What's going on my friends? This is Dustin Stelzer with Electrician U,
and today we're gonna talk about the difference between a relay and a contactor.
So relays and contactors are pretty much the same thing. I mean, they essentially work
the same way. Both of them are electromagnetic switches. So, rather than you having to come up
and push to turn this device on, you know like manually, you can actually send current to it,
send an electrical signal, and that is what turns the thing on. It does that for both of these. Both
of them are electromagnetic switches. Both of them are really used as like multi pull switches. So,
if you want to control several different circuits, or several different loads that are on different
circuits at the same time, you can do that with both of these, whereas a normal light
switch you can only control one thing. Both of them have coils. So, there's actually a
coil of wire in here that when you send current through it, it engages an electromagnet and it
sucks the contact shut or opens them up. They both operate that way, and both of them have contacts,
so they have multiple different contacts that you can run - say home runs from a panel to,
and then you run out of the other contacts out to the field somewhere to different kinds of
things. Relays also have them. So even though they're very similar in a lot of ways ,they're
very different in some important ways. Typically a relay is going to be a low voltage or low current
application meaning that both the coil and the contacts really can't handle a lot of current.
A lot of these things are rated at like 5 amps 10 amps 15 amps, where contactors are typically used
in higher voltage, higher current environments. The contacts on these can handle anywhere from 30,
40, 50 amps. The metal and the pieces that make up the inside of this relay are actually
a lot smaller and more compact, whereas a contactor everything is a lot more beefy.
Typically with relays you cannot change the coils inside of them. Whatever rating you
get this device is the rating you got to run to it and through it, whereas a lot of contactors,
not all of them but a lot of them, you can actually take this coil pack out and put a
brand new coil in it. So if you have a 120 volt coil but you need a 277 coil, a lot of times you
can just go to the supply house, pull this out, put a new one in. Another difference is that
relays can typically only control up to like two or three loads. They're just designed for a couple
of different functions, whereas contactors this one specifically can do four loads,
and there's some even like this crazy one back here that's a 6 pole, and it can even be expanded
to do 8 or this guy up here can do 12. So, they're a lot more expansive. Most relays also have both
a normally open and a normally closed option, so you can kind of turn some things off while turning
other things on at the same time with a relay - where most general use contactors you can't do
that. General use contactors are typically only normally open or normally closed, so everything
is going to turn on, or everything is going to turn off when you energize that coil. However,
lighting contactors like again this guy, or this guy you can change and you can add auxiliaries to
them. You can kind of move back and forth whether or not some of them are normally
open and some of them are normally closed, so they have a little bit more high functionality,
but again it's kind of the same thing it's just limited to usually two or three things
or anywhere from like two to twelve in that case. Another thing that some contactors have,
again lighting contactors more specifically, is they have the ability to be mechanically held.
So you can latch them in place, and that way if power is gone or you lose power to the coil all
the lights fail in an on position, where relays don't have that function. Basically once you
send power to them and you take power away they turn on or they turn off like a general purpose
contactor would. So that's pretty much it for the differences between contactors and relays. I
hope that kind of cleared some things up. A lot of people when they hear relay they're like, "What is
that? It's some like magical switch..." No. It's the same thing they're both just electromagnetic
switches. You send power to them to turn them on and off, and that's as difficult as it gets. So,
I'm gonna have a video that's gonna come out, specifically on relays that just talks about how
all relays work, and I'm going to cover a bunch of different types. I'm gonna have another video that
just covers contactors - how they work. I'm gonna tear them open so you can see the insides of them,
talk about different environments in which you use them, and then I'm also going to
do a video on both of these where I'm gonna wire each one of them, and draw some diagrams,
and show you how they work, and how the practical application of both of these works out. So in the
next couple of months, you're going to see a few different videos on contactors and relays.
So thank you guys so much! Really appreciate your attention, and I will see you in the next episode!