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MRIK3 – Time overcurrent relay with auto reclosing relay

What is the formula for overcurrent relay?
Calculation of Over Current Relay Setting:
 Operating Time of Relay for Normal Inverse Curve (t) =0.14 / ((PSM) 0.02 -1).  Operating Time of Relay for Very Inverse Curve (t) =13.5 / ((PSM)-1).  Operating Time of Relay for Extreme Inverse Curve (t) =80/ ((PSM)2 -1).
What is AC time overcurrent relay?
AC Time Overcurrent Relay (ANSI/IEEE C37. 2 device number 51) that operates when the current exceeds a predetermined value.
What is overcurrent relay and earth fault relay?
The main functions of the Overcurrent and Earth Fault Relay include: Three-phase earth and overcurrent: three independent stages.
The first stage selectable from any of 12 IDMT curves; the remaining stages having a direct time characteristic (ANSI 50/51 and ANSI 50N/51N).
IDMT over the current relay protects the transformer from external faults.
It is one in which the time of operation is inversely proportional to the magnitude of fault current near pickup value and becomes substantially constant slightly above the pickup value of the relay.

What is the formula for overcurrent relay?