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.

Principle of Operation:

Type JRD 011 & JRD 013 are basically a current operated, software based, differential relays which works 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 maximum external fault conditions.JRD 011 is a single pole relay where as JRD 013 is a triple pole relay.

The fundmental 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 (central processing unit) performs the function of control and also gives output signals for relay and LED ( Light Emitting Diode) driver circuits. The operation of the relay is indicated by the glowing of a 'Red' LED , which has to be reser 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.

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