i watch you to learn English i am an electrician and this channel really helpful to improve listening skill and increase vocabulary memory when i hear a vocabulary or idiom that i never heard before i can guess what do you mean because you are talking about my job when i was an apprentice i was in trouble with contactors and relays
mefista free glad you’re not making excuses acting like it’s impossible to learn English like 90 percent of ppl who need to learn English for a good career
Hi im 23 y old from sweden. Currently im rebuilding a mig welder, everything except the transformer is getting replaced. Now i need to control gasvalve, Wire feed speed and transformer with the mig torch as the main switch. I have a plan, but i just want to give you props for your work. Always good clean easy to understand information and no BS. Keep it up! Cheers from sweden / Jesper
My favorite use for contactors so far were in an autobody shop that had 12 garage doors all on automatic door openers. When the technicians (or anyone) drives up to the garage door, the door sensor opens the door and they drive in without getting in/out of the vehicle. At the end of the day when they close up shop, the shop light switch also feeds to a contactor that interrupts the garage door circuits. When the lights are off none of the garage doors will open at all. There is no power going to them, cut off by the contactor. It's not really that complicated, but I thought it was a very clever solution on how to lock 12 garage doors easily with the least amount of effort
wow. anyone that calls themselves electricians. should already know this stuff. he is a great electrician. but nobodys the best of anything on youtube. dont church it up
you left out one of the most important roles of contractors, especially those used in industrial machinery situations.....if the machine loses power...for any reason....the (non-latching) contractor will prevent the machine from restarting when power returns.....working around rotating equipment, this can be life saving......
Back in the eighties, when I was learning about this, I was taught to look at the contactor like a knife switch or door. When the knife or door is closed, then, it connects; whenever the knife or door is opened, it disconnects. 🚪🤓
Thanks for all the good info. Here is a slightly different way of thinking about the same things you've said. Spoiler alert, point 4) is the real differentiator between a relay and a contactor. 1) Both relays and contractors are passive power amplifying switches. On a relay, the control currents are typically measured in milliamps and the voltages are typically < 24 volts. The output currents are measured in amps and the voltages are < 240 volts. On a contactor, the control currents are typically measured in 100s of milliamps and the voltages are typically < 120 volts. The output currents are measured in 10s or 100s of amps at voltages of 120 to 600 volts. 2) Both relays and contractors can be used identically in logic situations to implement boolean logic as part of your control system. 3) The main thing that distinguishes a relay from a contactor is how they are made inside. Both relays and contractors have arcing problems (which erodes the points) when the points of the device open and close under load. In a relay, "normal" material and switch design can be used and still provide a life of 10s or 100s of thousands of operations. In a contactor, "special" material and design must be used to provide a reasonable number of operations before the points wear out. 4) A second differentiator between the two is how the internal connections are made. In a SPST relay, there is one set (pair) of contacts and the armature (the part that moves and actually makes contact) is live (i.e., is connected to one of the output terminals). In a SPST contactor, there are two sets (pairs) of contacts and the armature is dead (i.e., is not connected to either output terminal). When a contactor is activated, the armature causes both sets of points to contact and the output current then flows through the armature. But the armature is never directly connected to either output terminal. 5) Point 4) is driven by power design considerations, but also provides a level of safety for high power circuits. This is how an engineer (at least this engineer) thinks of these things. This electrical engineer also put himself through college working as an electricians assistant and still maintains a high level of respect for master electricians who are dedicated to their craft.
Hi, I really worked with enough mechanical and non-mechanical contactors. for mechanics and had to use relay to be able to unlach. Today I tried to convert a mechanical one like the one you show in the video so you don't have to use the relay but when it was connected it was not fully connected, it just jumped continuously, I think it is coil separation. I returned it to its normal state and it worked perfectly
Thank you so much for this video - this really helped me understand exactly what a contactor is and how it works! Great video and I love that you explain is so simply!
I've been watching video after video about contactors and relays. You are the 1st to explain the fact that a regular light switch can be used to send the signal to activate the contactor and deactivate it.I live in Lima, Peru and don't speak a lick of spanish. Just trying to find 3-way and 4-way light switches has been a pain.
For both relays and contactors the time things get really confusing is when you have a system (typically safety related) where the contactor or relay is normally energized unless some condition exists. Basically reversing the no and nc roles, generally so a loss of power or break in the wiring also triggers the safety action
Great video I'm a 1st year apprentice and we were installing these yesterday I'm omw to work right now trying to learn I asked what they were and the guy showing me said it's so the lights can come on at the same time. Immediately wanted to know more about them
I'm doing a 50amp emergency shutoff for my server rack. A mechanically held latch for it makes the most sense since I would need to shut off more than 1 circuit.
I like your gestures and your actions when explaining on your topic, you are so energetic and what I can see is you are so very professional. We have similar contents and I compare myself to you as I am only a beginner student. I hope my channel will be like yours even just a little bit so that my channel can help others like yours. Thanks for this very professional tutorial video sir.
Yeah. You should do a video with light switch as digital field device to simulate a pressure switch , temperature switch , level switch, flow switch, etc. Then use light bulbs simulate motors, heaters, magnetic 24VDC/120vac valves, status indicating lights/feedback, etc. Then throw in some timer relays too. Like if the system doesn’t see pressure at certain time then have relay pick up a light for a fault. Then you can design and draw basic digital paddle logic control circuit for young electricians. Then they can see how the current flow throughout the control circuit system through and how the basic automation works. Sweet video man. You’re giving people free knowledge so they can put food on their kitchen table. 👍 keep them coming.
I watched all these videos several months ago, I mostly forgot them, but I am going to rewatch them. Watching this video the second time around, it makes more sense.
w hen us ed to operate an electric motor, usually with overloads, you have a 'Mag starter'. pressing the ON energized the coil and pulls contacts together, BUT if the motor is overloaded either a magnetic coil/ or heater coil opens a switch through which magnetic contactors coil's current goes through and the circuit is opened, contacts to the motor are opened and the motor stops. it is the current the motor draws that passes thru the overloads. If motor draws 15 amps, at full load then, with a greater load more current is drawn and that extra current drawn causes more magnetic pull or heat on the overloads that causes switches mated to overloads to open the contactors coil current.
Good video. You should have mentioned for the beginners how to test if the a contact is NO or NC if it is rubbed off do to age. Not every one or application is going to have brand new contactors or relays to work with.
De-energize the control circuit, and ohm-meter the line and load terminals of each phase. If you get zero ohms, it is normally closed. If you get infinity ohms, it is normally open.
This is an excellent explanation. You didn't mention anything about the current draw for the coil, but I'd imagine it's relatively low. That also explains why one would use a relay to control a contactor. If your control signal were at digital logic levels, say from a control board, you'd need to use a relay to switch the higher voltage that controlled the contactor (not to mention keeping any voltage spikes away from the much more sensitive circuitry).
With contactors and relays you can do a lot of thing, show lighting, automatic transfer switch for Utility, Solar, Generator to house circuitry. Schneider is the best brand to do it.
I think this topic would have been really helped by you having your multimeter handy in continuity mode, and show the NO/NC difference. Even so, just the verbal was a great overview!
After 35 + years in the trade, nothing scares the shit out of apprentice more is trying to troubleshoot a 12 pole contactor with all the wires etc. and yet it’s very easy to check
I also watch a video about electrical circuits and power controls in English like this to help me in the subjects I teach at the technical high school with bilingual teaching (Portuguese / English), mainly with vocabulary and pronunciations - greetings from brazil
Great video. I'm currently working on a project where there is an existing 60 amp lighting contactor being fed from a main panel and has the load side of the contactor feeding a sub panel they're using for lights only. It's a duplex apartment and during renovation a lot of wires were cut including the "master switch" that shuts off every light in the apt. I traced the master switch and it is actually wired to 2 small guage leads in the contactor. I'm assuming that's the coil which will close or open the contacts. I'll give this switch its 120v and see if it will actually control the contacts because as of right now, this contactor is normally closed and every switch would need to be controlled independently.
At about 9mins in the video you speak about mechanically (latching) contactors. Can you control latching and unlataching mechanism with the same control circuit or do you need two different circuit to lastch and unlatch? Any help would be greatly appreciated. thx man
The purpose of the high leg system, is when you have primarily 240V loads, whether single phase or 3-phase, and you still want 120V loads to be available for lighting and general receptacles. It works best if the KVA of the 120V loads is a small minority of the total load. If you use a 120/208V wye system by contrast, you loose 13% the voltage that would otherwise be available to the majority of your loads. Each phase is 240V away from the other phases, but something special happens between A and C. The transformer winding that produces phases A and C, is also centertapped to produce the neutral. This is where you can power your 120V loads. Consequently, the B-phase is 208V to neutral, and for all practical purposes, don't count on using it for any single-phase-to-neutral loads. Reserve the B-phase for 3-phase loads, and phase-to-phase connected loads. Most single pole breakers are slash rated for 120/240V, which means 208V to ground would not be allowed. You'd need a 277/480V panelboard, to be able to use the high leg-to-neutral. It is a requirement in the current NEC, that the B-phase is the high leg. It used to be that the C-phase was the standard for the high leg, and you may find that in old services. Some utility meters may also require a C-phase high leg, even if the rest of the building is B-phase high leg. The recommended practice to working with one of these systems, is to produce a single phase subpanel, off of a branch circuit on phases A and C. Avoid putting your single phase loads in the main panel, and strategically put them in the single phase subpanel. Put only 2-pole and 3-pole breakers in the main panel.
What load were you trying to control? They make photocells/time clocks that are rated for loads. I've only installed contactors for complicated scenarios or large loads. If you have a normal load you can find a single device to control it. No sense on installing a contactor and photocell when you can just install a photocell
Have an auto start generator set with a normally closed contacter. How? Have a single pole NC contacter on the mains to keep the circuit open, so when the power cuts out the contacter closes a circuit signing the generator set to start. There are other mechanisms, circuits, and systems that will most likely be implemented too. Perhaps a “generator ready” contacter to signal that the current is stable. A generator off mechanism is a must though
Another good one - thanks! I first heard about contactors in HVAC videos -- specifically sending a low-voltage/low-power thermostat signal to a high-voltage/high-power compressor circuit. Contactors are great because that way, you don't have to send 240 volts through the thermostat on your wall -- 24 volts will do for that. Keep these great vids coming!
Got a potentially dumb question but With a 120v coil do run a hot and neutral to it.bc I have An A1 and A2 on the coil I know a1 and a2 are just opposite sides of the coil just asking bc seems like it would short if I did that but where does the neutral for the line side go?
Thank you. I was trying to figure out what a contactor was because they came up as related to a cable float. I'm trying to figure out how to get a better system for my potable water cistern to tell the pump that fills the cistern to turn off when the cistern is full. I currently have a D-box switch with a rod attached to a float. Unfortunately, the rod keeps getting stuck in the down position & the cistern overflows. Someone recommended a solenoid valve or some other setup. I saw some cable floats that will signal when they are below a certain point and above a certain point (not exactly sure when they send signal). I don't think I can attach the float's wiring directly to the pump's wiring, but I could be mistaken. My pump is 1HP V 115/208-230. The motor does not list the amps. Would I need some sort of contactor in between? Would I need normally open or normally closed?
Hey Dustin, so when you speak about coil. Is this where you usually land the timer switch? But the line side from the panel still gets landed on top of the contractor then load to the bottom? Thanks for all your videos!
I have a weird 12 pole mech latch my boss found with a relay does the unlatch. It's a tiny relay in the bottom corner. Haven't quite dug into it completely ......video was helpful tho as far as the unlatching explanation. I'm used to the magnet. He always finds some weird shit thru the square d rep. And the money he saves on the part, he loses in me reading diagrams lol.
Thank you so much for this video, but I didn't find what I was looking for. I need something that's like a rotary-switch and latching-contactor had a baby. So every time I tap an Up button, it switches different circuits on & off, in ascending order, to a stopping point, and if I tap a Down button, it will only turn on those different circuits, in descending order, to a bottom stopping point. Does a mechanical device like that, already exist? I have searched for: Racheting relay contactor, shift drum relay contactor, sequential relay contactor, sequential manual transmission style relay contactor, but still didn't find what I need for a high current sequential switching project, using just 2 normally open buttons.
If you're a hobbyist it sounds like you need something like an arduino. Some kind of logical processing unit, or PLC. There is no reasonable easy way to do this with only contactors and wire
I have a couple questions 👋🏽 let’s say I use the 3 pole contactor, can I use one of those lines to “control” the coil (obviously before the “load” side)? Or do I need to pull a different source of power?
My 12 volt contactor does nothing, and I tried reading the resistance and it was not conducting any electricity, it did absolutely nothing, does that mean it is broken?
So for example, would a contactor be used when you want to have alot of lights drawing a large amount of amps controlled by a switch? But since a regular 15amp or 20amp switch can handle that many amps you use a contactor in-between?
Hey Dustin. I love your videos. It's why I got into this trade. Im newly graduated with my ET card# in California. I have a question for you. Do you have an email?
I usually use the good old fashion analog timer that’s on a battery backup. It’s tried & true😉 Thanks for the vids Dustin. Wondering if gonna do some tool reviews as well, as really liked when you did that (unless not for this channel & it’s a Journey2Master thing.....but is this channel dead; cuz I SO hope it’s not🙏🏼) Cheers✌🏼
Dustin, Well done again! A few comments. Relays 10 amps and below, contactors 20 amps and up. Mechanically held contactors have coil clearing contacts to cut power from the coil once changed. NEMA(USA standard) (black) rated contactors good for 100,000 operations, IEC(European standard) (white) rated for 10,000 operations. I hope you do not mind the additional information! I hope electricians aren't really connecting coils without checking the voltage first! Respectfully, Kevin
I really enjoy your videos, makes me want to be an electrician again. I took electrical in high school but once I got in the work force I couldnt find an apprenticeship for it. Ended up getting into hvac with the promise of being apprenticed but that is turning into a shite show. I been working here as a helper for 3 years. I think its time to start looking into being and electrician again, what I originally wanted too be. Thanks for all your videos man. A fan from Winnipeg Canada!
That happened to you in Canada? That wont do. Go to your local IBEW and ask about apprenticeships, you may have to do a foundation's course but in Canada getting an apprenticeship should be basically done for you. Talk to whatever school near you hosts trades programs, your local IBEW or start phoning every electrical company in the city. Good luck!
I'm a first year apprentice and every time I'm introduced to something new that's a little complicated, the master electrician I'm working under always explains how it works and what it does like shit. So when I get home I just watch you to see what the hell he was talking about.
