Earth continuity relays prefixed gcm.
Earth continuity relay function.
The relay is normally installed in a substation or flameproof enclosure to provide earth continuity protection.
The ecm r earth continuity relay has been designed to monitor the earth continuity of trailing and reeling cables supplying power to mobile machines on an earth fault limited system where there is not a requirement to comply with as2081 2.
This allows non flameproof switches to be used in hazardous areas.
The pilot conductor is connected through an ep041 barrier into the hazardous zone.
The method used is called pilot earth loop or earth continuity.
An earth continuity relay is designed to provide earth continuity protection.
The relay can also as be used as a standard on off control connected to two wires or connected to a pilot and earth of a cable.
The relay monitors the return path resistance between pilot and earth of the cable.
When short circuit between the pilot and earth cores in the trailing cable completes the circuit through the operating relay and if the pilot circuit were not to fail to safety such a fault would cause the motor to start immediately.
The trip level can be set using the rotary switches on the front panel.
This relay is micro processor controlled and can withstand high induced ac voltages and injected dc voltages.
Rather earth continuity protection functions by establishing a loop current through the pilot core returning through the cable earth.
In fact if the motor was running it would become impossible to stop it using the pilot switch.
The loop resistance is constantly indicated on a 7 segment lcd display.
The ecm2 earth continuity relay performs the following functions.
Ensures that there is an earth return path from the machine back to the substation and or distribution box.
A typical example is a pump float switch.
It drives the hmi display interface edm and is also in control of the main circuit breaker.
It has configurable parameters event data logging and selectable start stop functionality.
This is typically achieved using an earth continuity protection relay to apply a low voltage dc signal between the pilot and earth of the cable.
It performs the as nzs 2081 2011 earth continuity protection function on the outlet as well as receive and process the signals from the power interface.
