400 Important Switchgear and Protection MCQ Question and Answer | PDF Free Download
1.Resistance switching is normally employed in
- ABulk oil circuit breaker
- BMinimum oil breaker
- CAir-blast circuit breaker
- DAll types of circuit breaker
2.The air-blast circuit breakers for 400 kV system are designed to operate in
- A0.1 s
- B0.5 s
- C50 Ms
- D100 Ms
3.The minimum oil circuit breaker has less volume of oil because
- AThe oil between the breaker contacts has greater strength.
- BThere is insulation between the breaker contacts.
- CSolid insulation is provided for insulating the contacts from the earth.
- DNone of the above.
4.While using air-blast circuit breaker, current chopping is a phenomenon often observed when
- AA long overhead line is switched off.
- BA bank of capacitor is switched off.
- CA transformer on no load is switched off.
- DA heavy load is switched off.
5.Resistance switching is used In air-blast circuit breaker to
- AReduce the magnitude of fault current.
- BControl the CB operating time.
- CDamp out the fast transient.
- DCharge the fault current power factor.
6.Sulphur hexafluoride circuit breakers have the drawback(s) of
- ASealing problem of gas.
- BIngress of moisture in the gas system-dangerous.
- CDeterioration of SF6 with time.
- DBoth (a) and (b)
7.The single most important property that makes Sulphur hexafluoride a very efficient medium for circuit breaking is
- AIt is non-toxic and non-inflammable.
- BIt has high dielectric constant.
- CIt has high breakdown strength.
- DIt is highly electronegative in character.
8.Air used in air blast circuit breaker must
- ABe ionized.
- BBe free from moisture.
- CHave least Carbon Dioxide
- DHave oil mist.
9.Sulphur hexafluoride gas is transported in
- AAir cylinders.
- BGas cylinders.
- CLiquid form in cylinders.
- DSolid form.
10.The current chopping tendency is minimised by using Sulphur hexafluoride gas at relatively
- ALow pressure and high viscosity.
- BLow pressure and Low viscosity.
- CHigh pressure and Low viscosity.
- DHigh pressure and high viscosity.
11.To limit current chopping in vacuum circuit breakers, the contact material employed should have the properties of
- ALow conductivity and High vapour pressure.
- BLow conductivity and Low vapour pressure.
- CHigh conductivity and High vapour pressure.
- DHigh conductivity and Low vapour pressure.
12.A thermal protection switch provides protection against
- AOverload
- BTemperature
- CShort circuit
- DOvervoltage
13.For remote operation, the circuit breaker must be equipped with
- AInverse time trip
- BShunt trip
- CTime delay trip
- DAll of these
14.Which of the following circuit breakers is generally used in railway electrification?
- AAir-blast circuit breaker
- BMinimum oil circuit breaker
- CBulk oil circuit breaker
- DSulphur hexafluoride circuit breaker
15.The preferred circuit breaker to be installed for extra-high voltage AC system is
- ABulk oil type CB
- BAir-blast CB
- CVacuum CB
- DSulphur hexafluoride CB
16.Keeping in view the cost and overall effectiveness, the following circuit breaker is best suited for capacitor bank switching
- AVacuum
- BAir-blast
- CSulphur hexafluoride
- DOil
17.Which of the following circuit breakers has the lowest voltage range?
- ASulphur hexafluoride circuit breaker
- BAir-blast circuit breaker
- CTank type oil circuit breaker
- DAir-break circuit breaker
18.Which of the following circuit breakers produce the least arc energy?
- APlain oil
- BMinimum oil
- CAir-blast
- DAir break
19.Which of the following circuit breakers has high reliability and negligible maintenance?
- AAir-blast
- BSulphur hexafluoride
- COil
- DVacuum
20.Which of the following circuit breakers take minimum time in installation?
- AAir-blast
- BMinimum oil
- CBulk oil
- DSulphur hexafluoride