Inside a very old RCD/GFCI (no electronics)
Added 2021-05-13 04:01:36 +0000 UTCThis is a teardown of a very simple early RCD/GFCI. So early that it was still called a current operated ELCB (Earth Leakage Circuit Breaker).
There's also a story of why it had to be replaced.
Comments
Just mentioned this to a colleague and it reminded me that an unseen fault is an unfixed fault. I try to factor that in when I do a product safety analysis. At the end of the day - like it or not - handbook warnings aren't there for fun. They're to cover the manufacturer's arse and shift responsibility to the user. Fortunately none of my products have ever been to court.
Mike Page
2021-05-26 15:43:38 +0000 UTCThat sounds like an early Voltage Operated ELCB. Less versatile design phased out with the newer current differential type.
Big Clive
2021-05-18 01:49:26 +0000 UTCI once found an even older protection device, that relied on a different principle. It had a solenoid connected between earth (TT system) and neutral that triggered if the voltage exceeded a certain value, like 50V or so. Not very accurate, but the principle is valid.
Karl Langeveld
2021-05-17 19:18:18 +0000 UTCYes, I'd certainly think so! Having said that, the current at 11kv would be approx 44 times less, so a 30OHM earth like yours, would loose about 75v on the street side, would translate to less than 2v on the 240v side. That would be if the load on the 240v side was running at about 100a, probably way more than most people ever would! I'd say, though, it is certainly a case for having separate earths for the swer, and the house earth, presumably a *long* way apart!!!
William Taylor
2021-05-15 03:31:14 +0000 UTCI've seen the single wire system in use and amen't convinced it's a good idea in areas prone to drought. Ground borne voltage gradient must be an issue at times.
Big Clive
2021-05-14 17:04:59 +0000 UTCYes I did. I'm an electrician to trade (traditional four year apprenticeship with an electrical engineering company) and wanted to do a thorough test of the wiring anyway. It passed all the tests and only required some additional bonding to bring it up to date.
Big Clive
2021-05-14 16:52:57 +0000 UTCSooooo, did you replace your entire consumer unit? When was the last time you had a COMPETENT spark perform an EICR? I'm guessing with a rewireable fuse board, you have not had an EICR in a Looong time. Also, please do not mistake my questions as criticism. It is merely concern for your safety.
Chuck Kirchner
2021-05-14 03:00:45 +0000 UTCStuxnet? It was a virus that purportedly targeted Siemens PLC programming software. I'm not sure how much of the information is folklore regarding specific targeting of centrifuges. You'd really need the wiring diagram of a piece of specific equipment like that to know which aspects to interfere with.
Big Clive
2021-05-13 19:04:36 +0000 UTCThey were Siemens PLC systems
Jonas Otter
2021-05-13 16:41:53 +0000 UTCA wonderful exploration and this was from your house as well, in operation through the years. So cool!
Michael Thompson
2021-05-13 10:00:10 +0000 UTCThe Iranian reactor damage was reported to have been caused by the worm Stuxnet. Allegedly a joint project between US and Israel. It was delivered via USB stick and destroyed high speed centrifuge motors causing them to run unbalanced. The recent US problem was reported as a typical internet driven ransomware attack. I haven't heard how they did it here physically. I did hear rumors that the Stuxnet worm may have played a part in unprotected Fukushima backup systems failing but that was more speculation from people. There is a good documentary out there on the Stuxnet worm.
Jim
2021-05-13 08:47:03 +0000 UTCDo you know anything about the switch gear that gets hacked ? I keep hearing about old Siemens switch gear that got hacked causing problems. US oil lines, Iranian Centrifuges ? And what Siemens have done to change them.
Jeremy Travis
2021-05-13 07:55:46 +0000 UTCYes, actually, in rural areas here, they run a swer system (single wire Earth return) at 11kv. Each property has a transformer with 11kv in and back to earth. The secondary has a center tapped 480v winding and the CT is earthed too, so you get a 180degree 2 phase supply. at least at 11kv the resistance doesn't matter so much, but I'm not sure if they use the same steak for both, I'd suggest not!!!
William Taylor
2021-05-13 06:31:21 +0000 UTCToo right !!! I remember the advice / quote for work my mum had from an “expert” …….. seen too many examples, some good ones out there but some with very little training and really don’t understand.
RDM
2021-05-13 06:06:13 +0000 UTCSimilar in UK on most properties (typ TNC-S / PME now, with some TNS) TT supplies usually old properties and rural locations but should have working RCD so a fault will be detected. Older systems as well had much more Earth bonding do surfaces would be equipotential
RDM
2021-05-13 06:02:24 +0000 UTCStrangely enough I wouldn't trust anyone presenting themselves as Part P. It's symbolic of the deskilling of the industry brought on by "that" company that pretends it's an official body.
Big Clive
2021-05-13 06:00:43 +0000 UTCReally enjoyed that Clive - years since I’ve seen one of those, VOELCBs still found around here (it’s rural so lots of old TT) and still amazes me how well the old gear lasts - I do hope you had a fully part P compliment ‘expert engineer’ change that 🤣
RDM
2021-05-13 05:56:07 +0000 UTCInteresting device! I do have to say, though, that your 8A fault makes me greatful for the MEN system here in Aus, as this would have not made my fridge or whatever live against, say the kitchen sink and killed me!!! So, it could have gone on causing you some very heavy power bills that way, I wonder how many people there have a live earth and have no idea it's there. At least here, the fault would have banged very nicely, and made it's self rather obvious in very (short) order!!! For those who don't know what the Australian MEN system is, the grid Neutral/earth is connected directly to every steak at the hous at every meter box.
William Taylor
2021-05-13 04:42:03 +0000 UTC
