• MRK Engineers Private Limited

Electronic Earth Leakage Relay

Earth leakage currents can cause earth fault, sparking, flash over, and deterioration of earthing. These conditions often result in catastrophic fires which destroy life and property. It is therefore, essential to detect leakage currents and isolate the circuit in the event of excessive leakages. Conventional overcurrent and short circuit protection devices like fuses, MCBs, MCCBs, OCBs, etc. are not designed to detect earth leakage currents. The earth leakage relay (ELR) employs a core balance current transformer (CBCT) to sense the leakage currents. In case of leakages either due to insulation failure or direct phase to ground fault, the vector sum of current is not zero and therefore generates resultant flux inducing a voltage in the secondary of CBCT, which is fed to the ELR. This signal is compared with internal references and the instant the pre-set level of current is crossed, the ELR is connected to the shunt trip. No volt coil of the main breaker also opens simultaneously and thus the load circuit is isolated making the installation safe against leakages/earth fault. The ELR is available above 63 amps to 1,200 amps with various CBCT sizes. The leakage current settings are available from 20 mA to 8 amps which will trip the circuit within 30 milliseconds. These conform with various BS/IS/NEC and comply to IE Rule 61-A, 50 and 58.