How a circuit breaker works inside.
Added 2017-11-08 05:18:10 +0000 UTChttps://www.youtube.com/watch?v=JbyTHlx4tQM
I'm going to have to confess that the close-up in this video is not quite as sharply in focus as I'd like it to be, but you can still see the details enough to see how the breaker works.
The majority of breakers like this have two trip mechanisms. A thermal one for low overloads and a magnetic one for high overloads like faults.
You can actually pull a lot more than the rated current from a breaker for short periods of time until the thermal mechanism kicks in, but it's designed to protect the cable from thermal damage by limiting the duration. The magnetic trip characteristic is available in four varieties. Low, medium, high and very high fault current. Those options are to allow for high inrush current loads like motors and transformers. The characteristic is basically a multiplier of the rated current with the type D breaker magnetically tripping at up to 20 times the rated current.
Comments
Another great video Clive. I remember you have done one similar to this about breakers before, I always forget how complicated these 'taken for granted' devices are!
2017-11-10 20:20:26 +0000 UTCI love seeing these taken apart when they haven't burned up or arced over...or become damaged in shipping. That's my lot on a regular basis.
Michael Thompson
2017-11-10 12:10:10 +0000 UTCIf the core was a magnet it would vibrate, but standard solenoids work on both AC and DC.
Big Clive
2017-11-10 01:22:49 +0000 UTCIf I understand the normal current path correctly, it goes through the solenoid coil and moves the plunger to trip the breaker during over current conditions? But as it's AC wouldn't the plunger simply vibrate and not really move that much up or down?
2017-11-09 21:48:59 +0000 UTCDC breakers generally have a much wider contact gap and more serious arc quenching to break the continuous current arc.
Big Clive
2017-11-08 23:52:41 +0000 UTCI have the same problem. I think it depends at which position of the voltage sine wave the power supply is switched on. If the voltage is near to the peak of the waveform it results in a high current into the capacitors and the breaker will trigger? Maybe someone with more knowledge in electronics can confirm...
2017-11-08 23:11:24 +0000 UTCI'd love to see different types of breakers. It seems like low voltage residential breakers in the US are a bit different, though principally the same (thermal/magnetic). Happy to send some
2017-11-08 13:37:54 +0000 UTCI also have disassembled one by myself for curiosity. What a nice considence. π
2017-11-08 12:16:18 +0000 UTCLoved the video. Do DC circuit breakers work in the same way? I know you can't use an AC breaker for DC or vice versa. Would make a great video comparing the two.
2017-11-08 11:02:54 +0000 UTCI learned something from that. Thanks :)
Phil Collins
2017-11-08 09:52:42 +0000 UTCThat makes me wonder tho... I have a 700 Watt power supply in my second (old) Gaming PC, however whenever I turn it off, leave it there so the capacitors will be discharged and then turn it on again the breaker will trip 90% of the time. Sometimes I'm lucky and it won't.
EpicLPer
2017-11-08 08:58:36 +0000 UTCIβd love to see one of these opened and properly tripped on a slow motion camera.
evilution
2017-11-08 06:58:03 +0000 UTC
