Restricted Earth fault Relay JRD 013

Additional Details

Principle of Operation:

The Relays JRD 011 & JRD 013 are current operated Microprocessor based, differential relays which work on the high impedance principle. An external series stabilizing 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 used for maximum external fault conditions. JRD 011 is a single pole relay where as JRD 013 is a triple pole relay.

The sensing current is converted to voltage by an internal resistor and this voltage is fed to a harmonic network which is tuned to fundamental frequency. The output of filter is fed to 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. A 'Trip Test' push button is also provided in the relay to enable testing of the trip and alarm circuits. When this push button is pressed, the output element of the relay is energized and its contacts close to energize the trip and alarm circuits.

The relay will not operated at third harmonic currents upto 25 times the setting.

Features:

Software based design

Very sensitive and wide setting range

Insensitive to currents at harmonic frequencies

Trip test facility

Application:

Restricted earth fault protection of transformers, generators and motors differential protection of bus bars, motors and generators.

Burden:

Current input :

Less than 0.2VA at rated 1A

Less than 0.5VA at rated 5A

Auxiliary Supply :

Less than 3W (Non operated)

Less than 6W (Operated)

Aux. Supply :

20 to 60V DC

75 to 150V DC / AC

175 to 300V DC / 185 to 250V AC