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ripnc avatar image
ripnc asked

Relay 2 will not turn off by temp or manually.

Cerbo-S GX ver 3.31 (down from GUI2 ver 3.40) had a 3A fan operating on temp and relay seems to have stuck in On when on GUI2. Went back to 3.31 and no joy. Have rebooted several times and also tried removing power to Cerbo itself. Also, tried manual Slide switch. I've done this w/o the load (fuse pulled) and still have continuity between NO and COM (I tested the plug when pulled and it was open as expected). Any ideas?

cerbo gx
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3 Answers
ray42 avatar image
ray42 answered ·

Hi there,

I experienced the same issue today on my relay 1 port. Attached a 48v->12v 1A converter to run 4x 60mm fans on it. Made a temperature rule for that and everything worked fine for a few hours. The rule trigged 3-4 times on and off.

In the evening I checked on it and the fans were still on, although the relay showed „inactive“.

I checked every possibility and I hear a click when the relay should switch, but it doesn’t cut the power.

In the end I flicked with my index finger on the cerbo GX case near the relay and the relay cut off. It seamed to be stuck somehow. After that it worked again and switched accordingly. Will monitor it and report back.

Maybe this helps you, although I think it can be dangerous for everyone if the relays do not switch as intended.

Regards

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ripnc avatar image ripnc commented ·
Thanks! I knew I should have tried the bigger hammer approach ;-) I'm going to give it a shot tomorrow (pun intended).
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pwfarnell avatar image
pwfarnell answered ·

Have the contacts welded closed in both your cases. We recently had an example of this on here. Have you checked the current draw against the specs for the relays. I know that the manual states DC up to 30VDC: 6A, DC up to 70VDC: 1A which may cover steady loads, but in both your cases you appear to be running loads that could pull much higher current for a short duration, a 3A motor could pull well over 10A at start up, a 48-12V converter likely has capacitors on the input side that would need precharge. I would use the Cerbo relay to drive a more powerful relay with appropriate flyback diodes.

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ripnc avatar image ripnc commented ·
Thanks. Will check the draw, but I do have a 5A (12v) fuse inline on the COM wire, fan calls for the 5A fuse. Is there a way to tell if they somehow welded? I gues not a repairable issue, correct?

Thank you.

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ray42 avatar image
ray42 answered ·

Makes sense what you say. Will check on how to measure the startup surge of this miniconverter.

I have a 3A fuse inbetween the 48v busbar and the com port of the relay. Didn’t had a 1A on hand otherwise I would have added this.

The fans are 4x 12v 0.18A.

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