IDMT (Inverse Definite Minimum Time) Relay Calculation
IDMT (Inverse Definite Minimum Time) Relay Calculation

Overcurrent and Earth Fault Relay Setting

Setting calculation is separated for overcurrent and eart fault relay. For both settings, there are few following input parameters:

  1. Name of Feeder
  2. Load Current: (IL) in Amps
  3. Min Fault Current (Line-Line) in Amps
  4. Max Fault Current (Line-Line) in Amps
  5. Relay Type
  6. Relay Code
  7. Relay No
  8. CT Primary Current (in Amps)
  9. CT Secondary Current (in Amps)
  10. Relay Error (%)
  11. CT Error (%)
  12. Over shoot (in seconds)
  13. C.B Interrupting Time (in seconds)
  14. Safety (in seconds)

Summary of overcurrent and earth fault relay settings:

  1. Actual Plug (Relay Pick up) setting
  2. Plug Setting Multiplier (PSM)
  3. Time setting
  4. Total Grading Time
  5. Low Over Current Setting: (I>)
  6. Actual Operating Time of Relay (tI>)
  7. High Over Current Setting: (I>>)
  8. Actual Operating Time of Relay (tI>>)
Software:IDMT (Inverse Definite Minimum Time) Relay Calculation
Developer:Jignesh Parmar
Size:39.1 Kb
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IDMT (Inverse Definite Minimum Time) Relay Calculation

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Page edited by E.C. (Google).


  1. praveen
    Feb 15, 2017

    Sir I want complete report about IDMT relay over current

  2. sundar
    Aug 15, 2016

    i need password of relay idmt calculation sheet.can you please tell me how to unprotect that excel sheet

  3. swap
    Feb 17, 2016

    can we use ODMT oc relay in for short circuit protection?

  4. chandresh
    May 02, 2015

    what is the meaning of overshoot in relay… please describe

  5. mne amin
    Apr 15, 2015

    hm waiting to your reply


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