In Power systems there are different types of Protection relays and one of types is Overcurrent relays. Overcurrent relay protection could be designed in an easy and cost-effective way. That is the reason why the Overcurrent relays are mostly used in electrical motors, generators, power transformers, distribution system and transmission line system protections etc. When the fault current occurs in a power system or in an any electrical equipment crosses the predefined or threshold value, it generates a trip signal to the Electrical Circuit Breaker. This paper mainly concentrates on IDMT relay through the software model. In that model single-phase to ground, line to line and three phase faults are taken as the fault for examining the relay subsystem .