An analysis of time current characteristics of adaptive inverse definite minimum time (IDMT) overcurrent relay for symmetrical and un-symmetrical faults

The paper presents the analysis of the time current characteristics (TCC) of the IDMT overcurrent relays. Overcurrent relays are subjected to the change in conditions of time delay (TD), Pickup settings and PSM (Plug Setting Multiplier) which are an essential substance for adaptive relaying. Overcurrent relays should operate reliably during the normal operations and enhanced fault conditions. Alteration in different parameters results in adaptive setting of overcurrent relays, according to the fault conditions and its values. During analysis, the IDMT overcurrent relay settings which are TD and PSM is infused according the protection level required for the different level of faults and load current. Variation of fault is perceived and TCC curve is analysed, which is then altered to acquire the optimum level of protection. The research is primarily focused on the behaviour of overcurrent relay parameters by changing the assessment effectively through analysis of the TCC curve by analysing the fault current in power system. Substantial flexibility aids in superior adjustment of overcurrent relay to ensure adequate device coordination. Effective and reliable analysis of the curve helps in the compelling reassurance of the power system protection.