used for

generators

busbars

transformers

all of the above

Q21 | The relay with inverse time characteristic will operate within

1.5 sec

5 to 10 sec

5 to 20 sec

20 to 30 sec

Q22 | 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

Q23 | Which of the following devices will receive voltage surge firsttravelling on the transmission line ?

Lightning arresters

Relays

Step-down transformer

Switchgear

Q24 | Which of the following parameter can be neglected for a short line ?

Inductance

Capacitance

Resistance

Reactance

Q25 | Series reactors should have

low resistance

high resistance

low impedance

high impedance