Cor van de Water via EV wrote:
I am sure that this test is done in software just to verify that everything works, just like there is a special relay that will *create* a GFCI event just to test the detection of GFCI before relying on it. Most standards actually do not specify what happens in transition (such as power up)
I agree. It is common practice for a product to test its own safety circuits automatically, one way or another. The standards were written to allow and even encourage this.
Relay contacts can stick closed. If you want to be sure a relay opens, then monitor its contacts and operate it.
I recall one product where it was vital that its AC output could be turned off in an emergency. So we had *two* relays, with their contacts in series (one switching one hot lead, the other switching the other). The safety test circuit closed and opened one relay while measuring its output to be sure it worked. Then it repeated this test with the other relay. Only if both passed did it turn on BOTH relays to power the load.
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