Control Relay

[burntcoil]

Good Day,

I am considering to use IDEC control relays in the trip and close circuit of Low and Medium voltage Switchgear. Can any suggest me the model from IDEC whose contact rating will be good enough to be used in breaker trip/close circuit.

Thanks

 

[davidbeach]

The breaker aux contacts clear both the trip and close circuits once the breaker operates. All your control relay has to do is make and carry the trip or close current, but not interrupt it. Look at the contact ratings of typical protective relays.

 

[oldfieldguy]

Dsvid makes a good point. On your application, you need a feedback loop to make sure that the control relay contacts do not open while the relay is passing the trip or close current. Some users just make that contact closure and one or two-second one-shot, thinking that this is more than enough time for the breaker to receive the signal and react appropriately, letting its internal contacts open to interrupt the current.

Others use a breaker open-close status to drop out the control relay, in other words, when a close signal is sent to the control relay, the relay remains energized until the system sees a 'breaker closed' indication, then it drops out.

This functionality is built into some modern protective devices. IN interfacing with PLCs, we need to provide for it ourselves.

old field guy