Q.1 The main function of a fuse is to
(a) Protect the line .
(b) Open the circuit .
(c) Protect the appliance .
(d) Prevent excessive currents.✔️
Q.2 Arc in a circuit breaker is interrupted at
(a) Zero current.✔️
(b) Maximum current .
(c) Minimum voltage
(d) Maximum voltage
Q. 3 Induction cup relay operates when there is changes in
(A) voltage.
(B) current.
(C) impedance.
(D) all of the above.✔️
Q.4 The arcing contacts in a circuit breaker are generally made of
(A) lead tin alloy.
(B) copper tungsten alloy.✔️
(C) electrolytic copper.
(D) aluminium alloy.
Q.5 On which of the following routine tests are conducted ?
(a) Oil circuit breakers.
(b) Air blast circuit breakers.
(c) Minimum oil circuit breaker .
(d) All of above ✔️
Q.6 SF6 Gas
(a) Yellow in colour.
(b) Lighter then air.
(c) Nontoxic .✔️
(d) None of above.
Q.7 The operating time of fuse is nearly
(a) 1 Second.
(b) .5 Second.
(c) 0.002 Second.✔️
(d) 1.5 Second.
Q.8 Operating time of circuit breaker is
(a) 0.02 Second.
(b) 0.2 Second.✔️
(c) 1 Second .
(d) 1.4 Second.
Q.9 The arcing contact in circuit breaker are made of
(a) Copper tungsten alloy.✔️
(b) Electrolytic copper.
(c) Alluminium alloy.
(d)Porcelain
Q. 10 Which of the following medium is employed for extinction of arc in air circuit breaker?
(a) SF6
(b) Air✔️
(c) Oil
(d) water
Q.11 IDMT relays are used to protect the power transformer against
(a) Overload .
(b) Internal short circuit .
(c) External short circuit .
(d) External short circuit and over load .✔️
Q.12 Which of the folowing relay is used for the generator phase to phase winding protection
(a) Mho relay .
(b) Distance realy.
(c) Voltage balance relay.
(d) Differential relay. ✔️
Q.13 Which of the following circuit breaker must be equiped for remote operation
(a) Inverse time trip.
(b) Shunt trip.✔️
(c) Time delay trip.
(d) All of above .
Q.14 Fault diverter are basically
(a) Relay.
(b) Fuse.
(c) Fast switch.✔️
(d) Circuit breaker .
Q.15 A thermal protection switch can protect against
(a) Short circuit .
(b) Temperature .
(c) Over voltage .
(d) Over load.✔️
Q16 Art in a circuit breaker behaves as
(a) An inductive reactance .
(b) A resistance increasein with voltage rise across the arc .
(c) A resistance decreasing with voltage rise across arc.✔️
(d) Inductive reactance .
Q.17 thermal circuit breaker has
(a) Delay trip action.✔️
(b) Instantaneous trip action.
(c) Both of above .
(d) None of above .
Q.18 Realy can be designed to respond change in
(a). Temperature
(b) Voltage an current.
(c) Resistance impedance reactance .
(c) All of above .
Q.19 Over load realy are of
(a) Induction and electromagnetic type
(b) Solid state type.
(c) Thermal type.
(d) all of above ✔️
Q.20 Which of following relay is used to detect and protect internal fault of a transformer.
(a) Differential realy.
(b) Bucholoz realy.✔️
(c) IDMT .
(c) Directional relay.
Q.21 Which of following relay is used for anti- motoring protection scheme
(a) Reactance relay.
(b) Reverse relay.✔️
(c) Differential relay.
(d) Moh relay.
Q.22 Resistance switching is normally employed in
(a) Bulk oil breakers.
(b) Minimum oil breaker.
(c) Air blast circuit breaker .✔️
(d) SF6 circuit breaker.
Q.23 In overload system the relay used for feeder protection is
(a) Under voltage relay.
(b) IDMT realy.
(c)Thermal relay.
(d) Translay relay.✔️
Q.24. Magnetic circuit breaker has trip action is
(a) Delayed.
(b) Instantaneous.✔️
(c) None of above.
(d) All of above.
Q.25 DC shunt relays are made of
(a) Few turns of thin wire .
(b) Few turns of thick wire.
(c) Many turns of thin wire .✔️
(d) Many turns of thick wire .
Q.26 The relay Operating speed depends on
(a) The spring tension.
(b) The rate of flux built up.
(c) Armature core air gap
(d) All of above ✔️
Q.27 The arc voltage in a circuit breaker is
(a) in the phase with arc current..✔️
(b) lagging the arc current by 90°.
(c) leading the arc current by 90°.
(d) lagging the arc current by 180°.
Q.28 What is the reactive power in AC operation?
(a) Real power × sinφ.
(b) Apparent power × sinφ.✔️
(c) Real power × cosφ.
(d) Apparent power × cosφ.
Q.29 The purpose of using series capacitor in a transmission lines is to
(a) reduce inductance.
(b) reduce line losses.
(c) compensate voltage drop.✔️
(d) improve power factor.
Q.30 Which of the following circuit breaker is design for the least operating voltage?
(a) Vacuum circuit breaker.
(b) Air circuit breaker.✔️
(c) SF6 circuit breaker.
(d) Oil circuit breaker.
Q.31 The rating of a circuit breaker is usually determine on the basis of
(a) symmetrical fault.✔️
(b) unsymmetrical fault.
(c) line to line fault.
(d) internal fault.
Q. 32 Circuit breakers are usualy operate under
(a) Transient state of short circuit current.✔️
(b) Sub transient state of short circuit current .
(c) Steady state of short circuit current .
(d) All of above
Q.33 Circuit breaker are essentially
(a) Current carring contact called electrod.✔️
(b) Arc extinguishers.
(c) circuit to break the system .
(c)All of above.
Q. 34 Air blast circuit breaker is used for
(a) Over current .
(b) Short duty .
(c) Intermediate duty.
(d) Repeated duty.✔️
Q.35 Directional relay are based on folow of
(a) Current.✔️
(b) Power.
(c) Voltage .
(d) All of above.
Q.36. A differential relay measures the vector difference between
(a) Two current.
(b) Two Voltage .
(c) Two or more similar electrical quantities.✔️
(d) None of above
Q. 37 A transmission line is protected by
(a) Inrush protection.
(b) Distance protection
(c) Both a and b✔️
(d) None of above .
Q.38 Large internal fault are protected by
(a) Merz price percentage differential protection.✔️
(b) Mho relay
(c) Ohms relay
(d) none of above
Q.39 Chimney effect occurs in
(a) Sf6 circuit breaker .
(b) Vacuum circuit breaker .
(c) Oil circuit breaker.
(d) Air blast circuit breaker .✔️
Q.40 The arc voltage in a ac circuit breaker is
(a) in phase opposition with the arc current .
(b) In phase with arc current ✔️
(c) Lag arc current by 90°
(d) Lead arc current by 90°
Q.41 Electrical Switchgear is consider as low voltage Switchgear if it is rated upto
(a) 400 V.
(b) 1 kV.✔️
(c) 11 kV.
(d) 33kV.
Q.42 Under normal condition, the voltage across a lighting arrestor is
(a) zero.
(b) very small.
(c) equal to phase voltage.
(d) equal to line voltage✔️
Q.43. Generally, the circuit breakers are rated term of
(a) volt-ampere.
(b) current.
(c) voltage.✔️
(d) VAR.
Q.44 Which device is used to protect the power system against traveling waves?
(a) capacitor.
(b) earth wire.
(c) surge diverter.✔️
(d) earthing screen.
Q.45 In the electric system, Resonance may result in
(a) zero voltage.
(b) high voltage.✔️
(c) low voltage.
(d) high current.
Q.46 A device which is used to protect an electric circuit from damage caused by over load or short circuit is
(a) Wave trapper.
(b) CVT.
(c) circuit breaker.✔️
(d) lighting arrester.
Q 47 Ionization in circuit breaker is facilitated by
(a) High temperature .
(b) Increase of mean free path.
(c) Increasing field strength.
(d) all of above ✔️
Q.48 shunt capacitance is neglected while considering
(a) Short transmission line .✔️
(b) Medium transmission line
(c) Long transmission line
(d) Long and midium transmission line .
Q.49 Insulation resistance of high voltage circuit breaker is more then
(a) 10 mega ohms.
(b) 1 mega Ohms.
(c) 100 mega ohms .✔️
(d) 500 mega ohms.
Q.50 HRC fuse provide best protection against
(a) Over load .
(b) Reverse current .
(c) Open circuit.
(d) Short circuit. ✔️
