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. It also has an inbuilt CBCT open/breakage protection wherein the relay will trip on CBCT connection being open.
Under healthy conditions OK LED will glow. In case of CBCT secondary is open CBCT OPEN LED will glow and after set time delay the relay will trip and CBCT OPEN FAULT TRIP LED will glow. In case of Fault/Leakage the FAULT LED will glow and after set time delay the relay will Trip and FAULT TRIP LED will glow.