Failed Rolec breaker from Artisan Electrics
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- Опубликовано: 25 ноя 2020
- Jordan of Artisan Electrics recently featured this failed circuit breaker from an electric vehicle charger. You can see that video here:-
• Why I Don't Fit Rolec ...
The unit is a combined overcurrent and leakage detection breaker - or RCBO (Residual Current Breaker with Overcurrent protection), which means it provides protection against short circuits and overcurrent as well as detection of AC and pulsing DC leakage. A normal AC leakage unit can't be used for EVs, due to the risk of a faulty charger leaking rectified AC that may not trip an ordinary breaker.
The construction is quite neat, with overcurrent on one side and leakage detection on the other.
The test resistor was hidden down a channel next to a terminal, and is rated 5000 ohms to give a trip test current of a fairly generous 45mA.
The leakage current mechanism is a magnetic latching type that triggers at 15mA by creating an opposing magnetic field to the holding magnetism, that releases the catch and allows it to fly open, striking the trip pin.
The circuitry is effectively a sense coil with diode voltage clamping and the trigger coil tapped across a capacitive divider to allow an element of trip current tuning and probably some filtering too.
The failure looks like typical circuit breaker failure. Very different contact arrangement to the previous one, but still the same failure point as in most standard breakers. Aside from the potential for unusual current waveforms associated with electronic loads, I wonder if atmospheric conditions also play a part due to the higher ambient humidity associated with outdoor equipment.
If you deal with EV (Electric Vehicle) charging pillars and experience breaker failures, let me know in the comments down below what brands are involved. It'll be interesting to see if this is a common issue amongst brands. Let me know if you also think my theory about the power factor correction current pulses being a contributing factor to the failure.
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Thanks Clive! One of your Patreon supporters sent me the link! Great video! Absolutely fascinating.
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"You can always skip ahead..."
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The resistor is right in the corner of the unit in a tiny compartment on its own. Grey in colour, you can just see the end of it.
Rolec breakers are notorious, but it's usually the top-left Neutral that burns - plenty of reports on car forums about this
Thank you Clive, and Jordan.
Never knew about the "magnet thing". Really interesting (as usual), those breakers are pretty packed with components, and "a bit charred inside" may be an understatement!
The main issue with EV charging is it's drawing a heavy load for an extended period of time.
Thank you, Clive! You videos are always both entertaining and educational! Greetings from Sweden!
Thanks Again BigClive. I believe you made this failure mode completely understandable to me. Pretty melty. Maybe not change contact itself but the flipping plastic capturing it. Another great Patron Video for us. Thank you Jordan also.
What I find incredibly interesting here is, all the incredibly thin wires, tiny sensing circuitry, low melting point plastics in the trip mechanism (all of these designed to be the weak point failure points) didn't fail. Nope, it was the beefy bigger current flow contacts that failed (from arc-ing because of uneven contact surfaces) and the heat resistant outer shell plastic that melted, causing more contact failure from plastic residue spitting on to the contacts, and eventually causing enough heat buildup to trip the bimetal strip microswitch. I wonder what would have happened if the melted plastic had glued the main switch contacts together more firmly instead?
Clive, as others have commented I think you have a few things wrong in this video. Power factor corrrection circuits do not draw large current spikes unless they are faulty. Their whole purpose in life is to draw a roughly sinusoidal current in phase with the mains voltage. The do this by using a high frequency switch mode boost converter to supply the main converter with a voltage high than the peak mains voltage and modulating the power they deliver to be proportiional to the mains voltage. The high frequency component of the input current is filtered out leaving a 50Hz sinusoidal current. Also the circuit at
Was waiting patiently for this one after I saw the other video.
Thanks Clive, very interesting video. RUclips is such a great resource, I always learn something from the videos.
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I ALWAYS learn something new with Clive! Thanks for all the cool videos , Clive!! 👍👍😄😄
I did my EV course recently. On it was a bloke who worked for rolec in the past. According to him: 'They buy a container load of the cheapest Chinese breakers/RCDs they can and print a Rolec logo on them."
Excellent forensic work! I believe that many engineers underestimate the effect of the high frequency pulsing current on the contacts.
Great content Clive. Very interesting.