How do these 2 wire, 32VDC, 125VAC, 15A push button reset breakers work ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: March 15, 2022, 06:01:30 pm
content: I'm fixing a stove, and I found a push button reset break, in series w/ the 125V outlet of the stove-top. And it's open, and doesn't seem to work. And it says it's 32VDC, 125/250VAC, 15A, so I'm just wondering how they work, especially being 2 wires, and maybe it's not broken, maybe it's not getting 32V anymore. The outlet doesn't work, but neutral is there, and 1 hot wire goes to that breaker. There's a heat-shrinked fuse on the outlet, it's fine.I'll check the model number, but it's basically like these I thinkhttps://www.monsterscooterparts.com/catalog/product/view/id/23646/s/15ampcibr/

author: SeanB
author_rank: Super Contributor
timestamp: March 15, 2022, 06:39:34 pm
content: Thermal circuit breaker, inside there is a bimetal actuator, either a click type disk, or a simple length of the bimetal, that has the current flowing through it. At some current it will heat up enough to either release a plastic latch, or pop the disk to the other state. Either one will break a set of contacts that allow power to flow through, breaking the circuit. Very common for these to fail, and need replacing, you buy a new one with the right terminals and mounting, and put it in place of the failed one. Good thing for there is that the failure mode is almost invariably to fail open, though the contacts are well known to weld themselves together, so the unit will overheat till it melts the contacts open again, normally fatal for the unit. Fuse is there because they do not respond well to short circuits, so need a back up fuse for handling short cicuits, though they work well for just overloading.Rating is 32VDC if you are using with a battery, no more than 32V, so basically a 24V car or truck system, and the 125VAC rating is for AC use, where the slow opening of the contacxts will not cause an arc, as the mains voltage falling to zero 120 times a second helps extinguish the arc and allows it to go out. 32V there is not enough voltage to sustain the arc when it opens, but above that the arc can carry on till something else fails.

author: floobydust
author_rank: Super Contributor
timestamp: March 15, 2022, 06:42:00 pm
content: These are jelly bean thermal circuit breakers, found in power bars as well.If the reset button doesn't work or stays sticking out, then I would say it's failed. I use them in hobby projects as well asTyco W58series."32VDC 125/250VAC" is the interrupt (contact) rating, they don't actually require any power to work. They are like a switch that gets hot enough past ~145% of their rated current and trips.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 15, 2022, 07:56:10 pm
content: Yup, most likely just thermal.If you're curious, the other kind of breaker is thermal-magnetic: it's the same thing, but also with a solenoid that pulls the mechanism off at very high currents (1000A+). This is how panel breakers can open quickly (10s of ms) under fault currents.Or the RCD / GFCI type, which have a current imbalance detector driving a trip solenoid; this solenoid has many more turns on it, and is momentarily connected across the load, greatly amplifying the signal and tripping it quickly enough to prevent/reduce ground-fault electrocution incidents. Which is also why they have a TEST button: if that solenoid gets stuck on, it'll auto-pop itself; if it goes open, TEST won't work anymore and you'd better replace it.Tim

author: MathWizard
author_rank: Super Contributor
timestamp: March 15, 2022, 09:14:40 pm
content: Ok thanks, I never considered it's just a DC rating, I figured it was something new, but seeing as how it seemed wired in series w/ AC mains, I can't imagine what it would be