Theory

It operates when the load current exceeds the preset value. The value of preset current above which the relay operates is known as pick-up current. This scheme is known as over current protection of an element of power system. The induction disc type construction is commonly used. The operation of induction disc relay is based on electromagnetic induction principle. So this can be used only on a.c. circuits and not on d.c. circuits.

Equipments Required

Equipment	Image
Fig.1: Over Current Relay set
Fig.2: Power Chord

Video for experiment: