• JVS Electronics Private Limited

Restricted Earth Fault Relays

JVS Electronics offers a Restricted Earth Fault Relay, Type JRD 011/013. These relays are basically current operated; software based, differential relays, which works on the high impedance principle. Features: software based design; very sensitive and wide setting range; insensitive to currents at harmonic frequencies; negligible burden; trip indication with LED; trip test facility; dust proof enclosure; and compact size. Application: restricted earth fault protection of transformers, generators and motors; and differential protection of bus bars, motors and generators. An external series stabilising resistor is used with this relay to make it a voltage-operated relay. The voltage setting of the relay is adjusted to be higher than that developed by the current transformers under maximum external fault conditions. JRD 011 is a single pole relay where as JRD 013 is a triple pole relay. The power required by the electronic circuitry is drawn from the auxiliary DC supply. The sensing current is converted to voltage by an internal resistor and this voltage is amplified and fed to a harmonic filtering network, which is tuned to the fundamental frequency. The output of the filter is fed to a voltage comparator. When the sensing current signal at the fundamental frequency exceeds the set value, the comparator gates a train of pulses to the processor. The program residing in the CPU performs the function of control and also gives output signals for relay and LED driver circuits. The operation of the relay is indicated by the glowing of a "Red" LED, which has to be reset manually by means of a " Reset" push button provided on the front of the relay.