• Software based design
• Very sensiytive and wide setting range
• Insensitive to currents at harmonic frequencies
• Trip test facility

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

The Relay JRD 013 are current operated Microprocessor based, Three pole, Differential Protection Relay 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 condiytions.

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 funcytion of control and also gives output signals for relay and LED driver circuits. The operaytion 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 tesyting 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 oper ated at third harmonic currents upto 25 times the setting.