I've been given a collection of residential service panel breakers and would like to check them to see if they trip correctly. They were in use before I got them, so they certainly close correctly, but it's unknown if they trip correctly.
As it happens, I have an AC arc welder which can be set between about 20 and 200 amps, with an open circuit voltage of about 80 V.
Anybody ever tried this? Does it seem an unrealistically harsh test?
Thanks for reading,
bob prohaska
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** Nope - such breakers are rated to open instantly with fault currents in the thousands of amps. At rated current they will take a while, maybe 20 minutes, since the trip mechanism is thermal rather than magnetic. FYI: A neat, low cost test is to connect an electro cap of about 100uF / 400V with a 6 amp series diode across the output. The peak surge should trip the breaker pronto....... Phil
At least traditional welders (line frequency not switched mode) look very inductive, and are designed to sustain an arc. Whilst I would hope that the circuit breakers are able to break the arc, it is a much harsher test than with a resistive load. If the welder is able to sustain an arc after the circuit breaker opens, then this will destroy the breaker.
I agree it's a harsh test, but the breakers were free. I'd rather not use them without some evidence they work.
After posting my question I again searched the web and found one set of YouTube videos demonstrating overcurrent testing of breakers and connectors. One suggests that at least some circuit breakers can stop an arc welder without self-destruction. It's at
bob prohaska
DC ratings of standard breakers seldom exceed 40V, due to arcing. AC arcs are interrupted by line voltage reversal, preventing damage. But even these have a limited guaranteed operation count.
RL
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** However most *mains rated* breakers employ magnetic or physical barrier arc quenching whenever contacts open. ** Strange how AC arc welders work so well then. FYI:Relays and most switches suffer from limited DC switching capacity, usually limited to 24 or 30 volts at rated currents. Any more results in a permanent arc bridging the contacts, followed by complete self destruction. Relays used as "speaker protection" generally do not.
...... Phil
Not so much quenching, as sacrificial absorption, in locations that are not relied on for physical working contact area. Life-limited, bulky and $$$.
Wadabaudit? Nobody's saying that AC won't arc.
They don't work so well, because an arc has to be re-established on every cyclic reversal. Breaking the AC arc is 'easy'. Maintaining one is hard. AC arc welding produces spatter. Industry preference is for smooth.
What AC welding is, is cheap.
Sometimes, for some types of metal, or for delicate work, having an easily broken arc, or repeatedly forcing a restart has an advantage. For highly magnetic material, it avoids 'wandering'.
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** Hello to the smug troll calling itself " legg" .The term "quenching" here clearly refers to physically breaking an arc by extending it. Rest of your pedantic, tedious, self aggrandizing, spew inducing BULLSHIT snipped. Have a really rotten day.
.... Phil
Welcome back Phil!!!
John
G'daye.
RL
If they're thermal breakers, the only part that can fail while retaining the on/off function is a heater. A welder intended to melt metal applied to a heater is... maybe not a test that should be applied.
The heater, if it fails open, won't let the breaker pass current. If it fails closed circuit... there's extra metal inside the breaker?
Circuit breakers should, and generally do, fail in safe ways. Go ahead and use them without applying a stress test beyond normal currents and voltages.
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