Principle of operation
This relay operates on the core balance principle wherein the currents in the three phase of the system are summed by a core balance C.T. which for normal conditions equates to zero. In case of a leakage current to earth this balance is disturbed causing the electronic circuit to operate a relay within the unit. In this event the relay that is generally connected to circuit breaker operates thus tripping the main circuit.The electro mechanical relay operates on fault. The Earth Leakage Relay is provided with a TEST push button for checking its operation and a RESET button to reset the relay on operation. This helps in checking the proper functioning of the relay. External (remote) TEST and RESET connections can also be incorporated.
Under healthy conditions OK LED will glow. In case of Fault/Leakage after set time delay the relay will Trip and TRIP LED will glow.