Switch Gear And Protection Set 1 MCQs

Q1 | The main function of a fuse is to

protect the line

open the circuit

protect the appliance

prevent excessive currents

Q2 | On which of the following routine tests are conducted?

Oil circuit breakers

Air blast circuit breakers

Minimum oil circuit breakers

All of the above

Q3 | SF6 gas

is yellow in colour

is lighter than air

is nontoxic

has pungent small

Q4 | The arcing contacts in a circuit breaker are made of

copper tungsten alloy

porcelain

electrolytic copper

aluminium alloy

Q5 | Which of the following medium is employed for extinction of arc in aircircuit breaker ?

Water

Oil

Air

SF6

Q6 | With which of the following, a circuit breaker must be equipped for remote operation ?

Inverse time trip

Time-delay trip

Shunt trip

None of the above

Q7 | Fault diverters are basically

fuses

relays

fast switches

circuit breakers

Q8 | A thermal protection switch can protect against

short-circuit

temperature

overload

over voltage

Q9 | Arc in a circuit behaves as

a capackive reactance

an inductive reactance

a resistance increasing with voltage rise across the arc

a resistance decreasing with voltage rise across the arc

Q10 | Thermal circuit breaker has

delayed trip action

instantaneous trip action

both of the above

none of the above

Q11 | Relays can be designed to respond to changes in

resistance, reactance or impedance

voltage and current

light intensity

all above

Q12 | Overload relays are of…… type.

induction

solid state

thermal

all above

Q13 | Thermal overload relays are used to protect the motor against overcurrent due to

short-circuits

heavy loads

grounds

all of the above

Q14 | Magnetic circuit breaker has ______ trip action.

delayed

instantaneous

both of the above

none of the above

Q15 | D.C. shunt relays are made of

few turns of thin wire

few turns of thick wire

many turns of thin wire

many turns of thick wire

Q16 | The relay operating speed depends upon

the spring tension

the rate of flux built up

armature core air gap

all of the above

Q17 | In order that current should flow without causing excessive heating orvoltage drop, the relay contacts should

have low contact resistance

be clean and smooth

be of sufficient size and proper shape

have all above properties

Q18 | Circuit breakers usually operate under

transient state of short-circuit current

sub-transient state of short-circuit current

steady state of short-circuit current

after D.C. component has ceased

Q19 | Circuit breakers are essentially

current carrying contacts called electrodes

arc extinguishers

circuits to break the system

tr

Q20 | The current zero interruption, in oil and air blast circuit breakers, is achieved by

lengthening of the gap

cooling and blast effect

both (a) and (b)

deionizing the oil with forced air

Q21 | Air blast circuit breaker is used for

over currents

short duty

intermittant duty

repeated duty

Q22 | An efficient and a well designed protective relaying should have

good selectivity and reliability

economy and simplicity

high speed and selectivity

all of the above

Q23 | Burden of a protective relay is the power

required to operate the circuit breaker

absorbed by the circuit of relay

developed by the relay circuit

none of the above

Q24 | Directional relays are based on flow of

power

current

voltage wave

all of the above

Q25 | A differential relay measures the vector difference between

two currents

two voltages

two or more similar electrical quantities

none of the above