Failed elevator switch fuse / fusible disconnect
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- Опубликовано: 2 окт 2024
- This is a common industrial grade switch-fuse unit used for isolation and protection. The unit in this video had failed, so I thought it would be interesting to see what had gone wrong.
Note that the failed module also had a loose bit of plastic in it, and that may have contributed to the unusual failure.
The contacts are notable for having a ball joint effect at one end, which ensures they always sit flat on the other contact. The spring loaded mechanism is basically two very powerful springs acting as an over centre toggle which will snap open and closed with force, rotating the common switch operation bar.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.co...
This also keeps the channel independent of RUclips's advertising algorithms allowing it to be a bit more dangerous and naughty.
The fuse may have failed but that means the elevator won’t let you down!
Let's go crazy
Let's get nuts
Look for the purple banana
'Til they put us in the truck, let's go!
I endorse this message! Haha
Yeah but you can't get it up either
Mind of a Evil Genious😂 Ha ha ha haaaaarh, First I shall take over my Town....Then the World......Har har harrrrr harrrrrrrrh
@@daviddavidson2357 who told you ffs?🤔😳🤪🤪
Regarding skipping or speeding up the video, I personally like to see the whole messy gutting process in detail from beginning to end, including what mistakes not to make and learning old and new methods of how things are put together (helps spot potential embarrassment when taking other things to bits). Your videos are always informative or fun or both.
Yes! This is an essential part of Clive videos for me!
The main reason I watch these videos is to watch a Scotsman slowly and methodically break things in new and unique ways
Yeah for sure one of the reasons I enjoy this channel so much is the satisfying destruction in between learning things about electronics engineering.
"This spring was made for pingin, and that's just what it'll do... This spring is gonna ping all over you"
No friend, you forgot _One of these days._ But don't edit your comment or you lose the heart.
One thing I've learned, through the unauthorized puncture of my skin from spring loaded bits, is that if you are worried about a spring, first loosen all the screws, and if it's pushing back, stop right there and reassess
Usual trick. Then take one screw out, see how long it is before it's out of the thread so you know how long the rest can come out before they let go. One of the problems can be that the nasty spring is in a loose component - so you don't find it pushing outwards - but then a loose bit inside explodes when you least expect it.
No! Best way is, have someone else do it... :)
Spoken like a garage door replacement person? Those counter-balance torsion springs will happily remove limbs.
@@R.Daneel I just turned 16 on the 12th of april, living in the US I can only legally hold a permanent job now that I'm 16. But I have worked with those springs before and they're scary. I used a magnetic decelerator my uncle gave me (he used to be a roofer and to be osha compliant, you need one) and essentially crossed my fingers and let the spring go attached to that thing. There shouldn't have be much tension on it but the guy that installed was apparently a moron, because when the door was open it'd be under tension and without the garage door opener it'd pull the door about two inches (about 5cm) off the ground
@@R.Daneel I have seriously thought about those as an energy source for starting car engines without electricity. Any multi-wind springs - like on recoil engine starters and tape measures have amazing abilities to spring totally uncontrollably if not securely controlled !
Many years ago I enjoyed the first Jerasic Park movie. Some years later I went to work at my first maintenance job. I never knew the most realistic thing about that movie was the breakers (disconnects/fuse switch) that you have to pump to restart.
Ha ha ha, great observation. Only a Techie could notice summit like that?😂
Really true! It's common to see spring loaded breakers where you do need to manually load up the spring or the brake has a solenoid/motor to do it.
The most surprising thing for me is that one they used in the movie (Westinghouse SPB-100) was truly expensive (tens of thousands of dollars) yet they still somehow managed to get it into the film, rather than opting for something cheaper mocked up to look fancy - no expense spared I guess. Given my love of electronics and electrics it's one of my favourite parts of the movie.
@@Berkeloid0 Very likely they just borrowed it from the studio maintenance department, as the power demand for a film set is big enough to have power systems more in size for a large industrial area, in an otherwise small space. Easy to pull an entire cabinet from an unused set for this, or even film in situ and cut in the scene later as well, and use a spare in the set for scenes where it is only there for view.
I haven't heard of a "Jerasic Park" movie. Is it anything like Jurassic Park?
"Bear with me" No, Clive. The bear is with us. 😂
😂
Or beer?
Fur-rocious.
12:20 when he takes off his gloves to work with his bear hands. (These jokes write themselves.)
@@Gameboygenius Yes, they do!
I'm very thankful that Clive makes these videos covering the more industrial side of things. I didn't realise how much it would help me with my current job back when I was watching when I was 16. As someone who writes operating and maintenance manuals its nice to understand things on a component level :)
They don’t explode when being taken apart. They can however undergo ‘uncontrolled rapid disassembly”
Or like SpaceEx, unscheduled, non-commanded self disassembly?!
I love that term. I'm stealing it.
@@whitesapphire5865 - Maybe it blew the lithium battery pack :-)
I’ve had my share of those lol
_"Mofo spring"_
Ahh the technical term! XD
Nice to end the day with the soothing sounds of Big Clive's voice
or someone felt sorry for the poor thing knowing it was going to spend it's days locked in an enclosure far from light and air . . . so they took it for a day at the beach.
That's like sand in your shorts at the beach. 🤣
Chaffage.
Natural exfoliation, nowt bad about that shizzle. Part of the The lazy man's grooming routine...my type of easy lifestyle choice....
@@bigclivedotcom Good Chaffage...There's cream for it anyway, so no issues there.🤔😁
Impressive detective work!
Also I felt so proud when I figured out the arc quenching before he said it aloud.
I supose one option for those that prefer the pauses is to include time codes in the video description (and if you put a time code for each part of the video, including one for 0:00, then the time codes will turn into video chapters, assuming the feature works as it is supposed to)
Well I was going to say I had a brief opportunity to try this, and i get to the end of what you were saying and I was like it actually works amazingly well.
Literally all you have to do is put text with a number and it creates a chapter as in : "0:00 the beginning of life the universe....." Just recently did a video and I was so expecting to have to look it up, I edited the description and boom.
I helped build a power distribution cabinet for the Albert Hall. Huge thing that needed to be curved and modular to fit it into the switch room. Had many units like that. 2x👍
As for the sand, a very common cause for failure is people drilling in walls over electrical cabinets that dont have good ingress protection. Cable ducts/conduits also can blow dust into cabinets due to pressure difference between rooms, which is why it is prefered to have the conduit end before the cabinet and use a cable gland on the individual cables.
Fucking people drilling the entire walls in the house
@@SpeedsGamer Isn't that more like 'demolition' than 'drilling'?
Yeah, and less skilled electricians drilling holes in cabinets with nothing to protect against swarf going into terminals and switch mode power supplies.
@@westinthewest sometimes it sounds like it!
@@bigclivedotcom I have had a few contactors that mysteriously had one pole not make contact anymore, even though they looked fine, just a tad dusty. Under the microscope, there were hard (probably quartz) particles pressed into the soft contact material, keeping the contacts apart far enough not to touch anymore. With 400V and large rounded contacts, it takes surprisingly little not to arc over. Root cause was quite evident, last time some contractors ran pipes above the control cabinets, and didnt bother with a vacuum cleaner or anything while drilling holes to anchor the pipes, and the cabinet had missing and ill-fitting cable glands on the top.
Clive, you say on your first day in the steel works you were installing slate switch gear, you started work in the "Stone Age"!
That would be large slate slabs used as and insulated panel to mount live contacts and conductors... fully exposed contacts and stuff like knife isolation switches. This was used before plastic and composite panes [stuff contains a asbestos and mineral dust bonded with stinky tar like compound] were developed.
The marble panes I've encountered must have been an 'up market' version of the open stone faced boards - Zero IP rating - NO isolation factor! High danger factor!
At least the marble was a pretty white colour and not a nasty grey.
Bit of a bugga to have to install a new switch or cutout for a meter on the old stone panels... but I seemed to get all the 'good' unique jobs that turned up.
this is what Anakin was talking about when he said he doesn't like sand
Turned him into a right little devil
"I don't know if they changed terminology since, they do that quite a lot"
Well, at least basic components like condensers won't change.
Wait...
Here in the US we just call them 'fusible disconnects'.
You bloody well would?😂
Should you order "chips" or "fries"? Rent a "truck" or a "lorry"? Stand in "line" or "queue"?
Anything can be fusable with enough power...
@@groovejet33 if you get lonely you can dress up your carriages in boots and bonnets and take them out for a jaunt
Everyone's a bloody comedian 😂😂😂🤣🤣🤣
@@groovejet33 See we 'Mericans are simple folk. We don't call our chips crisps, nor our fries chips. The only queues we have are sweet and we don't name out trucks Larry. Honestly, what's with you British folk calling every truck Larry? He a local legend or somethin'?
All I know about electricity is enough to be dangerous lol. I wish you did a video for unknowing people about how to use a multimeter without burning it up. I'm not always sure what to set it on. I'll never forget your video on shaving with a funnel.
don't worry, some of us have been using meters for many years since childhood and still blow them up on occasion. I've sent plenty to meter heaven over the years, including vacuum tube models, which I still own some of.
My general rule at work is never throw away anything mechanical/ electrical without taking it apart first. I started to do this as a kid.
My brother in law's favourite saying; If it's not broke, don't fix it.
I was at an event helping with sound and they brought in their own homemade distro which required manual tie and a 40 amp two pole breaker. Apparently it wasn't working right and they had to get a new one prior to me getting there. At the end of the day when they uninstalled everything they were going to throw away the bad breaker and we're wondering how it worked and what might be wrong with it, I'm like no way I'll take that and said I have taken apart a single pole breakers but not a double pole that thing will be apart faster than....
curiosity and thirst for knowledge. it's still the best way to learn many things or the fallacy of them ;)
"Detective Clive at your service. Ralfy, we have a new case to solve..."
Now I want mikeselectricsstuff to blow an HRC fuse with an enormous overcurrent and see if it really doesn't blow up. Would probably be quite anticlimactic, but interesting nonetheless.
I wish consumer light switches were available with that kind of umpf. I prefer this kind of tactile feedback to e.g. touch switches.
Ok, that's really cool. The huge spring in the actuator makes sure the contacts close really FAST, but the little spring makes sure they don't close HARD. Do you thing it was running hot enough to distort the spring without messing up the adjacent metal?
It looks as though the spring took the full load. The adjacent metal wasn't obviously overheated.
@@bigclivedotcom Yeah, I posted my comment before you discovered the sand. I should wait till the end of the video before commenting... Astonishing how just a tiny bit of debris knocked out the whole thing.
I don't think they care about contacting hard, The small spring would just allow tolerance in the range of motion of the device (pin arm push assemblies like that are terrible for maintaining tight tolerances in the final position of the end of the contact), so they can have error/wear in the assembly but still make proper contact/disconnection. But you are right about the spring cartridge in the back causing a hard fast snap to bring ALL contacts together with as little as possible time to arc and timing variance between making connection between the legs. Maybe also causes the contacts to separate in a speedy manner as well to limit arcing.
@@Tom89194 I figure that repeated hard contacts might flatten or damage them, although that might be a good thing, if it had closed hard, the sand might not have affected it.
I thought that was a zoomed in shot until your hand came into frame. That breaker is massive.
It's a tiny little baby 660V 63A 3phase Fuse Switch. Seriously... it's very small.
Excellent deductive reasoning. The best days at work are figuring out why something failed, but it is also someone else's problem to put it back together.
Oh boy when Clive breaks out the gloves you know it's serious
I watch some hvac channels and sand in disconnects, contactors and time clocks is a killer. It takes just one grain in right place.
Yeah, it jams gears solid.
Sand in contacts, or dead (dry) insects can and does cause faults. Sand in mechanical components is even worse, especially if it contaminates the grease or oil that is supposed to lubricate moving parts like gears or bearings...
@@Mark1024MAK The dead insect in a relay contact was supposed to be the origin of 'bugs' in computer code. The original 'bug' was supposed to be a dead insect that stopped one of the electromechanical code breakers working at Bletchley Park in WW2. Someone found it and held it up with a pair of tweezers and announced the problem is a bug.
@@johnmurrell3175 - yeah, absolutely. I’ve also had it myself with electro-mechanical equipment that uses electrical contacts. It doesn’t happen very often. But occasionally an insect or similar will get inside the equipment casing and then at some stage the contacts will close. If it’s in the way, it will be trapped, and the contacts may not make properly, hence causing a fault.
And electronic solid state systems are not immune to the problems of nature causing havoc. One failure of a system was due to a slug moving across some 240V PCB tracks, then dying. Then the gunk corroded the PCB tracks which caused a failure...
@@johnmurrell3175 That folk etymology is not correct. Bug was used as slang for a problem in engineering since the 19th century.
Fusible springs are new to me...
I really appreciate your videos. I've been binge watching them for the last couple of weeks and am completely fascinated by your knowledge, so much so that I bought a soldering kit, have made a lamp, modified some LED bulbs, and have a nixie tube clock kit on order. Thank you for what you do!
In the old days, at least in the USA there was a different philosophy, the equipment was designed to take a full fault and remain in service with just a fuse change.. and the fuses are all rated at 200KAIC. When I first encountered ICE components I was shocked that the design philosophy was that it did contain the fault but at the expense of itself and half the the equipment it located in.. We had and still have plenty of crappy designs but Fused Disconnects are particularly hardy.
NEMA OVER IEC all the way! Give me Any Square D or Allan Bradley NEMA rated motor starter or contactor any day! IEC Inferior European Crap! I deal with that stuff every day modifying so they meet CSA and Ontario ESA standards. From fuse holders to contactors and many cases design issues from grounding and bonding to the misuse of auto transformers instead of step down transformers, just simple build quality when it comes to electrical
@@carlubambi5541 Agreed on the NEMA and UL standards but take it from me (someone who has sold over 200 million in electrical equipment over the last 40 years) SqD and the other US manufacturers are a ghost of their former self.. Most are to owned by US companies and are not taken seriously by their parent companies.
Allen Bradley (now owned by Honeywell) is still a quality oriented company..
The new moto for these formerly great companies. NOT ENOUGH MONEY TO DO IT RIGHT, PLENTY OF MONEY TO DO IT TWICE!!
Another source for contamination are metal parts that has been stone tumbled to take the biting edges of stamped parts, the stones would of course wear to sand in time. The small parts manufacturer are sometimes sloppy in the clean up and the assembly people just didn't notice. The sand would have dried/caked in crevices, and then loosen with the rattle of the spring loaded mechanism.
In all the years i have been repairing stuff,i still get a buzz of achieving it (no pun intended) like my mate Vince does,even though i'm a computer technician.
Your videos are excellent, enjoy watching them so much. Also always listening out for 'one moment please' :D
I now unconsciously say the exact same thing when dealing with a problem requiring a few more moments thought. Wills never get the BC Accent though!
I was always taught that a switch-fuse is a combined isolating switch with a fuse affter it, the fuse being permanently connected to the output
A fused-switch is like the MEM (the ones you can remove the carriers) switches where the fuse carrier moves and makes contact both ends, so when it's turned off, the fuses are disconnected totally
Not sure how that one would be specified, but closer to fused switch
"That's probably a failure mode they didn't expect."
I'm sure they will thank you for finding this one. I wonder who they'll fire- someone in design, or in shipping?
We call them CFS units here in Straya.
Combination fuse switch.
Best to pull them apart when they are closed, the springs less “hurty”.
I always find it funny how they sell phases in lots of three, and fusses in packs of ten.
Just like watching cars race at the track, there's no skipping ahead or pausing the video if there's a chance of blood, injury or death that we might miss out on. A simple guiding principle for RUclips video production.
Clive is usually nice enough to inform us of any blood with a parentheses in the title.
First thing I said when I had the factory tour at my current job was have you exercised you're breakers on the subs. Seen too many factories where it's never done and when needed the pneumatic breakers don't work after many years of sitting idle...when they had it tested it had indeed failed... luckily they had the sense to get the dno on site ready in case of a problem.
I just plugged my phone in to watch the video and the g1000 charger for my Google pixel went pop. Took it apart and found a distinct poop stain on the inside and capacitor guts sprayed about in the case. Lost a good soul today.
Why does europe use currents like 63 amps for this specific instance and 32 for a ring main in the house. Why not use round numbers like 30 and 60 or 65 like you'd see commonly in the US
I think the currents were based on standard cable sizes.
Round numbers are hard to mount, the slightest tilt and they roll of into the most difficult places, so when youu need 60 they include an extra 3. "/
@@snakezdewiggle6084 Smarta**
It's clearly a calculated size.
One answer is that you should not be able to run a fused network on the edge by using 2x32amp fuses on a 63(64) amp fused main. So you can add only use a 16 amp fuse and or 6/10 ones and still have a security margin to not overload the wires and contacts. That's why there are odd numbers. A security precaution.
Excellent autopsy! Thanks Clive and Richard.
When in doubt, put on gloves and remove all the screws.
I find myself looking for the Explosion Containment Pie Dish, even if nothing will explode, it would also be handy to capture liquids.
4:45 "If you just wrap a bit of wire round here..." you should be fired and never employed as an electrician again. Has someone really done that? What did they think the fscking fuse was FOR????
It's horribly common due to the ongoing deskilling. The labour doesn't even understand the concept of an HRC fuse or arc flash.
It is common for a handyman or groundskeeper to try simple things like replacing fuses. So i can imagine what has happened with some that just want to get it working.
MacGyver does it with chewing gum wrapper.
It was very common when residential distribution boxes used actual fuses instead of sealed circuit breakers.
Terrible and dangerous practice. I hope no one even thinks about that in industrial setting. That's how you cause all kinds of havoc and more than likely kill people.
@@andreasu.3546 yeah after reading that i remember watching that as a kid.
Loosing a neutral is always fun when it turns into a star point!
I must admit I am quite fascinated by really high current gear. We are having a new machine line installed at work and they have just had about 20 people in to pull through a great big fcuk off SWA cable the size of my thigh from the substation along the cable trays suspended from the roof! You should have seen the size of the drum it came on! Was talking to one of the guys who looks after our substation and he was saying when they liven up really big stuff they don a flash suit that wouldn't look out of place on an episode of Captain Scarlet, stand off to one side and then twat the breaker with a long big of wood! When you are playing with power levels above a certain level it's not the electricity that gets you, it's the flash and the bang!
I mean the electrical load just for the *lighting* in one of the machine halls is probably about 40kw... God knows how much the total load for the whole site with all the machinery is!
Having installed similar cables I don't recommend it for fun.
It would be interesting to cut / break one of the fuses open to see if the sand in the fuses is similar. The 'snap' action is required to minimise the contact arcing as they are opened or closed..
As an aside Lifts are quite interesting as electrical loads as they regenerate when the control system controls the lift speed when it is imbalanced. We had a couple of lifts that caused problems due to this - one the electricity meter (rotating disc type) went backwards when the lift regenerated and it got very confused about the power consumption. In another case there is a station that has 4 AC lifts on a feeder from the street supply. When the lifts got into phase so most of them regenerated at the same time the voltage to the local shops went above the normal supply limits ! In normal buildings you do not see this as the lift power is only a small fraction of the building consumption. However in the two cases above a new feeder was put in just to supply the lifts the other supplies for the station being derived from other sources.
As a Sparky from Australia I would describe that as a CFS unit. With CFS standing for combined fuse switch.
The small springs that put pressure on the contacts likely overheated from poor electrical continuity between the main arm and contacts letting excess current go through the spring. I've replaced micro-switches that failed in a similar manner - poor contact between the common post and the switch arm causing current to go through the snap-action spring, causing the spring to overheat and lose its springiness. The loss of contact during mechanical movement does not need to last long for enough inrush current to overheat springs.
Thanks for reiterating exactly what Clive said.
@@xenonram Wrote that before reaching the end of the video. Ideally, that thing should have had braided copper crimped or welded between moving pieces to guarantee a good chunk of the maximum allowed fuse rating and prevent arcing/pitting/welding between moving parts.
I am disappointed, you didn't turn it to make the loud sound, and you didn't crack open a fuse!
If spring was loose it may have been arcing and heating up that way?
Hay Clive - you play with ionizers - youtube search this video title by - the action lab -( These Planes Are Propelled With Ionic Thrust ) it might interest you.
hahahahaha i was nervous about the spring the entire time, even with the glove on.
We call them fused disconnects or rotary disconnects now.
Dumpster diving got me 2 old alarm clocks made in the uk and Scotland. If nobody want em on eBay you interested in them for a tear down?
They might also be of interest to Fran Blanche (franlab)
Big switches like that used to have spot welded braid wire to the moving contact. This switch is missing the current carrying braid, so the current can travel the piviot and spring, resulting in heating of the support components. If the spring was on an insulator to prevent it's heating from current conduction, the other higher resistance points would have heated instead. The spring failed and the contact opened. The spring should not be a current carrying component in the switch. A low resistance path around the spring is lacking.
.........and on the fuse replacement subject; you absolutely must, in every circumstance with three phase loads, replace all three fuses as a set!
Thank you Clive!
Remembering old English Electric switch fuse manufactured in India on late 80’with different mechanisms.. toggling mechanism will be bulky and robust , and actuating rod will passes through the fuse module with double break for neutral too. Not like yours toggling mechanism extends under fuse module
If the spring was passing current, which it looks like it was, it would probably melt pretty fast. It wouldn't take a lot of current to melt that. When I was a teenager, one time I was playing around with a spring and connected it to a low voltage supply to see if I could get it to glow. It was a relatively thin spring and within a few seconds, it was glowing red hot. After it cooled down, I noticed it had lost its springiness. When I stretched it out, it no longer popped back into its original shape. I'm not sure what the heat did to it to cause that.
The old stuff you see now is more reliable and easier to service. The old stuff that wasn't got replaced.
I wonder how much of how hard the thing is to engage and disengage is the result of just having a long actuator that doesn't necessarily line up ideally with all the modules.
That reminds me of a similar case in a very different appliance. I replaced a blown 3 A fuse inside a 12 V cigar lighter plug by a 12 A one because I did not have any other of this size. It was only for a short test with short periods of maybe 6 amps. Suddenly the current was broken and I wondered why the 12 A fuse should have blown. Further investigation showed that the spring holding the fuse in place did not like those amounts of current and got so hot that it melted the plastic nearby. This resulted in the relaxation of the spring thus loss of contact pressure pretending a blown fuse.
I once was (at first) blamed for what turned out to be a "tired" fuse when one blew in the disconnect feeding my portable distros and dimmer rack during a load-in.
It somehow instantly took out the entire building as well, which wasn't good in a hockey arena during -30F weather. It got cold inside, but not too cold to ruin anything before it was all back up.
Cold seems like a good thing in a hockey arena in my mind 😉
@@oliverer3 thank you that's what I was going to comment. Yeah I always suspected of house electrics. It's the number one thing I can't test enough.
This reminds me of the old Lever 2000 soap commercial.
"Best for all your 2000 parts."
If that was what a grain of sand can do, how much damage would half a grain do? And if you keep halving the grains, at what point do they stop being grains, and do they still cause damage?
Half a grain of sand is just a smaller grain, so you can just keep going. I'd suggest you stop somewhere before you reach atomic silicon, though, because that could cause quite a bit more damage than you'd expect from a tiny bit of sand.
Cheers Big Clive,
Wait; I was waiting for you to put the bits back together.
Maybe next week?
Cheers,
Clive: Puts unit back together. Builds a small lawn mower with the bits left over.
Dear God of Bloody Fingers! At last! Clive is wearing gloves! :D
"you hit the nail on the head" with the failure diagnosis, which probably stemmed from a phase loss and slow cooking fuses in the past. when slow cooked they tend to be real brittle and will shatter when replacing, dumping their shmoo everywhere. lol
A possible durability upgrade would be to use an nylon leaf/wishbone spring, or spring with insulation at one end so it cannot be the electrical connection. Then if something like that happens, the assembly might make proper contact after cycling the mechanism. This is unlikely to work if a spring meant to ensure the contacts touch as intended no longer functions:)
It's all fun and games until you see plasma.
Fill them with water and freeze them before taking apart.
Paraffin sounds like a better idea.
No matter how good the 'rocking' contact connection is, the spring will take some small current. All of the springs I could see in the video looked a bit corroded. So if they're the wrong type of metal, as I suspect, the springs would be subject to electrolytic corrosion. Any heat from the high current would just make it corrode faster.
Not in the industrial application, but I remember bits of card with different fuse wires wrapped them, for the home. Then if the fuse blew, you simply picked out the right wire (well hopefully right wire) wrapped it on the post and off you went again.
Yeah, as I kid in the UK I remember that as well. And I was always putting plugs on appliances. They cam without back then.
Featured in an older video on this channel.
You can still buy fuse wire cards:-
cpc.farnell.com/pro-elec/fusewire/fusewire-5a-15a-30a/dp/PL09979?st=fuse%20wire%20card
Whenever I dismantle a complex bit of apparatus,
I often wonder 'How in the heck was this assembled at the factory'.
It's almost like the butterfly effect: A bit of grit leaks from a fuse, and corrupts a contact that overheats a spring, which causes the switch to fail, which causes the lift to come to a halt...
In the tower that Jack built.😁
HRC fuses were THE best safety improvement over the old domestic rewireable ceramic carriers. Removed the temptation to replace the blown fuse wire with random paperclips (my Grandfather's speciality!) I've got 50A DIIN HRC carriers in both banks of our home distribution board, as a "last ditch protection" strategy should any fault current exceed the (already good) breaking capacities of our RCBOs. If the fault current exceeds the 80kA break capacity of the HRC elements, I think that'll be the least of our problems! :-)
I've never measured a Ze value low enough to cause a fault current more than about 3 kA. I poke my test meter into mainly single-phase supplies in the suburbs of a large UK city, but occasionally 3-phase supplies as well. I've never had to specify circuit breakers with more than the standard 6 kA breaking capacity.
I think even the old BS 3036 semi-enclosed fuses are good for 3 kA as long as there's a suitable cut-out fuse upstream - there's a table in BS 7671 somewhere.
I've seen big HRC switch-fuses in circuits where maximum fault current is 1 or 2 kA, and never understood why a little MCB wouldn't have sufficed.
@@westinthewest The only situation where such a high prospective fault current might arise would be from a significant supply over-voltage, and that's all but impossible (even in rural Australia). It is always impressive how an 18mm wide MCB can handle many kA of fault current, and sometimes they survive (i.e. can be reused until a replacement arrives!)
There's a lot of little subtleties in that switch design that I think you're overlooking. If you notice the center hub actually turns a little bit past the center line so it's actually has a toggle action. There is a spring resistance when you twist it back that it you have to overcome before you break the circuit.
The other interesting thing is that it is obviously designed to apply direct force to breaking contact. The pressure applied to the contacts to make contact is limited by that spring, but you've got a direct mechanical linkage that goes from the contact to that arm to the hub and then out the side to the switch lever that allows you to apply great force to make that thing separate. Usually contacts just get separated by a little spring, there's not that sort of direct mechanical means to apply force.
Yes, over centre lever action.
You don't understand that the main priority with that action is to OPEN the contacts as fast as possible... using that snap action.
Closing is much less an issue - make .. not a break that creates and arc.
These are made to open or close under 'on load' conditions, so that fast snap action is needed.
Same principle in home light switches... why they should click.... and why the higher amp rated ones click louder.
These thump open and closed.
Pause the video? No way. The narrative during disassembly is always entertaining, especially with the r-r-r-risk of impalement!
Could the sand just be from the environment the elevator is in (like a beachfront property like a resort) and has caused light/intermittent internal arcing between the contacts, thus melting the spring?
Arcing on the contacts would've been visible on the main mating surface, it'd have gone sooty.
It was a very fine sand identical to that found in HRC fuses.
When I was an apprentice, we were taught to push down and bend the end tab to signify the fuse had blown.
would this be the switch an elevator technician operates to completely starve it of power to be able to work on it ?
Yes, although there may also be local isolation in the panel.
I do believe the Scott Manley of EE is more Manely than any of us could ever conceive
I really really enjoy the way your brain diagnoses electronic issues Clive. I am not a electrician in any way, shape or form - I'm a student studying Conservation and Environmental Management. The way you look at electronics is the way I look at ecosystems - trying to trace back to that one part that stopped working. Your videos inspire me to think differently about things, being on the spectrum it's easy for me to "A+B must = C". So thank you for sharing your process mate, it's a fine art my friend. 👍🧠
open neutral is a bad thing indeed
i learned that the hard way
2 phases loaded with fluorescent tubes fittings with power ratio compensation (old magnetic balasy and series capacitor for 2nd lamp in the fitting)
3rd phase only got someswitching power suplies
let's just say i turn on the lights and they were flashing randomly but louder and louder then something exploded behind me
and it wasn't a small overload since those 2 circuit with compensation normally takes 8 amps each (they did take 16 without compensation before)
and is that fused switch comparable to those panel fused switches you load with small ceramic fuses and they make a blade to blade contact inside when you close them they are like quick disconect you pull on a handle down pulling all the fuses in cartriches out along with the handle something like this one lh3.googleusercontent.com/proxy/nDE7Ke7tQDl7M1O3XAHs-EoAfp8Db_Krmm2p7KgFUestvoyHmP1LbswM1_5_SDMnGJJWUFxMri4DQkxbKCwaGC1gYoAHbsLWyOq_qnd9P7yhfHdPfRFiyznhH_SUpW5oLJAX3bDV
or is mechanical switch somehow superior to those cartridge fused switches?
"knocking power out to buildings"
Even worse is when the fault *doesn't* knock the power out. I've seen the pictures where neither the 400A breaker nor the 2000A upstream breaker tripped and current continued to flow into a hard fault until the power company showed up and killed power at the transformers. Not pretty.
I had that at a factory where the factory "hero" had progressively bridged out every layer of fuse protection.
10:40 left hand side where burnt spring is... open hole beside bolt holding fuse.... If the assembly was mounted horizontally then any silica from a blown fuse would happily be funneled down to that suspect contact... from the hole, around the plastic case screw thru-hole, and down the slope of conductor straight to the spring and contact... Would love to know how the assembly was mounted or if the spec sheet demands vertical mounting
A blown fuse should not really physically break. I think this unit had sand in it from installation or a shipping incident.
Knowing when not to go bareback. Priceless.
I barely understand most of what you talk about but your troubleshooting abilities are second to none. You have so much experience in electrical work its just mesmerizing to watch you diagnose an issue and find the problem with such high levels of accuracy. Bravo mate!
forensic clive finds springy fuse! Thanks it was interesting.
Hope the elevator didn't crash to the basement. That would be funny and get lots of youtube views. Only kidding.
As exciting as that would be, the loss of a phase should theoretically shut the elevator down and drop the brake.
If the brake didn't apply and the motor tripped then the bias would usually be for an empty of part loaded elevator to go to the top of the shaft due to the counterweight being balanced for half load.
@@bigclivedotcom I live in a high rise. I have every confidence in the ThysenKruppt German engineering. Apparently the lift can hold its own from one steel wire strand as opposed to the 5 installed. Tom Scott on RUclips visited their factory and they use magnets 🧲 now. This allows a 2D or even 3D lift mechanism. Crazy. Watch all you videos. Flew Dan Air turbo props to IOM for my first holiday in the 70's. Flew from Newcastle. You could smoke on board then but I was only 9 so got wrong :)
@I E Otis did the system for the original tower of terror. It's very complex to be able to drop faster than gravity.
No that's over stripping the insulation then ramming it into the switch !
Had one of these very badly burnt out at work on cooling fan a transmission transformer.
Hi Clive, id there any chance of "doing a vid" on fault current and prospective fault current. I've been trying to find out what the fault current of a dead short might be in a 240 volt domestic environment, purely for academic interest. When I did my 16th Edition and Inspection and Testing exams I couldn't get to the bottom of it satisfactorily. Thanks.
I really should do a video about that. Particularly the increasingly pointless tests and paperwork being invented by the paperwork "electricians".
Complicated answer: Short circuits are describe as having 3 components. Sub-transient, Transient and synchronous (steady state). as a protection guy we are most interested in transient and steady state. Only if we are electrically close to a generator do we consider sub-transient. Not going to do a system analysis course here tho. In domestic systems here in US, short cut currents may be in the range of 500 to 2000 amps tho the panel breakers may be rated 10,000 amps.
Maybe a sudden surge of too high a current melted the spring. Maybe the equivalent of a DC to DC converter for high currents is needed so that doesn't happen again? If this is what happened, the fuse blew a second or two too late.
The spring's not supposed to be passing any current at all. It only was because the sand was blocking the proper contact. Just normal usage under those conditions was sufficient to melt the spring, no surge needed.
Just sat on the porcelain throne, and this notification popped up. How perfect.
how is this reply 4 days old ? when it came out today wtf
@@danielhorne6042 he is a patron & gets videos earlier than us peasants
In our household we used call it the bog pot! Or sometimes, just Thomas, after Thomas Crapper.
Lift or elevator?
A man walks in to a London Hotel. An American guest walks to the lift. He shouts "hold the elevator". The staff member goes "we call them lifts outside of America".
The American goes "we invented them, so we call the elevators"
The staff member wittily replies "yes sir, you did, but we invented English"
Technically lift is properly correct as you are "lifted". Elevation is a static height, like mountain.
I will get my coat.
No sliding contacts. That's the weaker construction, also when used in corrosive environments like paper mills.
The ones we sell have knife contacts sliding between a springed fork. Wipes clean at every action. Will not try to disengage on short circuit, cannot bounce. 100kA @690V rated.
Interesting! I've never seen such a combination in the Netherlands before. I can only relate to fuse-disconnects that have the fuses (we call them knife-fuses) clamped into a cover that one pulls open to break the circuit if needed (and of course pushes shut again when power needs to be restored)
Switches are always single parts added when breaking the circuit by actually removing the fuses isn't such a good idea anymore (I think above 63 Amps) or (probably) when the fault-current exceeds a certain value (when the switch-cabinet is located close to the transformer and the circuit before thus has a very low impedance)
Fault investigation is always fun. The last case I came across was a tripped breaker from a short circuit. I determined the root cause to be a stray metal object bridging the exposed live and ground on a regular American 15A power plug. Our plugs really are the worst, almost every other country's plugs are made so you can't contact live pins.