Switch Gear And Protection Set 5

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This set of Switch Gear and Protection Multiple Choice Questions & Answers (MCQs) focuses on Switch Gear And Protection Set 5

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.