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Same relay contact wiring to PLC in parallel to solenoid

Same relay contact wiring to PLC in parallel to solenoid

Same relay contact wiring to PLC in parallel to solenoid

(OP)
Hi
I have a solenoid wired to a trip relay contact which is programmed to trip on high temperature. The trip relay is having only single contact. Now I would like to wire this trip relay contact to a Allen Bradley MicroLogix PLC so that I know when the solenoid is tripped via the relay contact. I am planning to connect the contact to PLC's digital input as per the attachement. I think it should work. Your comments please.

RE: Same relay contact wiring to PLC in parallel to solenoid

No attachment..

Probably NOT a good idea because the solenoid will be generating occasional LARGE spikes when de-energized. The PLC will have built-in snubbers to accommodate that but they're typically not designed to handle solenoids only smaller relay coils. You should consider using a second relay or much much better a two pole relay and just use one set of contacts for the PLC.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Same relay contact wiring to PLC in parallel to solenoid



Hi Novice.

That will work just fine. For some reason I thought you where talking 120/240VAC not DC where a freewheeling diode directly across the coil does a great job of dumping off the spike.

Is that really -24V??? or 0V?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Same relay contact wiring to PLC in parallel to solenoid

Was wondering the same. I bet a nickel on 0 V. Maybe even a grand.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Same relay contact wiring to PLC in parallel to solenoid

Gunnar you're turning into a chronic gambler!

You need more shocking-shrimp jobs.spin2

Keith Cress
kcress - http://www.flaminsystems.com

RE: Same relay contact wiring to PLC in parallel to solenoid

With a boring life like mine - I can't help seeking excitement whenever possible.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Same relay contact wiring to PLC in parallel to solenoid

(OP)
Thanks Guys
It is 0V bigsmile

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