Switch Gear And Protection Set 5 MCQs

Q1 | Oil switches are employed for

low currents circuits

low voltages circuits

high voltages and large currents circuits

all circuits

Q2 | A switchgear is device used for

interrupting an electrical circuit

switching an electrical circuit 111.

switching and controlling an electrical circuit

switching, controlling and protecting the electrical circuit and equipment

Q3 | The fuse wire, in D.C. circuits, is inserted in

negative circuit only

positive circuit only

both (a) and (b)

either (a) or (b)

Q4 | By which of the following methods major portion of the heatgenerated in a H.R.C. fuse is dissipated ?

Radiation

Convection

Conduction

All of the above

Q5 | A short-circuit is identified by

no current flow

heavy current flow

voltage drop

voltage rise

Q6 | The information to the circuit breaker under fault conditions isprovided by

relay

rewirable fuse

H.R.C. only

all of the above

Q7 | To limit short-circuit current in a power system are used.

earth wires

isolators

H.R.C. fuses

reactors

Q8 | A balanced 3-phase system consists of

zero sequence currents only

positive sequence currents only

negative and zero sequence currents

zero, negative and positive sequence currents

Q9 | In a single bus-bar system there will be complete shut down when

fault occurs on the bus itself

fault occurs on neutral line

two or more faults occur simultaneously

fault occurs with respect to earthing

Q10 | Which device is used for protection of equipment from from damagecaused by overload or short circuit?

CVT

Circuit Breaker

Current Transformer

Lighting Arrester

Q11 | Isolator in substation is open under ------------- condition?

No load

Short Circuit

Full Load

Any of the above

Q12 | Earthling switch is used for

measuring of safety voltage

protection of equipment from ground faults

discharging residual energies

all of the above

Q13 | If the time of operating of a relay for unity TMS is 10secs., the time ofoperation for 0.5 TMS will be

20 secs.

5 secs.

10 secs.

None of the above

Q14 | A fault is more severe from the view point of RRRV if is a

Short line fault.

Medium length line fault.

Long line fault.

None of these.

Q15 | A reactance relay is

Voltage restrained directional relay.

Directional restrained over-current relay.

Voltage restrained over-current relay.

None of the above.

Q16 | For measuring positive, negative and zero sequence voltages in asystem, the reference is taken as

Neutral of the system only.

Ground only.

For zero sequence neutral and for positive and negative the ground.

None of the above.

Q17 | Positive, negative and zero sequence impedances of a solidly grounded system under steady state condition always follow the relations

Z4>Z2>Z0

Z2>Z4>Z0

Z0>Z4>Z2

None of the above

Q18 | Phase comparators in case of static relays and electro-mechanical relaysnormally are

Sine and cosine comparators respectively

Cosine and sine comparators respectively.

Both are cosine comparators.

Both are sing comparators.

Q19 | For reducing tower footing resistance it is better to use

Chemical and ground rods only.

Chemical and counterpoise only.

Ground rod and counterpoise only.

Chemical, ground rods and counterpoise.

Q20 | Rate of rise of restriking voltage depends

Type of circuit breaker.

Inductance of the system only.

Capacitance of the system only.

Inductance and capacitance of the system

Q21 | What is the purpose of back up protection?

To increase the speed

To increase the reach

To leave no blind spot

To guard against failure of primary

Q22 | What is the actuating quantity for the relays?

Magnitude

Frequency

Phase angle

All of these

Q23 | Protective relays can be designed to respond to

Light intensity, impedance

Temperature, resistance, reactance

Voltage and current

All of these

Q24 | On what factor does the operating speed of the relay depend upon?

Rate of flux built up

Armature core air gap

spring tension

All of these

Q25 | What does the third part consist of?

Primary winding of a current CT which is connected in series with the line to be protected.

Secondary of the CT and the operating coil.

Tripping circuit.

All of these.