QUIZ - Differntial Protection of Transformer



  1. Differential protection should be provided in the transformers whose rating:
      2. Above 5 MVA
      Below 5MVA
      Above 50 MVA
      Below 50 MVA

  2. The differential protection of transformer does not cover the following fault:
      3. Winding to ground fault
      Winding to winding faults
      Inter turn fault in any winding
      short circuit faults at transformer bushing

  3. Which type of connection is employed for current transformers for the protection of Delta- Star connected 3-phase transformer:

      4. Detla-Star
      Star-Delta
      Delta-Delta
      Star-Star

  4. Which Differential protection principle is used in the protection of transformer:
      5. Current difference
      Voltage difference
      Power difference
      power factor difference

  5. In differntial protection of transformer the CTs on both side of transformer are:
      6. Identically same
      Their turns ratio has inverse relation
      Their turns ratio has no relationship
      None of the above

  6. A differntial protection protect transformer from the following fault-

      7. Over current due to overloads and external short circuits,
      Interturn faults
      Oil leakage faults
      Incipient internal faults.

  7. How does the tap changing effect of transformer can be nullify in differential protection of transformer:
      8. By changing CT ratios;
      Using restraining coil
      Providing tappings in relay coil
      none of the above

  8. In pole mounted substation, which protection is used:
      9. differential protection
      Earth fault protection
      DO Fuses
      Buchholz relay

  9. The differential protection is used for which type of transformer:

      10. Oil cooled Transformer
      Air cooled Transformer
      SF6 gas cooled Transformer
      All of the above


  10. In differential protection the relay is connected:
      11. Near Current Transformer
      Near Transformer bushings
      At equipotential point of pilot wire
      Near transformer tank