I have a RB16 connected to a U12 with ODC5R relays that I've been using to open and close some Auma electric valve actuators. It has been trouble-free for many years; however, recently, the relays are getting stuck in the closed position when activated. Tapping them will cause them to release.
Nothing has changed in the system so I'm wondering if anyone might know what might cause the sticking.
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Given that you stated that you have had this set up for many years your issue may be as simple as the relays being old. Have you tried replacing any of the relays?
Yes, I tried that.
Have you measured the control signals to the relays? Are the sticking relays receiving an intermediate voltage that would cause them to stick, or are they clearly OFF?
Yes, they are off. If you remove one, and check continuity, they are closed. If you tap them on the table. They open.
I have discovered that some older ones still work but any newer ones I try fail immidiately.
These are closing a 110v circut that draws 30ma when closed.
What I'm probably going to do is just have the ODCR relays control some 24vac mechanical relays to close the circuit. I tried that and that works fine.
Sounds like bad relays If they are sticking when disconnected from your U12. I don't know what would cause them to stay closed based on your description. I recommend verifying the specs to be sure you are not switching too large a load. You might also try exercising them in the event there is some material on the contacts causing them to stick. In any event, it sounds like you have a solution to the problem with the 24VAC relays.
Yes, it's a bit hokey but it works.
-Joe