Neutral Earthing Resistor Monitoring Relay JRV 402

Additional Details

Very low DC current flows through the NER and is monitored in the relay. If there is an open circuit in the resistor or a considerable change in the value of the resistor, this is detected in the monitoring circuit. After detecting the change, the timer is short-circuited and the output relay is de-energized at the end of the internal delay (5 sec.). The relay contact can be externally connected to the alarm/trip circuit as required. Normally, the output relay is energized. If there is a fault in Aux. Provide the output relays and extend the alarm/trip signal.

Features:

Solid state reliability

Integrated test facility

High sensitivity

Low charge

Insulation:

2KV RMS, 50 Hz for 1 minute / 2.5 KV for 1 sec Between all terminals and cases.

1KV RMS, 50 Hz for 1 minute across open contacts

Application:

The relay is used to monitor the neutral grounding resistance. The neutral of the transformer is grounded through a resistor. This resistor is called the neutral grounding resistor (NER). Neutral grounding resistors are used to limit the fault current across the transformer during ground fault conditions. The health of TNS is important because open resistance would make ground leakage protection operational and dangerous.