Testing And Commissioning Of Electrical Equipment’S Set 3

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This set of Testing and Commissioning of Electrical Equipment’s Multiple Choice Questions & Answers (MCQs) focuses on Testing And Commissioning Of Electrical Equipment’S Set 3

Q1 | Which of the following statements is incorrect?
  • Station batteries are used to operate relay only
  • The lightning arresters are basically surge diverters
  • An impedance relay has maximum fault current when fault occurs near the relay
  • A high speed relay has an operation of 1 to 2 cycles
Q2 | Discrimination between main and back up protection is provided by the use ofrelays which are
  • fact
  • sensitive
  • slow
  • none of the above
Q3 | Induction cup relay is operated due to changes in
  • current
  • voltage
  • impedance
  • all of the above
Q4 | A.C. network analyser is used to solve problems of
  • load flow
  • load flow and short-circuit
  • load flow and stability
  • load flow, short-circuit and stability
Q5 | Which of the following statements is incorrect ?
  • Lightning arrestors are used before the switchgear
  • Shunt reactors are used as compensation reactors
  • The peak short current is (1.8 xV2) times the A.C. component
  • The MVA at fault is equal to base MVA divided by per unit equivalent fault
Q6 | To reduce short circuit fault currents are used.
  • reactors
  • resistors
  • capacitors
  • none of the above
Q7 | Bus coupler is very essential in arrangement
  • single bus
  • double bus, double breaker
  • main and transfer bus
  • all of the above
Q8 | For cost and safety, the outdoor substations are installed for voltages above
  • 11 kV
  • 33 kV
  • 60kV
  • 110kV
Q9 | The short circuit in any winding of the transformer is the result of
  • mechanical vibration
  • insulation failure
  • loose connection
  • impulse voltage
Q10 | relays are used for phase faults on long line.
  • Impedance
  • Reactance
  • Either of the above
  • None of the above
Q11 | For which of the following protection from negative sequence currents is provided ?
  • Generators
  • Motors
  • Transmission line
  • Transformers
Q12 | relay is preferred for phase fault on short transmission line.
  • Induction type
  • Reactance
  • Impedance
  • None of the above
Q13 | Distance relays are generally
  • split-phase relays
  • reactance relays
  • impedance relays
  • none of the above
Q14 | For which of the following ratings of the transformer differential protection is recommended ?
  • above 30 kVA.
  • equal to and above 5 MVA
  • equal to and above 25 MVA
  • none of the above
Q15 | A _______ is used to measure the stator % winding temperature of the generator.
  • thermocouple
  • pyrometer
  • resistance thermometer
  • thermometer
Q16 | The relay with inverse time characteristic will operate within
  • 1.5 sec
  • 5 to 10 sec
  • 5 to 20 sec
  • 20 to 30 sec
Q17 | The single phasing relays are used for the protection of
  • single phase motors only
  • two phase motors only
  • two single phase motors running in parallel
  • three phase motors
Q18 | Which of the following devices will receive voltage surge first travelling on thetransmission line ?
  • Lightning arresters
  • Relays
  • Step-down transformer
  • Switchgear
Q19 | Which of the following parameter can be neglected for a short line ?
  • Inductance
  • Capacitance
  • Resistance
  • Reactance
Q20 | Series reactors should have
  • low resistance
  • high resistance
  • low impedance
  • high impedance
Q21 | Which of the following circuit breakers has high reliability and minimummaintenance ?
  • Air blast circuit breakers
  • Circuit breaker with SF6 gas
  • Vacuum circuit breakers
  • Oil circuit breakers
Q22 | Arc in a circuit breaker is interrupted at
  • zero current
  • maximum current
  • minimum voltage
  • maximum voltage
Q23 | transmission line has reflection coefficient as one.
  • Open circuit
  • Short-circuit
  • Long
  • None of the above
Q24 | What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ?
  • Zero
  • Unity
  • Infinity
  • None of the above
Q25 | The inverse definite mean time relays are used for over current and earth fault protection of transformer against
  • heavy loads
  • internal short-circuits
  • external short-circuits
  • all of the above