Basic Motor Control: 3 wire Start Stop Circuit

hey everybody this is Walter with Access electric and today I wanted to go over a three-wire start/stop circuit now this is the foundation of all motor control if you can understand this it'll give you a good foundation to build upon all motor control is based on this simple circuit now I've worked for a long time in electrical field and I've worked with a lot of electricians and some guys are good electricians but they get afraid of motor control they're intimidated by it yet they could do a residential 3-way 4-way switch without even thinking about it but when it comes to motor control they're scared what I want to do for you is to show you there's nothing to be intimidated about this is all basically the same thing it's all about switching if you're using switching to control what you want the circuit to do how you want the circuit to close how you want that motor to be controlled on and off that's it everything else is just an add-on to that later you can install timers you can install multiple start stops you can install all kinds of new controls but without this foundation it's going to be really difficult for you so today let's get it right into three wire start/stop motor control [Music] so let me show you a three-wire start/stop this is a board I put together and it's a plexiglass board and here you have a starter a motor control starter and overload this is a breaker just to control our control power and then you have the start button and the stop button that's basically and you have three wires to the start/stop and that will get right into how this works but I just want to show you just want to go through this you turn on the start button the contactor closes it stays closed until you push the stop button if the stop button is pressed it will not start it'll only start if the stop button is not pressed start stop this is a really simple circuit I want to move to the computer I'm going to show you on the screen exactly what this circuit is doing and then we'll come back to this display hey everybody we're back here and we're at my computer and here on the screen I'm showing you a three-wire start/stop circuit now this all originates from this bucket this is a starter bucket this rectangle right here represents a starter bucket and here we have a 40 volt power source through a main breaker which then feeds the top side of a contactor okay this contactor has four normally open contacts and it's all controlled by this coil when this coil is energized all four of these contacts close these three contacts this this is line 1 line 2 and line 3 these three contacts feed this motor they feed current to this motor when they close this motor is energized this contact is our holding control contact and for that to work we have a second power source now sometimes this is accomplished with a transformer and sometimes it's control it's accomplished with an outside control power here we're showing it outside 120-volt control power source so we have our neutral wire coming down through our overload circuit to our coil our overload circuit is controlled by the three heaters these are three thermal switches in the starter in the overload bank of the starter and what happens is when they get hot if the motor is drawing more current than it should these will get hot and this normally closed switch you can see it's closed right now will open when it opens the coil will lose its neutral and then we have our power going out to our stop button our stop button feeding are normally open control holding contact it's also feeding our Start button and then we have our Start circuit coming from our Start button back to the coil of the starter now let me energize this circuit so you can see what's going on alright so here we have power turned on here we have our fuses open so nothing no power is going to the switches right now our neutral is going all the way through the coil but nothing else is happening so let's turn on our 480 volt power to our starter and it's going down to the contacts of the starter but it's not going to the motor because they're our contacts are currently open nothing will happen if I came over here hit the start start button or hit the stop button nothing happens because there's no power there's our control powers turned off and if you notice the start button is a momentary as long as I'm pushing the button the button is closed the stop button exact is exactly the opposite as long as I'm pushing the button the button is open this button is called a normally closed button this button is called a normally open button okay so let's turn on our control power our control power is now on power is energized 110 volts is energized through the normally closed stop button and that button is feeding our start button and feeding our holding contact now if I push the stop button we will lose power going through the stop button but as soon as I let go power is reestablished to our contact to our contact and to our Start button now this motor will not start until we press start when I do press start all these this coil will be energized all these contacts will be closed and when it closes this circuit will bypass our Start button right here so let's close its hit start okay I'll let go the coil has remained energized because as soon as I hit start this contact closed which keeps itself on it bypassed the start button so I can come over and I can press the start button all I want nothing will happen it's going to stay running until I hit stop once I hit stop now I'm gonna have to hit start to get this to work again there you go it's running so there's only two things that can stop this circuit if I lose power actually three things if I lose power in our control circuit it'll stop if I hit the stop button it'll stop and if the overloads trip on this starter it will stop the overload tripped this overload circuit opened I lost my neutral to the coil which caused the coil to de-energize which opened all the context the motor stopped as well as the control circuit stopped so now I can try to hit start and it will not start instead until I reset my overloads now i've reestablished my neutral connection I can start the motor will stay energized now this is what it looks like in the field this is how you wire it and I wanted to show it to you this way because I wanted you to see the bucket and I wanted you to see the three wires that are leaving the bucket going out to the field feeding the start/stop button and controlling the starter I'm going to show you what this looks like in a in a ladder diagram but most people get up on especially electric when an electricians first learning this and they get hung up on this is when you look at it in a wire diagram this coil this contact right here they don't seem to know what to do with that because it's confusing in a ladder diagram let me let me show you what that looks like let's turn the power back on we're gonna go down to a ladder diagram of the exact same circuit this is the exact same circuit we just looked at you have 110 volts over here you have a neutral the 110 volts is feeding the stop button power is going through the normally closed stop button to the start button and here's what I'm talking about it also it feeds a start button but it also feeds the motor starters auxilary contact which is normally open and then it comes back both from both places from the start button and from the auxilary contact and feeds the coil when you hit start the motor coil energizes the motor contacts close this auxilary closes which keeps itself on and you've you've effectively bypassed the start button keeping itself on and it'll stay on until you either hit stop or you lose an overload if the overload opens the neutral will be lost which will de energize a circuit which will open the contact and it'll cause you to have to reset the overload and come back and hit the start button again really folks that's it for 3 wire starts up that's how it works it's really not as complicated as some people make it out to be it's really really simple now if you want to excel at these things start thinking about what would it what would how would you have to wire here ah let me move down to this ladder how would you have to wire that ladder if you had to stop buttons if you had three stop buttons and three start buttons how would that ladder have to look to accomplish that control circuit after that you can add timers you can add horns to the circuit you can add indicator lights to the circuit all kinds of things but this is the bay three wires start/stop that all motor control is based on so if you liked this video and you want to see more videos like this leave it just leave a comment in the comments below I'll be happy to demonstrate some other circuits that you're more interested in and we'll go over those make new videos about those so if you like this video hit subscribe if you like it you want to see more like it click the like button and in the Bell to be notified of more videos like this and until next time have a good day [Music] you

Channel: AccessToPower

Views: 165,364

Rating: 4.9553785 out of 5

Keywords: accesstopower, electrical contractor, electrical training, Access Electric, Start/Stop, 3 wire Start/Stop, Start Stop, Start Stop Circuit, motor control, motor starter, motor, contactor, starter, contactor wiring, three wire start stop, motor protection, motor control simulation, Ladder Diagram, Electrical Schematic, Schematic, Relay Logic, Electrical Drawing, Electrical Simulation, motor wiring, contactor wiring diagram, electrical wiring, how does a 3 wire controller work

Id: 6ujtUToPiZs

Length: 11min 11sec (671 seconds)

Published: Wed Aug 01 2018