Hello! One thing I didn't touch on here was the power draw of the contactor itself. For the contactors I'm showing here it's quite small (just a few watts) but there are some applications where a latching contactor may be desired. These have two magnets - one to close the contactor, and another to release it. These can save some energy, but come with the risk that a control system failure may leave the contactor engaged. Depending on the application, that could be _very bad_ so they're far less common.
You could have a collapsible circuit on the disconnecting coil, so if power is lost a capacitor discharges through the disconnect coil, adding a fail-safe mode.
I just want to say as an hvac technician your channel has been invaluable for showing less tech minded coworkers breakdowns for things we touch everyday. Your refrigeration episodes genuinely get pulled up very often
@@ClosestNearUtopia I'm not 100% what you're trying to ask but you're asking what I have studied, I have a degree in industrial electrical, including PLC, analog controls, solar, and instrumentation
5:20 fun fact, this is also a major reason why restoring power after a blackout is trickier than you'd think. If you restore too much coverage at once, everything that's plugged in will restart and momentarily draw startup current at the same time, which runs the serious risk of blacking the grid right back out again.
Short version: Electromagnets control a physical conductive switch. The end. HVAC Trivia Version: hey did you know that connecting these two 24v wires on my thermostat triggers the AC to go on?
@@randomblock1_ Correction, rewatch the video- thats 24vac from the supply transformer in the airhandler unit. And in a modern smart thermostat the 24vac is rectified to either 3.3vdc or 5vdc logic power to run the control board. The little click sounds you hear from that thermostat are from the micro-relays that switch that 24vac as signals to control the airhandler blower and outside compressor units. Much going on under the hood, to most users its just magic stuff that works, ideally.😊
@@KevinSmith-ys3mh Some low end electronic thermostats still use AAA batteries, that need to be periodically changed, but that's still worth it for the energy savings.
@@buddyclem7328 yeah, I hate those things, they are a servicing call waiting to happen when the next owner moves in, the manual is in a junk box or trashcan, and the batteries are leaking and corrosion all over. They should at least use 10 year life lithium packs like new smoke detectors, and have legible labels on it to inform the users. They are mostly a replacement for the older round mercury switch dumb thermostats and to avoid pulling newer 6-8 wire cabling. With any luck in the next generation systems they will move to fully digital wireless connectivity & controls and wiring problems will disappear! 🙏🤗 Better control systems are possible for a reasonable price now, saw one on the "this old house" tv series recently that a typical DIY guy could buy as a kit and install! The problem with change isn't hardware, it's the hidebound mindsets of companies and installers. 🙄
yup, covered the wiring better than my instructors did at school. Just a 2 day module cause we were going into factory maintenance. Still better than what I paid for.
@@Raeilgunne Having not gone to school for HVAC but being in the field, I would definitely show this video and his previous videos on heat pumps etc to new techs. Installers, maintenance and service techs can all learn a great deal from these videos
Having worked in Industrial Controls, his lack of PPE would caution me from showing the footage in a learning environment (when taking voltage measurements at the HVAC unit), as it would set a unwanted precedence. Safety First, even if it is just 120VAC. The lack of proper PPE when working on live voltages over 50 Volts would have resulted in his immediate termination at any of my former employers.
One common criticism in movies is that stadium lights don't actually make that "chunk" sound when they come on. But a warehouse I used to manage used contractors to control the lights, and they made the most satisfying "chunk" sound when activated.
Two stadiums where I have switched lights do make that clunk, but it is in the utility room usually far away from the switch being flipped. They use contactors. One of the stadiums used several contactors with a little box that sequentially turned them on about 1/2-1s apart to avoid a huge starting surge.
Did the lights come on in sequence, each with their own 'chunk' noise, in order to dramatically reveal the alien spaceship or high-tech fighter jet that was in the warehouse?
Hahaha just image being in a power distribution room and toggling over 20 medium voltage contactors/switch's/connect barrs etc in sequence, you feel your body shiver
As an electrician that works mostly in commercial and industrial jobsites I appreciate the way you can explain something so simply anyone could understand like an apprentice. I will use this as a reference when explaining these to those apprentices who just don't seem to get what I'm saying
@@epistemophiliac5334 I still like watching this channel even though I know all this stuff… If you want a simple explanation for more complex electrical, go watch a guy named Dave Gordon… While I understand electrical systems as I started as a computer engineering major before switching to computer science, I cannot explain things anywhere close to Gordon… Particularly useful if you work with three phase in industrial applications…
I worked for a low voltage company at one point and had access to the elevator room in an old skyscraper. It was literally an entire room filled with contactors. Probably hundreds of contactors big and small just click clacking away as people would call and use the elevator. It was a very impressive show and mesmerizing to watch.
So you're not "cut out" for one minute videos-big deal. Your 20-minute videos do a really good job of not only explaining how something works, but why it needs to work that way (or how it could work better.) And you make them interesting to listen to. I spent a decade as a corporate trainer, and I understand that's it's not easy to put all that together
Well there's currently 441k people so far who watched a 24 minute long video on a fancy electric switch, so maybe we're not cut out for watching one minute videos too :P
Unfortunately, while this is totally true, youtube has changed their algorithm because they're afraid of tiktok, and now creators that do not also publish 'shorts' are penalized in the algorithm. So if you care about growing your channel, you too must dance.
I just finished watching a video by Logically Answered about how shorts aren't profitable enough and now platforms are starting to move away from them, so it probably won't matter in a year.
One thing you mentioned when contrasting the contactors with relays is that they don't have normally closed contacts. In the field of industrial automation, it's actually very common for them to have additional normally closed contacts, either in the form of a 4th pole that's normally closed, or an auxiliary, low-current contact block that gets attached to the contactor. The purpose of these is to allow detection of welded contacts, as if one of the contacts welds closed, the normally closed contact won't close when the coil is de-energized. I have some old leftover ones lying around that I could send for a connextras video if you're interested!
I have a welded motor starter contactor that I keep on my desk as an example just in case someone tries to save money by eliminating monitoring of the aux contacts
Contactors with loads of "auxiliary contacts" that can be either NC or NO are common in old electric locomotives: e.g. the main traction-wire-to-internal-HV-bus contactor has auxiliary contacts that take part in its self-sustaining, and various contactors that connect various arrangements of engines to the bus have auxiliary contacts that allow other contactors to be powered.
Those Aux contacts are also REALLY common in industrial facilities for switching auxilarly items, such as indication lights, status to a Control system, providing "seal-in" functionality where only a momentary start/stop is required to start/stop the motor, and opening solenoids for cooling water loops, valves, or closing an aditional contactor to run oil pumps, or other auxilarly items.
@@chaos.corner I honestly can't think of a relay I have seen that is single pole in a modern relay. It can even be hard to find one thats just a single output, so many are dual pole dual throw. I think the only place I have seen single pole relays are the automotive world, where they are trying to shrink them down so much to fit in a tiny electronics box.
I spent a summer as a brakeman on a short-line raiiroad. I had a big "aha" moment here when Alec mentioned the "gnarly" contactors on locomotives. Suddenly, the big loud click that happened when the locomotive was put into dynamic braking made all kinda sense. Thanks, Alec!
I am so proud of you for referring to a meter which is set to current mode as a jumper wire. It can be hard to make people understand why current meters must always be connected in series with the load to prevent bad things from happening. Comparing the meter to a jumper wire gives the user a proper mind set as to what they are doing if they connect an ammeter across a source or a load. I think the ready availability of clamp-on meters these days is making life a lot safer for electrical workers and experimenters.
The other day I shorted out a battery I was testing and immediately checked over the meter to see if I had left it in current mode or something. Nope, it was set to voltage and the leads were in the right place. So I set a different meter to continuity mode and probed the leads, and sure enough, they were shorted. I opened the meter up to see if something was broken and discovered that the shunt that bridges the common and amp jacks was totally uninsulated and travelled directly below the volt jack, so a standard banana plug inserted into the volt jack could touch it and short out. Moral of the story: anything is better than the $5 harbor freight multimeter
It's also good to note that a volt meter will also work as a jumper if the internal resistance is too small. My electronics instructor liked to remind us of that fact with the story of a field tech he knew. The guy used his cheapo meter to test some connection and it basically shorted the contacts. That caused a massive door/vent in a hydro dam to move enough to potentially cause serious harm to someone. (there also might have been an explosion(?), can't quite remember) Luckily no one was injured, but that guy certainly lost his job and possibly entire career. Suffice to say, that spooked me well enough to only buy decent meters. Plus "buy once, cry once" y'know?
@@SplittingEagle1 an unrelated hydro dam story I've heard is where someone connected the generators to the grid while the phases were 180 degrees out of sync (didn't read the display correctly?) and the entire generator was ripped out of it's housing
There's a room where I work that has a normal light switch to turn on about a dozen massive light fixtures with 80 incandescent light bulbs each. When you flip the switch, you can hear the massive *ka-chunk* of the contactor from behind two walls a hundred feet away. I've sat there for more time than I care to admit just flipping it back and forth because it sounds so neat. Thanks for the insight into the mechanism!
The really big ones use timers so they won't all turn on at once, to manage the inrush current. That's why you get some giant buildings that make the clunk-clunk-clunk noise, each clunk turning on another bank of lights.
Same! Not quite as extreme, but I always enjoyed turning on the exhaust hood at a kitchen I worked in. You'd simultaneously hear the contactor, the fan motors lurching on, and the removable louver panels jostling a tiny bit as the fans made a big enough pressure differential to lift them against gravity.
@@vylbird8014 Ah, I guess that also explains the TV and movie trope of the long hallway or ominous warehouse with lights turning on one section at a time.
@@dfiekowsky Makes great TV, yes. But many large buildings did that. This was back when incandescents ruled though - they have a really high initial current, just for a fraction of a second, so if you turned them all on at once you'd trip a breaker. With modern LED lighting, not such an issue.
@@MPI1000 yep the bigger stuff is way more interesting imo. Deal with it frequently at work with large refrigeration compressors. 300hp motors just use vfds more often than not to better control inrush. But they also have bypass contactors to deal with vfd faults.
I really do enjoy your videos. This one brings back so many memories. 1. Like when the contactor for the vacuum chamber exploded and threw mercury into the local environment (me!) To prevent contact burns some contactors use a simple plunge into a pool of mercury. Oops! 2. I once met a gentleman who used to work at Stanford Linear Accelerator (SLAC). One day he went outside because he heard a strange noise. Someone had forgotten to crank open the contactors in the beam line. There was a 6 ft arc coming from a piece of equipment into the local earth ground. Yes, arcing into the local soil with all the crackling, smoking and such that that infers. After some time the subsatation contactors opened to break the current. Apparently it was pretty spectacular. After that experience he thought that a career in retail sales of low voltage electronics was a probably safer choice. 3. At one laser manufacturer I worked at the assemblers of the power supply (15 kW) would sometimes wire in the large capacitors backwards. In test of the laser, that capacitor would heat up and there would be a steam explosion that would dent and deform the steel cabinet. Then the transistor pass-bank would arc out, causing the power company pole transformer to explode, and then they would come and lecture us on being more careful. Mostly we just learned where NOT to park - no by THAT pole. Such Happy memories!
I had an internship at an electric company which mostly builds distribution cabinets for high power applications. They had huge contactors that had a wind up spring that when engaged slammed the contacts together. You could feel the impact in the floor you were standing on.
Actually those are usually classed as circuit breakers. :) Probably ACBs, Air Circuit Breaker. They come in many variations, with for example a manually pumped spring, or motor operated, with electrical on and off coils, or manual mechanical buttons, under volage relase, with or without built-in protection relay, and more.
I test protection relays and the VCBs (vacuum circuit breakers) protected by them. 12kV breakers still make me jump when they trip. I’m currently working on a system with 345kV breakers and you can feel the ground shake across the yard.
No it's actually just a simple wall switch they can handle the same amount of electricity as your average American home (somebody's made it for some reason we all know this)
Industrial lighting systems us rotary latching contactors in a central lighting control panel. The wall switch in your office or hallway is a low voltage device - generally under 24VAC - that signals the lighting control panel. These systems are frequently integrated with broader building automation systems controlling HVAC systems. Modern systems often use digital signals to perform the signaling function.
So, just as a counter example. I used to work for a huge arcade (I think one of the largest in the US actually). All those games are shut off every night to preserve power. One of my many jobs there was to go to the bank of circuit breaker panels (not just breakers, I think there were 6 separate full height panels full of breakers) and manually flip off all the breakers one by one (actually 2 by 2 in the morning once you got good at it) to shut the whole thing off. And if I worked morning shift, same thing in reverse about an hour before opening. No contactor, just on the order of 100+ switches that had to be flipped. That said, I also got to work with the mother of all contactors, the one that controlled the whole building. I honestly don't actually know if it was a contactor or a giant breaker, but there were a couple scenarios when I had to literally shut off the building and got to flip the tiny switch next to the massive switch in the main electric room. That thing was the size of a basketball and god was it loud when you turned it on as the two giant arms of copper slammed down.
@@JohnR31415 there is really only one major company in the US/Canada that does DALI, most companies have a proprietary way of communicating with their relays in a distributed fashion. I commented on the main video about the different lighting controls manufacturers who provide that control to all buildings in Canada and the US. (required by code to have automatic control now in pretty much all jurisdiction). Typically you have one master LCU (lighting control unit) or brain of the system which takes in a ton of low voltage inputs from the system (think switches, daylight sensors, occupancy detectors, etc) and decide what relays to turn on/off depending on programming. There is also the whole dimming side of things (0-10v standard) which the hardware takes care of as well.
I really appreciate how you make the effort to show where the wiring is coming from, going to and the route it takes. It gives a feeling of continuity (pun intended) to the circuit and why things are made the way they are made 👌
I’ve lost my house, family and friends right before Covid and WWIII began. To mentally survive, I retreated into UA-cam, mostly educational or artistic content-like this. Just wanted to “interact” and show my appreciation for creators like you, thanks.✌️
One of my favorite "contactor stories" was a discovery made in our computer center during a every-other-year power shutdown and maintenance weekend effort. A big UPS system was in the data center with a massive string of 2.25V lead-calcium storage cells in series for (I think) 432VDC @ 400 amps as input to the UPS system. A giant contactor was used for the EPO (Emergency Power Shutoff) for the entire computer room... red shutdown buttons on the computer room walls were in many locations to push should a major electrical issue occur. With all computers OFF, the big EPO contactor was being tested, and it ended up failing... it shut the power off fine, but it would not re-energize and close the contacts for the main computer room. Any place to get parts was closed. After a "hilljack engineering discussion", the contactor contacts were forced CLOSED with a piece of wood. All computer room staff were made aware of this naughty bypass, and where the manual power panel disconnect was located should a real emergency occur. Things ran this way for a few weeks until a new contactor could be ordered and installed; they somehow did it on the weekend and were able to isolate/bypass the contactor to replace it without another computer room shutdown.
At Cheswick power station we got a frantic call from the barge unloader that the barge mover wouldn't shut down. We killed it with the disconnect, then found that the contacts on the contactor were welded together.
I am once again astounded by this channel's ability to make a video on such a topic interesting, enjoyable, humorous and worth watching the entire way through.
I worked at a electrical supply warehouse for three years and it was a maze of parts and cryptic part numbers without much of an idea what all of it did, outside of the abstract. I do often read articles to satiate my curiosity, but I didn't like working there, so it never passed the threshold of curiosity needed to find the articles. It's funny that years later I'm now learning what all those things I sorted and packed and catalogued actually do, thanks to you Technologically Connecting me back to the subject.
As a train guy, I appreciate the mention of just how absurd the early DC traction systems of locomotives are. You have a real knack for making this stuff interesting, and informative!
@Technology Connections, hopefully you read this. Want to tell you that this channel and content has always been absurdly interesting and that it is because of you I learned more about engineering than I ever thought I would. Please keep making videos, I happily await each one to brighten our day!
I've worked in industrial automation for about 10 years now, but my first job had me work near 4160 Vac cabinets... those contactors and fuses were ridiculous and gave me all the scares. Luckily now the worst I've got to deal with is 120 vac after swapping jobs. Long story short, I really appreciate this channel and have recommended some of the videos to my colleagues who are about as nerdy as me and the new guys because of how well he explains how certain tech works. Keep up the brilliant work!
Years ago I worked in a lab where one of the machines had a switchboard cabinet with a 63A contactor in it. One day we had a specialist in who managed to trip that one. Me and my colleagues present jumped quite a bit but the specialist just shrugged it off.
@@TomFynn People can get used to a lot. There was an electrician that I worked with that was a little more adventurous in some of the higher kcal cabinets, so I can easily see a specialist go "eh it's just another Tuesday"
I actively work in the field, and most of the things mentioned in the video sounded like bread and butter to me, and I've only just realized how little contactors or frequency converters appear in most peoples'' lives. Things like these make up the bulk of many switching cabinets in pretty much any production plant anywhere. These clicky dudes are what make the things go, that produce a lot of the things we take for granted as consumers today.
The part of this video I enjoyed the most was the closed captioning @7:00 transcribing the sound of the AC unit starting as "[BRRGSHSSWMMMMAHHHH]". :) Excellent work.
I’ve been an electrician for about 35 years, and have done industrial, commercial and residential electrical work. I can’t begin to tell you how many contactors I’ve wired. These days, most things are being controlled over “Smart Systems” so that we can control them over WiFi or Bluetooth and they still use contacts! But your explanation to this audience I found entertaining….😊
Note: a big advantage of solid state/semiconductor relays is that they can switch an AC voltage at its zero point. That is, it can watch the line voltage reach zero in the cycle, and switch at the zero point, effectively breaking the circuit when there is no current whatsoever flowing.
@@scottfranco1962 With a resistor the current and voltage are in phase, but reactive loads will cause a phase shift between current a voltage. The current zero crossing and voltage zero crossing will no longer coincide.
Neither a mechanical contactor nor this type of solid state switch will work with DC because - obviously - the voltage never goes to zero (of course there's also no phase so current never goes to zero either). HVDC switches have to be much more sophisticated and expensive than HVAC ones. Along with no transformers this was the killer problem in Edison's DC system.
Those lighting contactors make a really nice 'thump', when they pull in! For high current loads, the old mercury contactors were very reliable. Obviously, mercury presents a few issues, but it did reduce wear. Also, a VFD video would be awesome.
It's really sad that the room temperature liquid metal is dangerous precisely because it's liquid at low temperatures and fumes a lot. But if it's covered it's safe from what I recall, so I guess it's probably still used in some electrical applications. I just searched and it is used in tilt sensors, sensibly.
@@KarolOfGutovo Yeah, I decided to extract some mercury from a large, three phase, contactor once and it was not easy. They're pretty solidly (haha) built.
@@KarolOfGutovo Honestly the only really fuss I remember with them was old fluorescent tubes used mercury vapor, so obviously dangerous in the case of breakage, and common consumer appliances that were ending up in landfills. I think plenty of specialty electronic components still use mercury alloys and liquid in small quantities, it's just far enough away and hidden from the consumer space that no bleeding-hearts have caused a ruckus about it yet.
One problem with these contactors in HVAC equipment is that bugs or other creatures can crawl in between the contacts and prevent proper functioning. I think the older ones used to be more open, but newer designs have put more plastic around the contacts.
I recall that the origin of the term "buggy program" or "a bug in the software" traces back to the 1940s electro-mechanical computers, where an actual insect was found jamming a relay! My first job in the Navy (many moons past) was as a Analog computer tech controlling the gun systems on Destroyers, and spent many hours cleaning and re-lubeing the related mechanisms; a chitinous critter in the wrong place could definately ruin my day! Fortunately, plagues of beetles are rare at sea - more an Army problem😅; Though now I recall, we did have a migrateing swarm of bees try to setup shop on our bridge deck when we in the shipyards of Singapore, caused some exitement fer sure😮.
I too was quite surprised at seeing how open everything is in the HVAC unit. That being said it appeared so clean (free of dust) I can only assume it must be completely sealed from the outside
@@KevinSmith-ys3mh that's a bit of an urban legend; the term "bug" for glitch already existed, which is what made that story from the 1940s notable when it occurred :)
I had to stop this video one-third of the way through to leave this comment of praise and admiration! I've watched SO many unhelpful electrical videos in recent days that either assume too much or too little of the viewer, and this one hits everything on the head. Definitely a new subscriber, thank you so much for the excellent video and looking forward to many more!
My sister and I drove from SF to Vegas a few weeks ago. It wasn't until the fifth or sixth charge that I realized how much juice was being moved. She was chatting with another Mach-E owner about how some relays fused together. It was then that I realized how many angry pixies were moving and how they were even angrier because of speed. The engineers behind EVs have a hard problem to solve, and I appreciate how far they've come, so far. When she charged my apartment's monthly power usage in 25 minutes... yeah those pixies are angry, and I was impressed.
I remember my work as electrical technician some time ago. Our mechanics had elevator from factory to warehouse, and they once did something funny and came to me asking for help. Elevator motor had two contactors, one for going up, one for down. Both had its coils connected via special NC contacts of other one, just to be sure no one tries press both buttons, up and down simultaneously, causing a short. So, elevator is on the first floor, refusing to go up. When up button is pressed, there's an audible humming and a bit of strange smell. I open the contactor box - everything looks just fine, both contactors intact, properly connected. I take my poking device, and poke the up contactor. Elevator goes up, no problem. I ask guys to press up button, and contactor is going crazy - loud humming, lots of sparks, elevator goes nowhere. I inspect contactor closer, and its coil is rated for 380VAC. I look at its neighbour - its coil is 240VAC. So the correct voltage was 240, and 380 coil wasn't strong enough to firmly pull in the links, so it was closing and opening 50 times a second instead, drawing LRA of the elevator motor, creating nice arcs and a bit of smoke.
I work at an older visitor center at Mt St Helens. In the basement is a Snow Melt System. I ask about it and get told “it doesn’t work, never has”. Talked with an electrician the other day and we troubleshot it, and found the contacter is bad. It’s a big one. I’ve been doing some googling about how to repair it, and even though I’ve been a subscriber to your channel for years now, this video popped up in my feed. So, thank you algorithm!
Common in smaller units, it is around a third of the price cheaper, though I change them to double pole ones when replacing them, even though I live in a country with 230VAC mains, as the double pole unit as a spare part means you only need to keep one to cover both use cases, and then a second 3 phase unit for bigger units that run on 3 phase, where you have a 4 pole unit typically, with 1 pole also used to power the single phase cooling fan separately. Double pole means less issues with tripping when the wiring outside gets wet, as you typically will have the unit hard wired, and thus simply turning it off will allow you to fault find and isolate the unit. Plus compressors often fail as a short to ground, with split phase the unit might keep on running at part power, till the motor itself burns out the wiring.
Just be careful if you are doing a heat pump, because typically one side has to be wired through. If you do double pole, then you'll have to make sure, if applicable, that a heater for the compressor still works afterwards by wiring properly.
@@sprockkets Only ever had one unit that actually came with a heater for the compressor, and that was because it was run really hard, with inlet suction at 0C, for a split AC. It killed compressors, and eventually just charged it to around 5C at suction, and it ran a lot better. After all discharge temperature was around 70C on the high side, dropping to 40C when the hot liquid left it, so it was definitely running flat out. Put a large liquid line drier on it to give more liquid volume and a little more restriction as well, fixed cap tubes and not wanting to do the manufacturers designing for them. Left the heater off then, it was a lot happier, just pulling a nice puddle of water from the air instead of the ice block.
Good job of explaining contactors! One minor thing I would add is that they are useful for even low loads when the switch is far away from the line that feeds the load. Having a contactor helps to reduce voltage drop by shortening the wire length needed from line to load. I use this approach to power my pool lights, for example.
@@sphygo (of course I was making a gaggityjoke, I knew what he meant, though it took me a second. i'm kind of surprised uninterruptable power supplies have their own technicians)
@@KairuHakubi Probably because you're thinking a the wrong end of the UPS scale. The kind of cheap, simple, often offline, UPS systems you'll buy for your PC are rarely repaired (like most consumer electronics). Larger, more complex UPS systems are quite complex, quite expensive, and there are certainly a lot of techs that specialize just in that. Think the kind that are used in, for example, datacenters. They cost absolute fortunes, and can be absolutely massive.
I was absolutely stunned how easy you could pry that Eaton contactor! Here in Europe, opening such a thing up is hardly possible and usually requires destruction. At least, the types I've opened up where not at all made to be serviced and had to be destroyed up to a point you would not be able to use them anymore.
Last week, I was instructed in the course to automation technician to disassemble a contactor and find out the order number for a spare coil in case it got burnt, and then the number for a coil of a different control voltage. Never having taken one of them apart before (but aware that the difference between opening those plastic tabs and breaking them off is really small), I carefully went to work, separating each and every component in the entire contactor while finding out exactly what parts kept each other in place. Having located and freed the coil, I tried to look up the numbers stamped on it, but google wasn't my friend, so I took the whole pile to the teacher to ask where the heck I could find the requested information. Turned out that, just like you said, the A-series of ABB contactors aren't meant to be serviced lmao Teacher asked where I found it (that box of them we use for motor installations) and only then get informed that they have some old ones just for the exercise I was doing I once again got told to stop destroying school property as the contactor I had taken apart couldn't be reassembled. Wise from my previous experience when I had to disassemble some additional circuit breakers (hence the "again" part) to figure out exactly how all pieces fit together, I just grabbed another contactor from the same box and got to work. If I do it again, it probably go a lot faster as I'm now familiar with the construction, but to sum it up, contactors that are meant to be replaced CAN be taken apart to be serviced, but it's not worth the extra time and hassle.
@@johanmetreus1268 Ofcourse contactors with contacts that are meant to be replaced can be serviced. But the contactor he shows in the video would certainly not be one you would find serviceable here in The Netherlands/possibly whole of Europe, but in general we also don't have the contacts to the coil at the sides of these things, but always below or above the power-contacts. Whether it's worth the extra time and hassle depends largely on the type of contactor, the availability of parts and downtime that is deemed acceptable: if you don't have spare parts but it's absolutely necessary to get the system the contactor is in running again, a good cleaning of the contacts good bridge the time till you do get the spares in. Usually the bigger the contactor, the more worthwile it is to service it. Advice for everyone: if you want to find out if a contactor or other electrical part is serviceable or not: look up the type/modelmarking on the unit first. You'll usually end up at the manufacturers' website, where the absence or availability of spares will tell you something ;)
As someone who works with industrial equipment it is indeed very satisfying to be able to just press a small button and hear a nice clunk as the equipment powers on (in our case the contactors are powered by 24V, which is under control of the safety system, if the safety PLC detects an error you won't get high power)
On industrial contactors you can often attach a kind of switch to the moving part that can give signal back to the PLC telling if the contactor is actually engaged, or if it is engaged when it shouldn't be. Some contactors also need a helping relay because they draw too much power from PLCs og control boards.
@Ithecastic I dunno. 'chill' by no means has to mean lax and, and I find teachers who actually try to make learning fun and engaging to be much more effective than teachers who are uptight and serious all the time. Sounds like you may be projecting just a bit due to some bad experiences with lazy teachers in the past. Unsolicited armchair phycology sure is fun, isn't it?
I’ve never heard so much discussion about which color wire does what since the last time I saw a movie about bomb disposal. Now that I think of it that would make a great episode on this channel.
I work for a major industrial refrigeration company in the US (you’ve seen our stuff if you’ve been to Walmart, Kroger/Fred Meyer, Target, etc.). We are starting to use more VFD’s on our refrigeration rack systems to control compressor motor speed keeping energy efficiency up. Really cool (no pun intended lol) to see you mention this stuff! We are also beginning to introduce CO2 refrigerant into a new product line of ours because it is more energy efficient and better for the environment compared to R440A or R448A. Love to see these changes taking place!
Fantastic video! I work with lighting controls, and contactors are something we design with every day (using our system to add a "brain" to them), and there are often large panels full of multiple contactors we interface with. Some of our newer team members have had trouble with the concept, so I'm definitely going to be sharing this one with my team!
The star/delta configuration described at 15:59 reminds me of series/parallel controllers found in old trams and electric trains! To start from a stop to low speed the motors are wired in series so they split the voltage between them, preventing the motor coils from burning out, then when getting up to speed the controller switches so the motors are in parallel and get the full voltage each to safely run at higher speeds. EDIT: you briefly mentioned DC train control after I wrote this comment :)
The older NYC subway cars have a 3 position controller - switching, series, and parallel - I never did learn what the switching position did, but have read that if you left it in that position for too long, you could burn out the train's giant resistor grids
I just love this channel so much. I love learning about stuff that I would never even ask myself how it works. I love your writing and your jokes and the way you deliver them. Just great. Thank you!
I love how you explain things so simply and with plain language. It's very accessible without being condescending. Very well written. Great job! Keep up the good work. I learn a lot on your channel.
I can still recall the exact day my lifelong fascination with science and technology and engineering started. As a kid, I happened upon an age-appropriate book on how home electrical wiring worked. Fuses, insulators, transformers, circuits, power generation and transmission, etc. Prior to that, like most kids (and probably like many adults even now) the world had just been unexamined, and kind of written off as working by magic or whatever. While reading that book however, a metaphorical lightbulb went on (ironic), and I suddenly realized that things made *sense* if you took a moment to look into them, there was a logic and structure to the world, and people could and did apply clever planning to put together elegant working systems. I've spent my life ever since seeking out knowledge and learning how to make things work. The style and content of most of your videos bring back for me that youthful sense of "aha!" and fascinated wonder, thank you.
I'm so glad you're putting up these videos. I'm a control systems engineer who works with this stuff a lot, but I've never known the inner workings. I knew a fair amount (since this is my field) but you still managed to teach this old dog some new tricks. Thank you many times over.
Very timely! I just had my HVAC go non-functional because of ants getting up into the contactor and preventing the circuit closing. Now I have a name for the device that the HVAC guys wanted to charge me $300 to replace, even though a bit of canned/compressed air is "good enough" to clear it. Thanks! ❤
The contacts are most likely burnt up from making a poor connection with high resistance. You may want to just replace it, unless you can go without AC while you get another.
To keep the ants out you just shake borax all over the base of the AC outdoor unit, and on the base of the electrical connections. Redo every year, and you will never have ants again. Same for electric gate motors, I keep a bag with borax, another with blue death and a can of spray for the quick removal.
To be fair to hvac guys, there's a minimum cost to make the trip, and to verify that it's just the contactor & not something else. Feels like crazy markup till ya think of the cost to roll the truck. Such is life for all service work.
Thank you for finally explaining what the actual difference is between a contactor and a relay. It's something I've asked people several times before, and never been able to get a straight answer.
I work as an industrial electrician, lots of times working with huge contactors from the 60s-70s. Super cool to see you do something like this man, great video!
For the hotel example, if the items and their breakers are spread all over the building then it will mostly have several different contactors (usually one per breaker) and all the contactors are operated as one from a central control circuit. You could run hundreds of contactors from one control circuit spread across many different breakers in many different locations.
Yep, I'm pretty sure it's not kosher to run stuff on different breakers in the same multi-pole contactor. Never bothered to look it up, wouldn't have a reason. I can see that multi-pole monstrosity being used for stadium light poles though.
In that case, it's actually done throigh relays. A breaker will typically be 20A, with voltage ranging from 120-347V for single pole applications. Most lighting (apart from highmasts and some warehouse lighting) are all single pole fed. So contactors aren't actually required, or used. It's all relays controlling zones of lighting all fed from a central LCU (lighting control unit)
I worked in a large retail building and it was fun being there in the morning. Different areas of the stores lights would turn on over the warmup period. My boss had a breaker box in his office and you would hear a lot of the breakers or contractors kick on every morning. I know that they had some kind of central control but I never bothered the electrician on staff.
@@c31979839 For most of the commercial lighting control work I do, I use relays with 25A rated contacts usually fed from a 15 or 20A circuit. Our company got away from using contactors since most people are irritated by the clunk and hum they make.
Took s few coklege classes in this for my ME degree, and after having worked in a shop setting with alot of heavy equipment and regularly changing out broken contactors, wye delta starters, and programming VFDs, i can say i really appreciate this video
I was hoping for the day you can fully explain contactors. Its something i was fascinated when learnt from them on school and its nice to show appreciation for one of the keys of analog automation for electric systems
Great timing! I'm making a UPS system for my friend that swaps between normal and backup power without the UPS needing to provide full power, especially in normal operation. It removes a few advantages of the UPS like power filtering, but it can be mitigated with external solutions for a fraction of the cost of a larger inverter. His house grid is a three phase system, but I've decided to only power two of them in the case of an outage by splitting the output of the single phase UPS as there are no multiple-phase appliances in his appartment to suffer from that and one of the phases powers only things (clothes dryers, washing machines etc.) that aren't really prefferable to feed from valuable battery storage. Contactors are pretty much the best way to do that and I love them.
For those curious to know other uses for contactors. I decided that I wanted better control over a pool setup that was run by a simple Intermatic pool cabinet w/ a mechanical timer. Most pros will say install a pool controller unit, but the grift is that most are over a grand. So, wanting to integrate some automation into my setup, I gutted the mechanical crap, installed a 30A DPST 120Vac coil contactor and used a z-wave Aeotec ZWA038-A as the coil switch and presto; one schedulable pool pump w/ power fail last state and manual over-ride. Replaced the lamp w/ 50w LED and a dusk-to-dawn relay and all told, paid 1/10th the cost of a panel overhaul. Only catch... as the pool is in AZ, I needed a switch that's tolerant of higher than normal temps and the Aeotec was the only one rated to 50C, whereas most only go up to 40C. Since this is also an automated setup, there are other "safety" protocols that have been put in place, such as overheat and freeze protection. As an aside to this, I recently rigged an over-pressure switch/contactor (you find these on water wells and hot water circulators) w/ a z-wave contact sensor to protect against filter blowouts. I may have a simple pool setup, but you can imagine the possibilities for those that are not so simple.
In a warehouse I used to work at, the automation kept having contactees fail. I remember the answer I got when I asked what one was. "It makes contact" was all I ever got, so helpful video.
For some weird reason I absolutely love the sound of automated relay/contactor clicks. There's a detailed video of KITT's scanner (Knight Rider) out there where they put the camera up to the control box, and if you know how fast KITT's scanner scans, you can just imagine the sound of the relays going.
Me too. By coincidence I made a video today of a level crossing at a trainstation nearby where the relay-cabinets are accessible to the general public (read: not open or anything, but usually they are besides the tracks, surrounded by fences, making it impossible to come even close, this one is right beside the platform-walkway). I walked by one once and was surprised how well I could hear the relays going. So today I made a special recording of it. It was so nice to first hear the significantly bulky 'clunk' when the announcement-section drops and activates the crossing, which in turn starts a whole concert of click-clacks at different speeds as - in contrast to most other crossings on this planet - Dutch level crossings usually consist of multiple pulsators (? see below) that are (I never liked it) not in sync. From what I've read this is a redundancy thing, so a pulsator that breaks down, does not completely disables the flashing nature of the red lights at a crossing. ? pulsator? No idea what they are called in English, but they deliver the pulses to make the lights flash in an alternating fashion. Either we called them EOR45 and EOR90 (Probably standing for Electronic Oscillating Relay, with the numbers stating the amount of pulses per minute or this abbreviation was derived from GRS, the company where we got most of our railway-signalling electronics from in The Netherlands. Just like the elevator at the company where my dad worked. As it would go up you would hear a 'click... click-click... click........ sequence as it passed another floor. I also made a three-way junction with lights at school as I was learning to become an electrician. I had to get extra cables from the measuring-department and it used up all available switches and relays from the practice-board, but it worked. The only thing it didn't do was provide a crowbar-situation should a relay get stuck and than provide a conflict-situation (green from two conflicting directions). In the past, this would cause a short, rendering the junction to fall back to flashing amber. It's all electronic now.
those would have just been relays, but yes I can imagine the waterfall of sounds as it "scanned". I've got a 8 pole attenuator here that can cut in 0.25 through 32 db of attenuation on 8 relays, but it must be switched with binary. made an arduino sketch to tie it to a simple pot, and you can imagine the sound it makes if you quickly spin the dial. (256 states)
Sorry to be that guy, but those wouldn't be relays but transistors, those weren't new in the 80s, and before vacuum tubes would be used for fast applications. Relays would be used only for the final switch of the electric actuators that control the car because they're not really fast
Love that you went in to Delta-Wye. Next step above Delta-Wye before you get to full on VFDs is SCR based soft starts which could make for an interesting video because it is similar to how old school dimmer switches worked and you are more in the household cool things vs industrial cool things. Then you could also get in to zero crossing and random crossing AC SSRs... or maybe that's too out there. Also SSRs are actually stupid cheap these days. Thoughts from an industrial EE.
My friend had her air conditioner go out yesterday. I figured I could at least check the capacitor, but that checked out (shocking, since it's over 25 years old and we get huge temperature swings). Then I saw the contractor and recognized it as that thing in the TC video from a year ago. It actually sparked when I turned on power. Looked a little closer and realized the part I thought was a weird (maybe fried) connection bit was actually a weird (definitely fried) bug that made a home under the moving bit. Moved his corpse out of the way and the thing fired right up! Thanks for teaching me about contractors so I would bother to look at one. Saved my teacher friend a lot of money when she was afraid she'd need to replace the unit
I'm glad you made a mention of contactors for rail equipment here, high current DC comtactors (particularly those used to control energising catenary wirres) are huge and demand respect.
Fun Fact about computers: - In the old AT design, the Power Button directly switched the main voltage wires of the power supply. - But in the ATX design, the power Button switches a relay on the motherboard, that in turn switches a connector in the PSU. One advantage is that the computer can turn itself off after shutdown (AT ones could not do that). And once you add a bit of Standby Power, we can have features like "wake on keyboard", and even "wake on LAN".
Actually, ATX power switching is a bit different, and I have never seen a power relay on a motherboard. Upon registering a power button press, the motherboard will pull down the PS_ON# signal in the ATX power connector, an active-low TTL-level affair. This turns on the power supply. (Standby power thus is an integrated part of the whole operation. There is usually some debouncing and logic between the switch input and PS_ON# output, I think this is mostly handled by the Super-I/O these days. I imagine it would have been little more than some basic debouncing back in 1997 though. And if you just want to turn on the supply manually, you might use a paperclip or similar.) Once output voltages are within tolerance, the power supply pulls up the PWR_OK or "power good" pin to tell the board that power-up can commence. (If you've ever encountered a dead PC with "lights on but nobody's home" syndrome, that's generally an unhappy power supply.) Upon a regular shutdown / suspend to RAM event, if "power good" ever goes down or during emergency shutdown being triggered by overheating, the board will let go of PS_ON#. For all the gory details, you can look up the _ATX12V Power Supply Design Guide._ The latest version is called _ATX Version 3.0 Multi Rail Desktop Platform Power Supply, Design Guide,_ though I don't think there have been any changes to these signals in absolutely forever (except nowadays the supplies are required to handle a lot more power cycles as Modern Standby = S0ix may involve periodic waking).
As a British Electrician/Plumber/Massive Nerd, I do find the videos where you give description of your heating systems quite fascinating. Your ducted gas furnace systems with in-line aircon evaporators, are essentially a scaled down version of the AHUs we use for commercial premises.
Now try asking why the difference exists. I'm not sure, but I suspect it's to do with house size: Air ducting takes up a lot more room than water pipes to move the same amount of heat.
@@vylbird8014 WAY more older house in Europe, and it's a whole lot easier to retrofit water lines vs. air ducts. Hence more mini-splits & boilers than we see in the US, especially in the Midwest where both heating & cooling are pretty much universal.
Hot water and steam systems used to be extremely popular here (hot water still is in certain areas, eg New England), but fell out of popularity in most new construction in favor of forced hot air in the late 20th century, mainly due to it being more cost effective to have air conditioning and heating share the same system
At the fire department there’s this really old siren there and it’s also controlled by one of these contactors and to activate the contactor, there’s a simple light switch and that sounds the siren. However, sometimes the contactor gets stuck so we have to cut the power to it move it a little bit to get it unstuck, and plug it back in and flip the switch to get it sounding. Now we only sound the siren on special occasion like the Fourth of July so it’s not exactly maintained but we keep it unplugged whenever it’s not being used so it’s fine. And besides, the siren doesn’t sound sick or anything it sounds perfectly healthy and fine as if it were brand new.
This reminds me of the time I had to do a deep dive into contact materials for these things. They often use contact rivets of silver tin-oxide or similar mixes of silver and some oxide to prevent premature failure. Especially contact welding is something you want to prevent at all costs. The standard material choice used to be silver cadmium-oxide, but since heavy metals are not so nice to have everywhere researches had to spend decades to develop alternative formulations that could compete with the poisonous variant. Quite similar to the whole lead-free solder thing.
What I saw on a gondola lift recently was that there was a secondary smaller electric motor, to spin up the main motor in order to overcome the locked rotor
Our warehouse has a fun old setup of relays and contactors. One switch will start a cascade of contactors all initiating after each other (to not overload the main fuse) with fans and lights. That lovely "Click - Hum - Click - Hum - Click - Hum" rhythm makes me always smile.
I love learning from you. It’s the perfect blend of info, dry humor, and interesting tangents at the right knowledge level for me to truly absorb. I’ll have to listen for the clacks in more places now that I know, but I have to admit the wildest one was the kachunk a Tesla makes as you put it into a drive mode. I actually had to ask what the hell it was because it was pretty surprising and I wasn’t expecting mechanical sounds from an electric drivetrain. I’ve also had to deal with the unfortunate situation of having no AC at my house, and I went out of my way to buy “inverter” window ac units so they spin up gradually and somewhat quietly compared to the clunk of a regular unit. Im glad this type of variable power control is filtering down into mainstream appliances as it’s so much nicer and as you mentioned, more efficient than the old kind.
This 01 Electrician approves of this content! Just did a little under 3 years working on conveyor systems with most of what you mentioned. VFD (variable frequency drive) are pretty standard now. You can save power and extend the lifetime of the motor. On the operational side, the control systems can do amazing things with VFDs. They can control and monitor the belt speed to such a degree that orchestrating dozens of baggage lines as they merge, split, and stop/hold baggage for security reasons is a matter of programming via laptop in a tiny room between the bathrooms in the bagwell. Thanks for the content! PS: overload protection is the primary distinction between a contactor and moter starter
As someone getting more and more into industrial automation, this was a treat. I've always loved your videos but this one I can relate to closely. Would you consider doing a video on PLC components sometime? That'd be cool. I know there are _tons_ of different ones, but maybe something like the basics of a PLC, or PLC fanless computers vs a standard computer. There is soooooo much to learn about it and I'm excited to really get into it.
Get a true understanding of electromechanical control systems, building logic circuits with relays. Start program the PLC in Ladder (one of the five standardized languages) and you quickly notice how a latching circuit equals a bit of memory, Switching to Fb (Function blocks, another standard PLC language), and you'll discover how OR equals contacts in parallel, while AND is contacts in series. Once you have those two down, you can then use lL or STL to speed things up as you can just type shorthand commands instead of dragging the graphical symbols around.
I use these when assembling control units for actuators.this is going to be fun to learn exactly how they work! Same brand as well! Although the ones we use are longer
I smiled when you pushed that in to manually override. We've done fun stuff like this... except, moving elevators up and down without the logic being aware in the slightest. (more older models however) :D
That sounds like a hilarious prank to pull on your unsuspecting coworker. Newer models of elevators should hopefully have some feedback sensors that will alert the controller to a non-standard movement event.
@@EmptyZoo393 Definitely! Their all more or less operating systems at this point. Not what they used to be (just a few relays and contractor wired in intellegent ways made a lift logic in the day..) So definitely if something moves out of the ordinary it might just go crazy, but hah, it's one of those things where different logics might react differently and that too would actually be quite interesting to see :P
In college I worked at a large entertainment & sports arena. My role meant I had master keys, so I took it upon myself to explore and learn all of the building's systems. The lighting control was interesting for its day... It was controlled via a Windows app connected to relay cabinets attached to the bottom of each of the lighting panels throughout the building. There were a few easy presets to turn on the exterior lights and each type of indoor light and the facilities team could make individual adjustments if needed. Years later, I worked for a large museum which converted to a similar system that added a relay cabinet next to the existing lighting breaker panels. It was also networked, but we had the option of hitting a button on the relay cabinet circuit board to make manual changes. I'm sure that building's owner had more capabilities than we used, but they had too many other problems to worry about customizing our lights. :) One thing I did learn was commercial building lighting often uses 208v to save copper on long runs of lights. This is why manual light switches in those buildings are usually a bit stiffer with a more defined click; they have to be rated for 'high voltage.'
I've installed hundreds of not thousands of contactors in residential, commercial, and industrial applications. They're fascinating, a brilliant application of engineering. The clunk you hear on your ac compressor right before it starts, or, in a empty stadium, clunk, a group of lights come on, that's the electromagnet activating and releasing or pulling the contacts.
Hey Alec, can you make a video about how an electric train/metro/tramway is powered? And how the tens of thousands of volts get supplied over the long rail route?
Hello! One thing I didn't touch on here was the power draw of the contactor itself. For the contactors I'm showing here it's quite small (just a few watts) but there are some applications where a latching contactor may be desired. These have two magnets - one to close the contactor, and another to release it. These can save some energy, but come with the risk that a control system failure may leave the contactor engaged. Depending on the application, that could be _very bad_ so they're far less common.
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Thank you for this. Could you do a full breakdown of an HVAC system? You know your stuff and I trust you could explain it better than anyone else.
Also the theory of dark matter and how it could be the next step in the HVAC evolution.
it is so tiny, compared to the 200-1000 amp 480 volt ones I work on on EOT cranes. They have arc flash and arc fling units
You could have a collapsible circuit on the disconnecting coil, so if power is lost a capacitor discharges through the disconnect coil, adding a fail-safe mode.
Finally, a video on this channel is actually about technology making (or breaking) connections.
He has made videos about switches
oMfG hOw diD yOu cOmMeNt yEsTeRdAy iF tHe vIdEo WaS uPlOaDeD tOdAy??!????????
It required seven years of practice before handling the really big connections.
I would boo you but at least it's better than the 'seasonings greetings' joke
god damn it you beat me to it
I just want to say as an hvac technician your channel has been invaluable for showing less tech minded coworkers breakdowns for things we touch everyday. Your refrigeration episodes genuinely get pulled up very often
Don't y'all sign contracts in crayon? Hvac tarts
@@GoGoErrek how dare you sir, only the finest Crayola for my customers!
@@eliwoodthegoothoonter538 truly, men of culture!
Hvac? Well a ragulair electrician wont bounce back from a normal relay, what niveau did you study even at Hvac?
@@ClosestNearUtopia I'm not 100% what you're trying to ask but you're asking what I have studied, I have a degree in industrial electrical, including PLC, analog controls, solar, and instrumentation
5:20 fun fact, this is also a major reason why restoring power after a blackout is trickier than you'd think. If you restore too much coverage at once, everything that's plugged in will restart and momentarily draw startup current at the same time, which runs the serious risk of blacking the grid right back out again.
Huh neat, makes sense though, I’d just never considered that
you explained the function of a light switch so elegantly
I like gay men.
Yo what
Thanks UA-cam, very cool
wow it's THE UA-cam
Some employee forgot to switch to their personal account I bet
"I said we wouldn’t get lost in HVAC trivia."
The whole video is trivia and we're here for it. Embrace it. Distribute it.
Short version: Electromagnets control a physical conductive switch. The end.
HVAC Trivia Version: hey did you know that connecting these two 24v wires on my thermostat triggers the AC to go on?
@@randomblock1_ Correction, rewatch the video- thats 24vac from the supply transformer in the airhandler unit. And in a modern smart thermostat the 24vac is rectified to either 3.3vdc or 5vdc logic power to run the control board.
The little click sounds you hear from that thermostat are from the micro-relays that switch that 24vac as signals to control the airhandler blower and outside compressor units. Much going on under the hood, to most users its just magic stuff that works, ideally.😊
@@KevinSmith-ys3mh Very nice explanation. 😎
@@KevinSmith-ys3mh Some low end electronic thermostats still use AAA batteries, that need to be periodically changed, but that's still worth it for the energy savings.
@@buddyclem7328 yeah, I hate those things, they are a servicing call waiting to happen when the next owner moves in, the manual is in a junk box or trashcan, and the batteries are leaking and corrosion all over. They should at least use 10 year life lithium packs like new smoke detectors, and have legible labels on it to inform the users. They are mostly a replacement for the older round mercury switch dumb thermostats and to avoid pulling newer 6-8 wire cabling. With any luck in the next generation systems they will move to fully digital wireless connectivity & controls and wiring problems will disappear! 🙏🤗
Better control systems are possible for a reasonable price now, saw one on the "this old house" tv series recently that a typical DIY guy could buy as a kit and install! The problem with change isn't hardware, it's the hidebound mindsets of companies and installers. 🙄
As an HVAC tech I would happily show this video in a classroom setting to people who are learning about HVAC. Everything you said was correct!
yup, covered the wiring better than my instructors did at school. Just a 2 day module cause we were going into factory maintenance. Still better than what I paid for.
@@Raeilgunne Having not gone to school for HVAC but being in the field, I would definitely show this video and his previous videos on heat pumps etc to new techs. Installers, maintenance and service techs can all learn a great deal from these videos
the fact that the main focus of this video wasn't even hvac systems lmao
Having worked in Industrial Controls, his lack of PPE would caution me from showing the footage in a learning environment (when taking voltage measurements at the HVAC unit), as it would set a unwanted precedence. Safety First, even if it is just 120VAC. The lack of proper PPE when working on live voltages over 50 Volts would have resulted in his immediate termination at any of my former employers.
@@vernendalencientariactal What kind of PPE would be suitable?
One common criticism in movies is that stadium lights don't actually make that "chunk" sound when they come on. But a warehouse I used to manage used contractors to control the lights, and they made the most satisfying "chunk" sound when activated.
Two stadiums where I have switched lights do make that clunk, but it is in the utility room usually far away from the switch being flipped. They use contactors. One of the stadiums used several contactors with a little box that sequentially turned them on about 1/2-1s apart to avoid a huge starting surge.
I guess they do but not where the camera is usually at.
(I guess they do it in the electric room)
Not quite a stadium but I used to work at a tennis court complex occasionally and those big lights definitely clunked
Did the lights come on in sequence, each with their own 'chunk' noise, in order to dramatically reveal the alien spaceship or high-tech fighter jet that was in the warehouse?
Hahaha just image being in a power distribution room and toggling over 20 medium voltage contactors/switch's/connect barrs etc in sequence, you feel your body shiver
As an electrician that works mostly in commercial and industrial jobsites I appreciate the way you can explain something so simply anyone could understand like an apprentice. I will use this as a reference when explaining these to those apprentices who just don't seem to get what I'm saying
@@epistemophiliac5334 I still like watching this channel even though I know all this stuff… If you want a simple explanation for more complex electrical, go watch a guy named Dave Gordon… While I understand electrical systems as I started as a computer engineering major before switching to computer science, I cannot explain things anywhere close to Gordon… Particularly useful if you work with three phase in industrial applications…
I worked for a low voltage company at one point and had access to the elevator room in an old skyscraper. It was literally an entire room filled with contactors. Probably hundreds of contactors big and small just click clacking away as people would call and use the elevator. It was a very impressive show and mesmerizing to watch.
Next time bring a comically huge magnet
Ah man. I’ve been in an old building like that and had the same experience. It’s wild.
@@Dong_Harvey spin around the room with a rare earth magnet in each hand for the lulz.
@@Dong_Harveyoh my god you evil genius
I like everything out of this channel because it explains the kind of things that old corporate videos explain without the associated vested interest.
Dude your totally right lol
You have to respect a guy who has a favourite type of contactor.
siemens' lol 😂
So you're not "cut out" for one minute videos-big deal. Your 20-minute videos do a really good job of not only explaining how something works, but why it needs to work that way (or how it could work better.) And you make them interesting to listen to. I spent a decade as a corporate trainer, and I understand that's it's not easy to put all that together
Well there's currently 441k people so far who watched a 24 minute long video on a fancy electric switch, so maybe we're not cut out for watching one minute videos too :P
Unfortunately, while this is totally true, youtube has changed their algorithm because they're afraid of tiktok, and now creators that do not also publish 'shorts' are penalized in the algorithm. So if you care about growing your channel, you too must dance.
I just finished watching a video by Logically Answered about how shorts aren't profitable enough and now platforms are starting to move away from them, so it probably won't matter in a year.
@@pendlera2959 I hope you're right.
@@pendlera2959 Shorts aren't profitable enough so we must all wear long pants. :-)
One thing you mentioned when contrasting the contactors with relays is that they don't have normally closed contacts. In the field of industrial automation, it's actually very common for them to have additional normally closed contacts, either in the form of a 4th pole that's normally closed, or an auxiliary, low-current contact block that gets attached to the contactor. The purpose of these is to allow detection of welded contacts, as if one of the contacts welds closed, the normally closed contact won't close when the coil is de-energized. I have some old leftover ones lying around that I could send for a connextras video if you're interested!
I have a welded motor starter contactor that I keep on my desk as an example just in case someone tries to save money by eliminating monitoring of the aux contacts
Contactors with loads of "auxiliary contacts" that can be either NC or NO are common in old electric locomotives: e.g. the main traction-wire-to-internal-HV-bus contactor has auxiliary contacts that take part in its self-sustaining, and various contactors that connect various arrangements of engines to the bus have auxiliary contacts that allow other contactors to be powered.
Also, single throw relays are not that uncommon. If you don't need the material for the other throw, it's wasted money.
Those Aux contacts are also REALLY common in industrial facilities for switching auxilarly items, such as indication lights, status to a Control system, providing "seal-in" functionality where only a momentary start/stop is required to start/stop the motor, and opening solenoids for cooling water loops, valves, or closing an aditional contactor to run oil pumps, or other auxilarly items.
@@chaos.corner I honestly can't think of a relay I have seen that is single pole in a modern relay. It can even be hard to find one thats just a single output, so many are dual pole dual throw. I think the only place I have seen single pole relays are the automotive world, where they are trying to shrink them down so much to fit in a tiny electronics box.
I spent a summer as a brakeman on a short-line raiiroad. I had a big "aha" moment here when Alec mentioned the "gnarly" contactors on locomotives. Suddenly, the big loud click that happened when the locomotive was put into dynamic braking made all kinda sense. Thanks, Alec!
I am so proud of you for referring to a meter which is set to current mode as a jumper wire. It can be hard to make people understand why current meters must always be connected in series with the load to prevent bad things from happening. Comparing the meter to a jumper wire gives the user a proper mind set as to what they are doing if they connect an ammeter across a source or a load. I think the ready availability of clamp-on meters these days is making life a lot safer for electrical workers and experimenters.
The other day I shorted out a battery I was testing and immediately checked over the meter to see if I had left it in current mode or something. Nope, it was set to voltage and the leads were in the right place. So I set a different meter to continuity mode and probed the leads, and sure enough, they were shorted. I opened the meter up to see if something was broken and discovered that the shunt that bridges the common and amp jacks was totally uninsulated and travelled directly below the volt jack, so a standard banana plug inserted into the volt jack could touch it and short out.
Moral of the story: anything is better than the $5 harbor freight multimeter
@@FowlerAskew Yikes. I mean my Harbor Freight meter is already in a bin since it just didn't work period, but it'll sure stay in that bin now.
@@FowlerAskew i killed one cheap mmeter that way too, later bought one with actual 10Amp fuse
It's also good to note that a volt meter will also work as a jumper if the internal resistance is too small.
My electronics instructor liked to remind us of that fact with the story of a field tech he knew. The guy used his cheapo meter to test some connection and it basically shorted the contacts. That caused a massive door/vent in a hydro dam to move enough to potentially cause serious harm to someone. (there also might have been an explosion(?), can't quite remember) Luckily no one was injured, but that guy certainly lost his job and possibly entire career.
Suffice to say, that spooked me well enough to only buy decent meters. Plus "buy once, cry once" y'know?
@@SplittingEagle1 an unrelated hydro dam story I've heard is where someone connected the generators to the grid while the phases were 180 degrees out of sync (didn't read the display correctly?) and the entire generator was ripped out of it's housing
There's a room where I work that has a normal light switch to turn on about a dozen massive light fixtures with 80 incandescent light bulbs each. When you flip the switch, you can hear the massive *ka-chunk* of the contactor from behind two walls a hundred feet away. I've sat there for more time than I care to admit just flipping it back and forth because it sounds so neat. Thanks for the insight into the mechanism!
The really big ones use timers so they won't all turn on at once, to manage the inrush current. That's why you get some giant buildings that make the clunk-clunk-clunk noise, each clunk turning on another bank of lights.
Same! Not quite as extreme, but I always enjoyed turning on the exhaust hood at a kitchen I worked in. You'd simultaneously hear the contactor, the fan motors lurching on, and the removable louver panels jostling a tiny bit as the fans made a big enough pressure differential to lift them against gravity.
@@vylbird8014 Ah, I guess that also explains the TV and movie trope of the long hallway or ominous warehouse with lights turning on one section at a time.
@@dfiekowsky I can hear the sound effect in my head.
@@dfiekowsky Makes great TV, yes. But many large buildings did that. This was back when incandescents ruled though - they have a really high initial current, just for a fraction of a second, so if you turned them all on at once you'd trip a breaker. With modern LED lighting, not such an issue.
The spiciest contactors are the ones that have been in service long enough to stick closed, or at least stick closed enough to arc. Those are fun!
Also DC high amperage. They have a bad habit of not wanting to let go, and are rated quite differently.
@@danl6634 I've got 2000A DC contactors at work. They are the size of a small coffee table...
@@MPI1000 got spooked by a contactor at work once when it turned on the supply for 9 1,5MW motor drives. Felt like a shockwave in my chest.
@@MPI1000 Yeah DC stuff is spicy! Much harder to quench a DC arc than an AC arc.
@@MPI1000 yep the bigger stuff is way more interesting imo. Deal with it frequently at work with large refrigeration compressors. 300hp motors just use vfds more often than not to better control inrush. But they also have bypass contactors to deal with vfd faults.
As an electrician-in-training, I feel noticed to have people finally understand the joys and pains of working with contactors
50 years from now, it's very likely we'll still be using contactors. (There are advantages over SSRs.)
just call it Schütz, to annoy everybody
@@fitybux4664 I have never even seen an SSR on anything other than low voltage controls, specifically those 24V and under…
I never seen SSR used in high amperage/high voltage system. Also I think it's psychological barrier, to know this is galvanically separated.
I really do enjoy your videos. This one brings back so many memories.
1. Like when the contactor for the vacuum chamber exploded and threw mercury into the local environment (me!) To prevent contact burns some contactors use a simple plunge into a pool of mercury. Oops!
2. I once met a gentleman who used to work at Stanford Linear Accelerator (SLAC). One day he went outside because he heard a strange noise. Someone had forgotten to crank open the contactors in the beam line. There was a 6 ft arc coming from a piece of equipment into the local earth ground. Yes, arcing into the local soil with all the crackling, smoking and such that that infers. After some time the subsatation contactors opened to break the current.
Apparently it was pretty spectacular. After that experience he thought that a career in retail sales of low voltage electronics was a probably safer choice.
3. At one laser manufacturer I worked at the assemblers of the power supply (15 kW) would sometimes wire in the large capacitors backwards. In test of the laser, that capacitor would heat up and there would be a steam explosion that would dent and deform the steel cabinet. Then the transistor pass-bank would arc out, causing the power company pole transformer to explode, and then they would come and lecture us on being more careful. Mostly we just learned where NOT to park - no by THAT pole.
Such Happy memories!
I had an internship at an electric company which mostly builds distribution cabinets for high power applications. They had huge contactors that had a wind up spring that when engaged slammed the contacts together. You could feel the impact in the floor you were standing on.
Actually those are usually classed as circuit breakers. :) Probably ACBs, Air Circuit Breaker. They come in many variations, with for example a manually pumped spring, or motor operated, with electrical on and off coils, or manual mechanical buttons, under volage relase, with or without built-in protection relay, and more.
I test protection relays and the VCBs (vacuum circuit breakers) protected by them. 12kV breakers still make me jump when they trip. I’m currently working on a system with 345kV breakers and you can feel the ground shake across the yard.
Westinghouse used to make a shipboard circuit breaker that had to be wound up to prepare it for tripping.
Full suit & crank till it stops. Then WHAM! Just noise if everything goes right. If not... the suit keeps all your pieces contained at least.
The windup is to make sure that it operates FAST (reduces those Alex caused arcs)
Turning on massively large lighting systems with a more or less simple wall switch actually did make me curious how it could. Now i know!
No it's actually just a simple wall switch they can handle the same amount of electricity as your average American home (somebody's made it for some reason we all know this)
Some of them use DALI or other architectural lighting control systems. Might see a couple of seconds delay if they aren’t programmed well though.
Industrial lighting systems us rotary latching contactors in a central lighting control panel. The wall switch in your office or hallway is a low voltage device - generally under 24VAC - that signals the lighting control panel. These systems are frequently integrated with broader building automation systems controlling HVAC systems. Modern systems often use digital signals to perform the signaling function.
So, just as a counter example. I used to work for a huge arcade (I think one of the largest in the US actually). All those games are shut off every night to preserve power. One of my many jobs there was to go to the bank of circuit breaker panels (not just breakers, I think there were 6 separate full height panels full of breakers) and manually flip off all the breakers one by one (actually 2 by 2 in the morning once you got good at it) to shut the whole thing off. And if I worked morning shift, same thing in reverse about an hour before opening. No contactor, just on the order of 100+ switches that had to be flipped.
That said, I also got to work with the mother of all contactors, the one that controlled the whole building. I honestly don't actually know if it was a contactor or a giant breaker, but there were a couple scenarios when I had to literally shut off the building and got to flip the tiny switch next to the massive switch in the main electric room. That thing was the size of a basketball and god was it loud when you turned it on as the two giant arms of copper slammed down.
@@JohnR31415 there is really only one major company in the US/Canada that does DALI, most companies have a proprietary way of communicating with their relays in a distributed fashion. I commented on the main video about the different lighting controls manufacturers who provide that control to all buildings in Canada and the US. (required by code to have automatic control now in pretty much all jurisdiction).
Typically you have one master LCU (lighting control unit) or brain of the system which takes in a ton of low voltage inputs from the system (think switches, daylight sensors, occupancy detectors, etc) and decide what relays to turn on/off depending on programming. There is also the whole dimming side of things (0-10v standard) which the hardware takes care of as well.
I really appreciate how you make the effort to show where the wiring is coming from, going to and the route it takes. It gives a feeling of continuity (pun intended) to the circuit and why things are made the way they are made 👌
Puh dun chisssh !😉
For decades I used a standard #2 pencil to manually operate contactors until a coworker reminded me that graphite is a conductor.
I’ve lost my house, family and friends right before Covid and WWIII began. To mentally survive, I retreated into UA-cam, mostly educational or artistic content-like this.
Just wanted to “interact” and show my appreciation for creators like you, thanks.✌️
One of my favorite "contactor stories" was a discovery made in our computer center during a every-other-year power shutdown and maintenance weekend effort. A big UPS system was in the data center with a massive string of 2.25V lead-calcium storage cells in series for (I think) 432VDC @ 400 amps as input to the UPS system.
A giant contactor was used for the EPO (Emergency Power Shutoff) for the entire computer room... red shutdown buttons on the computer room walls were in many locations to push should a major electrical issue occur.
With all computers OFF, the big EPO contactor was being tested, and it ended up failing... it shut the power off fine, but it would not re-energize and close the contacts for the main computer room. Any place to get parts was closed. After a "hilljack engineering discussion", the contactor contacts were forced CLOSED with a piece of wood. All computer room staff were made aware of this naughty bypass, and where the manual power panel disconnect was located should a real emergency occur.
Things ran this way for a few weeks until a new contactor could be ordered and installed; they somehow did it on the weekend and were able to isolate/bypass the contactor to replace it without another computer room shutdown.
No no no, it's not a piece of wood, it's override connection device!
At Cheswick power station we got a frantic call from the barge unloader that the barge mover wouldn't shut down. We killed it with the disconnect, then found that the contacts on the contactor were welded together.
That's a useful life lesson. Never test anything until you're prepared for it to fail!
@@Lemon_Inspector Always have a Plan B too.
I am once again astounded by this channel's ability to make a video on such a topic interesting, enjoyable, humorous and worth watching the entire way through.
It also makes scary topics more digestible while making sure you know it is still scary
"The recess created by the moving contacts provides a visual indicator of the contractor’s *current* state." I see what you did there!
I worked at a electrical supply warehouse for three years and it was a maze of parts and cryptic part numbers without much of an idea what all of it did, outside of the abstract. I do often read articles to satiate my curiosity, but I didn't like working there, so it never passed the threshold of curiosity needed to find the articles.
It's funny that years later I'm now learning what all those things I sorted and packed and catalogued actually do, thanks to you Technologically Connecting me back to the subject.
As a train guy, I appreciate the mention of just how absurd the early DC traction systems of locomotives are. You have a real knack for making this stuff interesting, and informative!
They basically have a giant complicated potential divider below the train's throttle handle I think
@Technology Connections, hopefully you read this. Want to tell you that this channel and content has always been absurdly interesting and that it is because of you I learned more about engineering than I ever thought I would. Please keep making videos, I happily await each one to brighten our day!
Same.
I second that
I've worked in industrial automation for about 10 years now, but my first job had me work near 4160 Vac cabinets... those contactors and fuses were ridiculous and gave me all the scares. Luckily now the worst I've got to deal with is 120 vac after swapping jobs.
Long story short, I really appreciate this channel and have recommended some of the videos to my colleagues who are about as nerdy as me and the new guys because of how well he explains how certain tech works. Keep up the brilliant work!
Years ago I worked in a lab where one of the machines had a switchboard cabinet with a 63A contactor in it. One day we had a specialist in who managed to trip that one. Me and my colleagues present jumped quite a bit but the specialist just shrugged it off.
@@TomFynn People can get used to a lot. There was an electrician that I worked with that was a little more adventurous in some of the higher kcal cabinets, so I can easily see a specialist go "eh it's just another Tuesday"
I actively work in the field, and most of the things mentioned in the video sounded like bread and butter to me, and I've only just realized how little contactors or frequency converters appear in most peoples'' lives. Things like these make up the bulk of many switching cabinets in pretty much any production plant anywhere. These clicky dudes are what make the things go, that produce a lot of the things we take for granted as consumers today.
The part of this video I enjoyed the most was the closed captioning @7:00 transcribing the sound of the AC unit starting as "[BRRGSHSSWMMMMAHHHH]". :) Excellent work.
why would i want a one minute video? your videos are informative, with the dry sarcastic delivery i crave.
I’ve been an electrician for about 35 years, and have done industrial, commercial and residential electrical work. I can’t begin to tell you how many contactors I’ve wired. These days, most things are being controlled over “Smart Systems” so that we can control them over WiFi or Bluetooth and they still use contacts! But your explanation to this audience I found entertaining….😊
Note: a big advantage of solid state/semiconductor relays is that they can switch an AC voltage at its zero point. That is, it can watch the line voltage reach zero in the cycle, and switch at the zero point, effectively breaking the circuit when there is no current whatsoever flowing.
Unless you have non-resistive loads...
@@TheBackyardChemist One could also switch at zero line current...
@@TheBackyardChemist Do tell. I know it changes the waveform around, but it still has a zero crossing?
@@scottfranco1962 With a resistor the current and voltage are in phase, but reactive loads will cause a phase shift between current a voltage. The current zero crossing and voltage zero crossing will no longer coincide.
Neither a mechanical contactor nor this type of solid state switch will work with DC because - obviously - the voltage never goes to zero (of course there's also no phase so current never goes to zero either). HVDC switches have to be much more sophisticated and expensive than HVAC ones. Along with no transformers this was the killer problem in Edison's DC system.
Those lighting contactors make a really nice 'thump', when they pull in!
For high current loads, the old mercury contactors were very reliable. Obviously, mercury presents a few issues, but it did reduce wear.
Also, a VFD video would be awesome.
It's really sad that the room temperature liquid metal is dangerous precisely because it's liquid at low temperatures and fumes a lot.
But if it's covered it's safe from what I recall, so I guess it's probably still used in some electrical applications. I just searched and it is used in tilt sensors, sensibly.
@@KarolOfGutovo Yeah, I decided to extract some mercury from a large, three phase, contactor once and it was not easy. They're pretty solidly (haha) built.
These days, there are silver coated contacts in a nitrogen sealed housing. ("mil spec" contactors, but they aren't meant for 1000's of amps.)
@@KarolOfGutovo Honestly the only really fuss I remember with them was old fluorescent tubes used mercury vapor, so obviously dangerous in the case of breakage, and common consumer appliances that were ending up in landfills.
I think plenty of specialty electronic components still use mercury alloys and liquid in small quantities, it's just far enough away and hidden from the consumer space that no bleeding-hearts have caused a ruckus about it yet.
One problem with these contactors in HVAC equipment is that bugs or other creatures can crawl in between the contacts and prevent proper functioning. I think the older ones used to be more open, but newer designs have put more plastic around the contacts.
Years ago at Elrama Power Station I was sent to see why the parking lot lights weren't working. The contactor was full of stink bugs.
I recall that the origin of the term "buggy program" or "a bug in the software" traces back to the 1940s electro-mechanical computers, where an actual insect was found jamming a relay!
My first job in the Navy (many moons past) was as a Analog computer tech controlling the gun systems on Destroyers, and spent many hours cleaning and re-lubeing the related mechanisms; a chitinous critter in the wrong place could definately ruin my day!
Fortunately, plagues of beetles are rare at sea - more an Army problem😅; Though now I recall, we did have a migrateing swarm of bees try to setup shop on our bridge deck when we in the shipyards of Singapore, caused some exitement fer sure😮.
I too was quite surprised at seeing how open everything is in the HVAC unit. That being said it appeared so clean (free of dust) I can only assume it must be completely sealed from the outside
@@KevinSmith-ys3mh that's a bit of an urban legend; the term "bug" for glitch already existed, which is what made that story from the 1940s notable when it occurred :)
I wonder how many ohms a black widow spider is... 🤔
I had to stop this video one-third of the way through to leave this comment of praise and admiration! I've watched SO many unhelpful electrical videos in recent days that either assume too much or too little of the viewer, and this one hits everything on the head. Definitely a new subscriber, thank you so much for the excellent video and looking forward to many more!
My sister and I drove from SF to Vegas a few weeks ago. It wasn't until the fifth or sixth charge that I realized how much juice was being moved. She was chatting with another Mach-E owner about how some relays fused together.
It was then that I realized how many angry pixies were moving and how they were even angrier because of speed. The engineers behind EVs have a hard problem to solve, and I appreciate how far they've come, so far. When she charged my apartment's monthly power usage in 25 minutes... yeah those pixies are angry, and I was impressed.
I mean, the electric big rig trucks get charged in line with a railroad locomotive or two's worth of power.
I remember my work as electrical technician some time ago. Our mechanics had elevator from factory to warehouse, and they once did something funny and came to me asking for help.
Elevator motor had two contactors, one for going up, one for down. Both had its coils connected via special NC contacts of other one, just to be sure no one tries press both buttons, up and down simultaneously, causing a short.
So, elevator is on the first floor, refusing to go up. When up button is pressed, there's an audible humming and a bit of strange smell. I open the contactor box - everything looks just fine, both contactors intact, properly connected. I take my poking device, and poke the up contactor. Elevator goes up, no problem. I ask guys to press up button, and contactor is going crazy - loud humming, lots of sparks, elevator goes nowhere.
I inspect contactor closer, and its coil is rated for 380VAC. I look at its neighbour - its coil is 240VAC.
So the correct voltage was 240, and 380 coil wasn't strong enough to firmly pull in the links, so it was closing and opening 50 times a second instead, drawing LRA of the elevator motor, creating nice arcs and a bit of smoke.
ALEC!! oh, your hand disappeared in the corner... PORTAL!
Who wants a one minute video on contact us. 25 minutes is perfect, lots of detail and always super interesting. I live for your posts!!!
I work at an older visitor center at Mt St Helens. In the basement is a Snow Melt System. I ask about it and get told “it doesn’t work, never has”. Talked with an electrician the other day and we troubleshot it, and found the contacter is bad. It’s a big one. I’ve been doing some googling about how to repair it, and even though I’ve been a subscriber to your channel for years now, this video popped up in my feed. So, thank you algorithm!
As an industrial electrician, you did an awesome job explaining this subject. Bravo 👏
HVAC student here, the single side shunt can sometimes be used to power something small at 120v reference to ground but is generally frowned upon
Common in smaller units, it is around a third of the price cheaper, though I change them to double pole ones when replacing them, even though I live in a country with 230VAC mains, as the double pole unit as a spare part means you only need to keep one to cover both use cases, and then a second 3 phase unit for bigger units that run on 3 phase, where you have a 4 pole unit typically, with 1 pole also used to power the single phase cooling fan separately. Double pole means less issues with tripping when the wiring outside gets wet, as you typically will have the unit hard wired, and thus simply turning it off will allow you to fault find and isolate the unit. Plus compressors often fail as a short to ground, with split phase the unit might keep on running at part power, till the motor itself burns out the wiring.
Just be careful if you are doing a heat pump, because typically one side has to be wired through. If you do double pole, then you'll have to make sure, if applicable, that a heater for the compressor still works afterwards by wiring properly.
@@sprockkets Lucky for me compressors pretty never need a heater, too hot to ever get them freezing.
@@SeanBZA Um, that would be weird because even in Florida they are necessary.
@@sprockkets Only ever had one unit that actually came with a heater for the compressor, and that was because it was run really hard, with inlet suction at 0C, for a split AC. It killed compressors, and eventually just charged it to around 5C at suction, and it ran a lot better. After all discharge temperature was around 70C on the high side, dropping to 40C when the hot liquid left it, so it was definitely running flat out. Put a large liquid line drier on it to give more liquid volume and a little more restriction as well, fixed cap tubes and not wanting to do the manufacturers designing for them. Left the heater off then, it was a lot happier, just pulling a nice puddle of water from the air instead of the ice block.
Good job of explaining contactors! One minor thing I would add is that they are useful for even low loads when the switch is far away from the line that feeds the load. Having a contactor helps to reduce voltage drop by shortening the wire length needed from line to load. I use this approach to power my pool lights, for example.
UPS technician here. Contactors are essential to a modern UPS, as well as a static switch, which is a solid state contactor of sorts.
man and here i thought you just threw the boxes into the back of the truck and drove away
@@KairuHakubi There are two kinds of people in this world. Those who hear UPS and think mail, and those who think PC parts lol
@@sphygo (of course I was making a gaggityjoke, I knew what he meant, though it took me a second. i'm kind of surprised uninterruptable power supplies have their own technicians)
It's amazing how quiet they are now. You can barely hear them switch over.
@@KairuHakubi Probably because you're thinking a the wrong end of the UPS scale. The kind of cheap, simple, often offline, UPS systems you'll buy for your PC are rarely repaired (like most consumer electronics). Larger, more complex UPS systems are quite complex, quite expensive, and there are certainly a lot of techs that specialize just in that. Think the kind that are used in, for example, datacenters. They cost absolute fortunes, and can be absolutely massive.
I was absolutely stunned how easy you could pry that Eaton contactor! Here in Europe, opening such a thing up is hardly possible and usually requires destruction. At least, the types I've opened up where not at all made to be serviced and had to be destroyed up to a point you would not be able to use them anymore.
Last week, I was instructed in the course to automation technician to disassemble a contactor and find out the order number for a spare coil in case it got burnt, and then the number for a coil of a different control voltage.
Never having taken one of them apart before (but aware that the difference between opening those plastic tabs and breaking them off is really small), I carefully went to work, separating each and every component in the entire contactor while finding out exactly what parts kept each other in place.
Having located and freed the coil, I tried to look up the numbers stamped on it, but google wasn't my friend, so I took the whole pile to the teacher to ask where the heck I could find the requested information.
Turned out that, just like you said, the A-series of ABB contactors aren't meant to be serviced lmao
Teacher asked where I found it (that box of them we use for motor installations) and only then get informed that they have some old ones just for the exercise I was doing I once again got told to stop destroying school property as the contactor I had taken apart couldn't be reassembled.
Wise from my previous experience when I had to disassemble some additional circuit breakers (hence the "again" part) to figure out exactly how all pieces fit together, I just grabbed another contactor from the same box and got to work.
If I do it again, it probably go a lot faster as I'm now familiar with the construction, but to sum it up, contactors that are meant to be replaced CAN be taken apart to be serviced, but it's not worth the extra time and hassle.
@@johanmetreus1268 Ofcourse contactors with contacts that are meant to be replaced can be serviced. But the contactor he shows in the video would certainly not be one you would find serviceable here in The Netherlands/possibly whole of Europe, but in general we also don't have the contacts to the coil at the sides of these things, but always below or above the power-contacts.
Whether it's worth the extra time and hassle depends largely on the type of contactor, the availability of parts and downtime that is deemed acceptable: if you don't have spare parts but it's absolutely necessary to get the system the contactor is in running again, a good cleaning of the contacts good bridge the time till you do get the spares in.
Usually the bigger the contactor, the more worthwile it is to service it.
Advice for everyone: if you want to find out if a contactor or other electrical part is serviceable or not: look up the type/modelmarking on the unit first. You'll usually end up at the manufacturers' website, where the absence or availability of spares will tell you something ;)
I enjoy the closed captions on these vids so, so much. I really feel like I really know which things go fwhoomp and CLACK.
As someone who works with industrial equipment it is indeed very satisfying to be able to just press a small button and hear a nice clunk as the equipment powers on (in our case the contactors are powered by 24V, which is under control of the safety system, if the safety PLC detects an error you won't get high power)
On industrial contactors you can often attach a kind of switch to the moving part that can give signal back to the PLC telling if the contactor is actually engaged, or if it is engaged when it shouldn't be. Some contactors also need a helping relay because they draw too much power from PLCs og control boards.
Watching you explain stuff gives off chill teacher who doesnt take himself too seriously vibes
@Ithecastic I think your vibometer might be broken.
@Ithecastic You wanna draw me a line as to how you got to that conclusion? Because I sure don't see it.
@Ithecastic I dunno. 'chill' by no means has to mean lax and, and I find teachers who actually try to make learning fun and engaging to be much more effective than teachers who are uptight and serious all the time.
Sounds like you may be projecting just a bit due to some bad experiences with lazy teachers in the past.
Unsolicited armchair phycology sure is fun, isn't it?
I’ve never heard so much discussion about which color wire does what since the last time I saw a movie about bomb disposal. Now that I think of it that would make a great episode on this channel.
I work for a major industrial refrigeration company in the US (you’ve seen our stuff if you’ve been to Walmart, Kroger/Fred Meyer, Target, etc.). We are starting to use more VFD’s on our refrigeration rack systems to control compressor motor speed keeping energy efficiency up. Really cool (no pun intended lol) to see you mention this stuff! We are also beginning to introduce CO2 refrigerant into a new product line of ours because it is more energy efficient and better for the environment compared to R440A or R448A. Love to see these changes taking place!
Fantastic video! I work with lighting controls, and contactors are something we design with every day (using our system to add a "brain" to them), and there are often large panels full of multiple contactors we interface with. Some of our newer team members have had trouble with the concept, so I'm definitely going to be sharing this one with my team!
The star/delta configuration described at 15:59 reminds me of series/parallel controllers found in old trams and electric trains! To start from a stop to low speed the motors are wired in series so they split the voltage between them, preventing the motor coils from burning out, then when getting up to speed the controller switches so the motors are in parallel and get the full voltage each to safely run at higher speeds.
EDIT: you briefly mentioned DC train control after I wrote this comment :)
The older NYC subway cars have a 3 position controller - switching, series, and parallel - I never did learn what the switching position did, but have read that if you left it in that position for too long, you could burn out the train's giant resistor grids
For DC traction motors, starting in series is less about preventing motor damage and more about breakaway torque.
I just love this channel so much. I love learning about stuff that I would never even ask myself how it works. I love your writing and your jokes and the way you deliver them. Just great. Thank you!
I love how you explain things so simply and with plain language. It's very accessible without being condescending. Very well written. Great job! Keep up the good work. I learn a lot on your channel.
I can still recall the exact day my lifelong fascination with science and technology and engineering started.
As a kid, I happened upon an age-appropriate book on how home electrical wiring worked. Fuses, insulators, transformers, circuits, power generation and transmission, etc. Prior to that, like most kids (and probably like many adults even now) the world had just been unexamined, and kind of written off as working by magic or whatever.
While reading that book however, a metaphorical lightbulb went on (ironic), and I suddenly realized that things made *sense* if you took a moment to look into them, there was a logic and structure to the world, and people could and did apply clever planning to put together elegant working systems. I've spent my life ever since seeking out knowledge and learning how to make things work.
The style and content of most of your videos bring back for me that youthful sense of "aha!" and fascinated wonder, thank you.
I'm so glad you're putting up these videos. I'm a control systems engineer who works with this stuff a lot, but I've never known the inner workings. I knew a fair amount (since this is my field) but you still managed to teach this old dog some new tricks. Thank you many times over.
Very timely! I just had my HVAC go non-functional because of ants getting up into the contactor and preventing the circuit closing. Now I have a name for the device that the HVAC guys wanted to charge me $300 to replace, even though a bit of canned/compressed air is "good enough" to clear it. Thanks! ❤
It's like $25 for a new quality contactor.
The contacts are most likely burnt up from making a poor connection with high resistance. You may want to just replace it, unless you can go without AC while you get another.
To keep the ants out you just shake borax all over the base of the AC outdoor unit, and on the base of the electrical connections. Redo every year, and you will never have ants again. Same for electric gate motors, I keep a bag with borax, another with blue death and a can of spray for the quick removal.
To be fair to hvac guys, there's a minimum cost to make the trip, and to verify that it's just the contactor & not something else. Feels like crazy markup till ya think of the cost to roll the truck. Such is life for all service work.
Spicy ants!
Ohhhh now it's starting to click for me
I appreciate the effort to properly subtitle the blooper reel with the actual sounds produced.
Literally, only you could make a relay so enthralling. I hope this comment boosts engagement.
Thank you for finally explaining what the actual difference is between a contactor and a relay. It's something I've asked people several times before, and never been able to get a straight answer.
I work as an industrial electrician, lots of times working with huge contactors from the 60s-70s. Super cool to see you do something like this man, great video!
For the hotel example, if the items and their breakers are spread all over the building then it will mostly have several different contactors (usually one per breaker) and all the contactors are operated as one from a central control circuit. You could run hundreds of contactors from one control circuit spread across many different breakers in many different locations.
From personal experience larger buildings use impuls switches.
Yep, I'm pretty sure it's not kosher to run stuff on different breakers in the same multi-pole contactor. Never bothered to look it up, wouldn't have a reason.
I can see that multi-pole monstrosity being used for stadium light poles though.
In that case, it's actually done throigh relays. A breaker will typically be 20A, with voltage ranging from 120-347V for single pole applications. Most lighting (apart from highmasts and some warehouse lighting) are all single pole fed. So contactors aren't actually required, or used. It's all relays controlling zones of lighting all fed from a central LCU (lighting control unit)
I worked in a large retail building and it was fun being there in the morning. Different areas of the stores lights would turn on over the warmup period. My boss had a breaker box in his office and you would hear a lot of the breakers or contractors kick on every morning. I know that they had some kind of central control but I never bothered the electrician on staff.
@@c31979839 For most of the commercial lighting control work I do, I use relays with 25A rated contacts usually fed from a 15 or 20A circuit. Our company got away from using contactors since most people are irritated by the clunk and hum they make.
16:30 “one of my favorite contactors” I doubt that phrase is spoken very often 😂
You have some of the only long form videos that I still watch. Thanks for the efforts.
Took s few coklege classes in this for my ME degree, and after having worked in a shop setting with alot of heavy equipment and regularly changing out broken contactors, wye delta starters, and programming VFDs, i can say i really appreciate this video
I was hoping for the day you can fully explain contactors. Its something i was fascinated when learnt from them on school and its nice to show appreciation for one of the keys of analog automation for electric systems
Great timing! I'm making a UPS system for my friend that swaps between normal and backup power without the UPS needing to provide full power, especially in normal operation. It removes a few advantages of the UPS like power filtering, but it can be mitigated with external solutions for a fraction of the cost of a larger inverter. His house grid is a three phase system, but I've decided to only power two of them in the case of an outage by splitting the output of the single phase UPS as there are no multiple-phase appliances in his appartment to suffer from that and one of the phases powers only things (clothes dryers, washing machines etc.) that aren't really prefferable to feed from valuable battery storage. Contactors are pretty much the best way to do that and I love them.
For those curious to know other uses for contactors. I decided that I wanted better control over a pool setup that was run by a simple Intermatic pool cabinet w/ a mechanical timer. Most pros will say install a pool controller unit, but the grift is that most are over a grand. So, wanting to integrate some automation into my setup, I gutted the mechanical crap, installed a 30A DPST 120Vac coil contactor and used a z-wave Aeotec ZWA038-A as the coil switch and presto; one schedulable pool pump w/ power fail last state and manual over-ride. Replaced the lamp w/ 50w LED and a dusk-to-dawn relay and all told, paid 1/10th the cost of a panel overhaul. Only catch... as the pool is in AZ, I needed a switch that's tolerant of higher than normal temps and the Aeotec was the only one rated to 50C, whereas most only go up to 40C. Since this is also an automated setup, there are other "safety" protocols that have been put in place, such as overheat and freeze protection. As an aside to this, I recently rigged an over-pressure switch/contactor (you find these on water wells and hot water circulators) w/ a z-wave contact sensor to protect against filter blowouts. I may have a simple pool setup, but you can imagine the possibilities for those that are not so simple.
In a warehouse I used to work at, the automation kept having contactees fail. I remember the answer I got when I asked what one was.
"It makes contact" was all I ever got, so helpful video.
I'm an HVAC technician, specifically a reefer technician. I love all your videos
For some weird reason I absolutely love the sound of automated relay/contactor clicks. There's a detailed video of KITT's scanner (Knight Rider) out there where they put the camera up to the control box, and if you know how fast KITT's scanner scans, you can just imagine the sound of the relays going.
Me too. By coincidence I made a video today of a level crossing at a trainstation nearby where the relay-cabinets are accessible to the general public (read: not open or anything, but usually they are besides the tracks, surrounded by fences, making it impossible to come even close, this one is right beside the platform-walkway). I walked by one once and was surprised how well I could hear the relays going.
So today I made a special recording of it. It was so nice to first hear the significantly bulky 'clunk' when the announcement-section drops and activates the crossing, which in turn starts a whole concert of click-clacks at different speeds as - in contrast to most other crossings on this planet - Dutch level crossings usually consist of multiple pulsators (? see below) that are (I never liked it) not in sync. From what I've read this is a redundancy thing, so a pulsator that breaks down, does not completely disables the flashing nature of the red lights at a crossing.
? pulsator? No idea what they are called in English, but they deliver the pulses to make the lights flash in an alternating fashion. Either we called them EOR45 and EOR90 (Probably standing for Electronic Oscillating Relay, with the numbers stating the amount of pulses per minute or this abbreviation was derived from GRS, the company where we got most of our railway-signalling electronics from in The Netherlands.
Just like the elevator at the company where my dad worked. As it would go up you would hear a 'click... click-click... click........ sequence as it passed another floor.
I also made a three-way junction with lights at school as I was learning to become an electrician. I had to get extra cables from the measuring-department and it used up all available switches and relays from the practice-board, but it worked. The only thing it didn't do was provide a crowbar-situation should a relay get stuck and than provide a conflict-situation (green from two conflicting directions). In the past, this would cause a short, rendering the junction to fall back to flashing amber. It's all electronic now.
those would have just been relays, but yes I can imagine the waterfall of sounds as it "scanned". I've got a 8 pole attenuator here that can cut in 0.25 through 32 db of attenuation on 8 relays, but it must be switched with binary. made an arduino sketch to tie it to a simple pot, and you can imagine the sound it makes if you quickly spin the dial. (256 states)
Sorry to be that guy, but those wouldn't be relays but transistors, those weren't new in the 80s, and before vacuum tubes would be used for fast applications. Relays would be used only for the final switch of the electric actuators that control the car because they're not really fast
@@bene5431 Uhm... TdGalea talks about the 6-lamp scannerlight at the front of the car...
As an industrial automation, and maintenance technician, this is a very good video for new guys in the field. I love UA-cam. Thanks Alec!
Love that you went in to Delta-Wye. Next step above Delta-Wye before you get to full on VFDs is SCR based soft starts which could make for an interesting video because it is similar to how old school dimmer switches worked and you are more in the household cool things vs industrial cool things. Then you could also get in to zero crossing and random crossing AC SSRs... or maybe that's too out there. Also SSRs are actually stupid cheap these days. Thoughts from an industrial EE.
My friend had her air conditioner go out yesterday. I figured I could at least check the capacitor, but that checked out (shocking, since it's over 25 years old and we get huge temperature swings). Then I saw the contractor and recognized it as that thing in the TC video from a year ago. It actually sparked when I turned on power.
Looked a little closer and realized the part I thought was a weird (maybe fried) connection bit was actually a weird (definitely fried) bug that made a home under the moving bit. Moved his corpse out of the way and the thing fired right up!
Thanks for teaching me about contractors so I would bother to look at one. Saved my teacher friend a lot of money when she was afraid she'd need to replace the unit
It's always exciting when you overload a contactor and weld the contacts closed. You have to work fast to catch the magic smoke.
Thanks for sharing!
I'm glad you made a mention of contactors for rail equipment here, high current DC comtactors (particularly those used to control energising catenary wirres) are huge and demand respect.
Fun Fact about computers:
- In the old AT design, the Power Button directly switched the main voltage wires of the power supply.
- But in the ATX design, the power Button switches a relay on the motherboard, that in turn switches a connector in the PSU. One advantage is that the computer can turn itself off after shutdown (AT ones could not do that).
And once you add a bit of Standby Power, we can have features like "wake on keyboard", and even "wake on LAN".
"It's now safe to turn off your computer."
@@renakunisaki Exactly 🙂
Actually, ATX power switching is a bit different, and I have never seen a power relay on a motherboard.
Upon registering a power button press, the motherboard will pull down the PS_ON# signal in the ATX power connector, an active-low TTL-level affair. This turns on the power supply. (Standby power thus is an integrated part of the whole operation. There is usually some debouncing and logic between the switch input and PS_ON# output, I think this is mostly handled by the Super-I/O these days. I imagine it would have been little more than some basic debouncing back in 1997 though. And if you just want to turn on the supply manually, you might use a paperclip or similar.)
Once output voltages are within tolerance, the power supply pulls up the PWR_OK or "power good" pin to tell the board that power-up can commence. (If you've ever encountered a dead PC with "lights on but nobody's home" syndrome, that's generally an unhappy power supply.)
Upon a regular shutdown / suspend to RAM event, if "power good" ever goes down or during emergency shutdown being triggered by overheating, the board will let go of PS_ON#.
For all the gory details, you can look up the _ATX12V Power Supply Design Guide._ The latest version is called _ATX Version 3.0 Multi Rail Desktop Platform Power Supply, Design Guide,_ though I don't think there have been any changes to these signals in absolutely forever (except nowadays the supplies are required to handle a lot more power cycles as Modern Standby = S0ix may involve periodic waking).
As a British Electrician/Plumber/Massive Nerd, I do find the videos where you give description of your heating systems quite fascinating. Your ducted gas furnace systems with in-line aircon evaporators, are essentially a scaled down version of the AHUs we use for commercial premises.
Now try asking why the difference exists. I'm not sure, but I suspect it's to do with house size: Air ducting takes up a lot more room than water pipes to move the same amount of heat.
@@vylbird8014 WAY more older house in Europe, and it's a whole lot easier to retrofit water lines vs. air ducts. Hence more mini-splits & boilers than we see in the US, especially in the Midwest where both heating & cooling are pretty much universal.
Not to mention our penchant for idly sending 230V power to a heating thermostat
@@JamesScholesUKYeah, my old home has a 230V Thermostat controlling a bank of kontaktors that power a total load of up to 20kW.
Hot water and steam systems used to be extremely popular here (hot water still is in certain areas, eg New England), but fell out of popularity in most new construction in favor of forced hot air in the late 20th century, mainly due to it being more cost effective to have air conditioning and heating share the same system
He's absolutely right. There's a right way to learn about arc flashes and a life lesson way to learn about arc flashes.
At the fire department there’s this really old siren there and it’s also controlled by one of these contactors and to activate the contactor, there’s a simple light switch and that sounds the siren. However, sometimes the contactor gets stuck so we have to cut the power to it move it a little bit to get it unstuck, and plug it back in and flip the switch to get it sounding. Now we only sound the siren on special occasion like the Fourth of July so it’s not exactly maintained but we keep it unplugged whenever it’s not being used so it’s fine. And besides, the siren doesn’t sound sick or anything it sounds perfectly healthy and fine as if it were brand new.
vid?
This reminds me of the time I had to do a deep dive into contact materials for these things. They often use contact rivets of silver tin-oxide or similar mixes of silver and some oxide to prevent premature failure. Especially contact welding is something you want to prevent at all costs. The standard material choice used to be silver cadmium-oxide, but since heavy metals are not so nice to have everywhere researches had to spend decades to develop alternative formulations that could compete with the poisonous variant. Quite similar to the whole lead-free solder thing.
I love your jokes and how you go in depth into each topic! 20 minute mark, I would sit through a 20 hour seminar if you were giving it!
What I saw on a gondola lift recently was that there was a secondary smaller electric motor, to spin up the main motor in order to overcome the locked rotor
Our warehouse has a fun old setup of relays and contactors. One switch will start a cascade of contactors all initiating after each other (to not overload the main fuse) with fans and lights. That lovely "Click - Hum - Click - Hum - Click - Hum" rhythm makes me always smile.
Never ever change, I cant't stand the 1 minute videos, they allways make me want more
Would not have imagined there was a whole video's worth of content on contactors!
I love learning from you. It’s the perfect blend of info, dry humor, and interesting tangents at the right knowledge level for me to truly absorb.
I’ll have to listen for the clacks in more places now that I know, but I have to admit the wildest one was the kachunk a Tesla makes as you put it into a drive mode. I actually had to ask what the hell it was because it was pretty surprising and I wasn’t expecting mechanical sounds from an electric drivetrain.
I’ve also had to deal with the unfortunate situation of having no AC at my house, and I went out of my way to buy “inverter” window ac units so they spin up gradually and somewhat quietly compared to the clunk of a regular unit. Im glad this type of variable power control is filtering down into mainstream appliances as it’s so much nicer and as you mentioned, more efficient than the old kind.
I'm an industrial I&C engineer. Solid information.
This 01 Electrician approves of this content!
Just did a little under 3 years working on conveyor systems with most of what you mentioned. VFD (variable frequency drive) are pretty standard now. You can save power and extend the lifetime of the motor. On the operational side, the control systems can do amazing things with VFDs. They can control and monitor the belt speed to such a degree that orchestrating dozens of baggage lines as they merge, split, and stop/hold baggage for security reasons is a matter of programming via laptop in a tiny room between the bathrooms in the bagwell.
Thanks for the content!
PS: overload protection is the primary distinction between a contactor and moter starter
As someone getting more and more into industrial automation, this was a treat. I've always loved your videos but this one I can relate to closely.
Would you consider doing a video on PLC components sometime? That'd be cool. I know there are _tons_ of different ones, but maybe something like the basics of a PLC, or PLC fanless computers vs a standard computer. There is soooooo much to learn about it and I'm excited to really get into it.
Get a true understanding of electromechanical control systems, building logic circuits with relays.
Start program the PLC in Ladder (one of the five standardized languages) and you quickly notice how a latching circuit equals a bit of memory,
Switching to Fb (Function blocks, another standard PLC language), and you'll discover how OR equals contacts in parallel, while AND is contacts in series.
Once you have those two down, you can then use lL or STL to speed things up as you can just type shorthand commands instead of dragging the graphical symbols around.
I use these when assembling control units for actuators.this is going to be fun to learn exactly how they work! Same brand as well! Although the ones we use are longer
I smiled when you pushed that in to manually override. We've done fun stuff like this... except, moving elevators up and down without the logic being aware in the slightest. (more older models however) :D
That sounds like a hilarious prank to pull on your unsuspecting coworker. Newer models of elevators should hopefully have some feedback sensors that will alert the controller to a non-standard movement event.
@@EmptyZoo393
Definitely! Their all more or less operating systems at this point. Not what they used to be (just a few relays and contractor wired in intellegent ways made a lift logic in the day..)
So definitely if something moves out of the ordinary it might just go crazy, but hah, it's one of those things where different logics might react differently and that too would actually be quite interesting to see :P
In college I worked at a large entertainment & sports arena. My role meant I had master keys, so I took it upon myself to explore and learn all of the building's systems. The lighting control was interesting for its day... It was controlled via a Windows app connected to relay cabinets attached to the bottom of each of the lighting panels throughout the building. There were a few easy presets to turn on the exterior lights and each type of indoor light and the facilities team could make individual adjustments if needed.
Years later, I worked for a large museum which converted to a similar system that added a relay cabinet next to the existing lighting breaker panels. It was also networked, but we had the option of hitting a button on the relay cabinet circuit board to make manual changes. I'm sure that building's owner had more capabilities than we used, but they had too many other problems to worry about customizing our lights. :)
One thing I did learn was commercial building lighting often uses 208v to save copper on long runs of lights. This is why manual light switches in those buildings are usually a bit stiffer with a more defined click; they have to be rated for 'high voltage.'
I've installed hundreds of not thousands of contactors in residential, commercial, and industrial applications. They're fascinating, a brilliant application of engineering. The clunk you hear on your ac compressor right before it starts, or, in a empty stadium, clunk, a group of lights come on, that's the electromagnet activating and releasing or pulling the contacts.
Hey Alec, can you make a video about how an electric train/metro/tramway is powered? And how the tens of thousands of volts get supplied over the long rail route?