QUIZ - 11



  1. What is the purpose of back up protection?
      2. To increase the speed
      To increase the reach
      To leave no blind spot
      To guard against failure of primary

  2. What is the actuating quantity for the relays?
      3. Magnitude
      Frequency
      Phase angle
      All of these

  3. The Induction Motor failures are mainly due to:

      4. Electrical faults
      Mechanical stresses
      Environmental conditions
      All of these

  4. What are the protections in starter of 3-phase induction motor:
      5. Limiting starting current
      Overload protection
      No-voltage protection
      All above

  5. Name the protection used for induction motor from overload, single phasing, locked rotor and earth fault:
      6. fuses
      numerical protection
      Protection in starter
      None of these

  6. In textile machines, to avoid breaking of threads, soft starters are used. The commonly used method in soft starter is :

      7. Direct online method
      Star-delta method
      Thyristor voltage controller method
      Thyristor current controller method

  7. Torque of an induction motor can sometimes be given in synchronous-watt. One synchronous-watt is equal to:
      8. 60 / (2 *pi* Ns) N-m
      (2 *pi* Ns) / 60 N-m
      120 / (2 *pi* Ns) N-m
      (2 *pi* Ns) / 120 N-m

  8. The air gap flux of induction motor does not contain:
      2nd harmonics
      3rd harmonics
      5th harmonics
      7th harmonics

  9. L&T MPR 300 protection relay used for induction motor protection is an :

      10. Analog electronic relay
      Digital relay
      Both (a) and (b)
      none of the above


  10. MPR300 protection relay is used for :
      11. Single phase induction motors
      Fractional hp induction motors
      3-phase indution motors upto 85 hp rating
      3-phase induction motors above 85 hp rating