 Plugging with a zero speed switch. What plugging is is basically stopping a motor abruptly or quite suddenly And it is done by throwing it into reverse as soon as you hit the stop button It'd be like driving down a highway at a hundred kilometers an hour and throwing it into reverse it would stop your car very quickly and You need to make sure that your motor itself could actually handle that So what we're going to do is look at the zero speed switch and how it is used to plug a circuit What we have here is your basic start stop up here, but you notice that we're using like a forward and reverse We've got our interlocks here. We've got our Electrical interlocks here, and then we have this funny looking thing at the bottom here This is our zero speed switch which works on centrifugal force when the motor is going forward It's going to throw this switch up into this position if the motor is suddenly gone into the reverse It's going to throw it down into this position. So that's why we have this arrow It's showing that there's centrifugal motion with the switch itself So let's go ahead and we're going to hit the start button and see what happens As we hit start so start we push down power can now get through there's a normally closed interlock there But it can get through because it's closed Energizes F goes through the overloads this coil stays energized or becomes energized Pulls in the F contacts down here, which are physically attached This coil controls these contacts and when I let go of this start button It will hold in and keep running What will also happen is this motor that this coil is controlling will start moving forward and when that happens It's going to throw this centrifugal switch into the forward motion So we let go of this it's being held in F coil The motor starts to spin as the motor starts to spin the zero speed switch Which is attached to the shaft will move into this position here It can't deenergize this R won't energize because if this coil here F is Is energized this F contact closes But what we had before too was this F contact down here this opens This was a normally closed contact that is now open as long as this is energized This is open which will happen is this goes through but it can't get across because it is open So it won't energize F and R at the same time Now we're going to experience some magic of the zero speed switch. We're going to hit stop stop deenergizes F That will shut down this part of the circuit When F deenergizes this opened but this closed and if the motor is still spinning in the forward direction Still going around and around around because it might have some sort of centrifugal force causing it to go This zero speed switch is still in the forward position. We want that to stop So what'll happen now is power can come through the zero speed switch go through the normally closed contact Which is closed now and energize the reverse So this was moving forward and suddenly we have thrown it into reverse when that happens This zero speed switch feels that it's now going in the reverse direction It's going from this forward position down to the reverse position When that happens power no longer can get across because it can get down to this point here But it no longer goes to the R because it's an open circuit at this point this deenergizes the R and What will happen is it will stop going in reverse and this will end up back into its original position and The motor is completely stopped and the centrifugal switch is now in its Normal position sitting between the forward and the reverse and so that is how you use a zero speed switch Which is attached to the shaft of the motor to plug a motor to stop