A detailed look at the trip mechanism in circuit breakers

Given how cheap these are, it's amazing the amount of technology inside them. They have thermal overload sensing for low current faults and they have magnetic short-circuit sensing for high current faults. The trip mechanism is quite complicated due to the need to be able to trip when someone tries jamming the toggle in the on position. It achieves this through a clever double pivot system on the contact assembly. I've taken breakers apart in previous videos, but they always explode into lots of random pieces when the case is separated due to the high number of powerful springs inside. I got some transparent cased breakers from China to explore the mechanism without opening the case. It still took disassembly of one to reveal the clever pivot-point system that lets the contact snap open when the breaker trips. In Europe we have MCBs (Miniature Circuit Breakers) with different trip characteristics for different types of load. Mainly to deal with inrush current. Type B is the most common breaker with a magnetic trip current of up to 5 times the breakers rating. Type C is for high inrush current loads like transformers which could trip the more sensitive type B breakers. A type C breaker has a magnetic trip current of up to 10 times the breaker rating. Type D is for very high inrush industrial loads like welders. A type D breaker has a magnetic trip current of up to 20 times the breaker rating. There are other types, but they are for specialist applications. When choosing a breaker you have to take into account the circuits impedance to determine if enough current will flow to trip the breaker instantly in the event of a live to earth short circuit. That's to avoid the risk of elevated voltage on a grounded case. While making this video I discovered that the contact is at the top of the breaker. I used to think it was at the bottom. That means the arc of an opening contact has to be pulled down into the arc quencher. This video was a bit rambly, as it was tricky working out the best direction to go in when I made the video. After a lot of deliberation I just started recording and let the video take its own path. I managed to do another bench clutter reveal with the current phone's unusually wide zoom range, and also discovered that it makes a bit of focus noise. I've since realised that it was providing haptic feedback for the focus steps. That has now been disabled. I got the transparent circuit breakers from AliExpress (not a sponsor), and they make excellent educational tools. But for actual use in a panel I only recommend buying circuit breakers from local electrical distributors to ensure compliance with local standards. Here's where I got the breakers. You could also search for "transparent circuit breakers". https://vi.aliexpress.com/item/1005008220351614.html If you enjoy my videos, you can help support the channel with a dollar or two for coffee, cookies and gadgets, and keep it independent from the quirks of the YouTube algorithm by supporting me on Patreon. This also lets me link to my content on other platforms if YouTube uses the ban-hammer (again!) I release content for critique and feedback on Patreon as soon as it has been made. https://www.patreon.com/bigclive Alternatively, for a single contribution you can use PayPal:- https://www.paypal.com/paypalme/bigclive #ElectronicsCreators