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Dryer motor Answered

Alright folks, after my last posting of the washing machine motor failed to prove helpful, ( because of my lack of understanding, not the help offered, that was excellent ) I decided to scrap that idea and start anew, this time with a dryer motor. I have a motor here now that like before I simply want to be able to start and stop at will. This time around I have the original wiring diagram too! So, my question is how do I wire the thing, simply with an on/off switch? No variable speeds, no reverse directions, just on/off. Oh, and Id like it run on 110v as well.


I have a centrifugally switched 240v dryer motor. I have two wires coming from the wall. And three wires coming out of the motor. There is also the centrifugal switch attached to the motor. To get the motor to work at all, I connect either the red or yellow wires coming out of the motor to the hot wire from the wall, and the blue wire attached to the neutral. If I turn the motor on at this point, it will buzz/hum loudly at me without actually turning. After giving it a small spin in either direction, it will spin up and run normally. I was thinking that the unused yellow or red wire probably had a similar voltage to the wall on it due to the design of the motor. (the unused wire would act as a generator.) I successfully managed to run some lights by connecting them between the neutral and the unused wire. But if I left them connected and started up the motor it would spin up without my assistance. So by connecting the light (150w halogen (convenient test as it's not concerned about low voltages) to the normally closed side of the switch, it will act as a load and spin up the motor until the centrifugal switch cuts in and turns off the light. So the light will come on for about 1 second and cut out.


8 years ago

Suppose I can't see the original colours of the three wires come out of the burnt dryer motor just say brown (Brn, black (Blk), and blue (Blu) and the specs of the capacitor; I found used motor with wires in different  colours from the "original" say white (Wht), green (Grn), red (Red).  If the resistances between Wht and Grn  57 Ohms, Wht-Red   24 Ohms, Red-Grn 80 Ohms (all are approximates; with simple AVO-meter), what is the right size of the capacitor? Which wires for the capacitor ?    Which wires are to electric line? I used to wire as told by the scrap motor supplier, which sometime ended in only few days of the motor services.

This will get you going if I haven't missed something. There are wires coming out of the motor connection box that are used to shut down when different drying times are selected on the timer, they can be cut from branched connectors in the box. make sure the other branch connects to the motor winding with good electrical contact. PURPLE, BLUE, RED, (RED & BLACK) Can be removed. Don't cut Capacitor Wires WHITE & RED. Would like to know if this helped.


is this box below the motor automatic start switch ? if its just a contactor than what switches it (disconnects the capacitor) after few seconds ? can the capacitor be left connected all the time ? (in all appliances i know (240 V 1 ph) it is)

The Capacitor disconnects by way of an electrical switch inside the motor housing, it is operated by spinning weights on the armature. I did not show this in my reply because this should be a built in already connected. pin #2 supplies the power to the internal switch as well as the run winding coils, the Said switch powers the starting winding through the Capacitor.

is that contactor (under the motor in the drawing) actually built into the motor ? why are it and the motor drawn separately in the scheme then ?

Yes it is. This is electrical Drawing, There seems to be Taboo on showing any mechanical parts , The switch is a mechanical device and only the contacts are noted. another pic. for you.


that makes it clear thanks :) but i still dont get it completely there should be more wires coming from the motor ? (extra 2 for the switch). they should go then between the motor and the box but they are missing in the drawing in the photo above. the drawing also makes clear to me that the switch is not just there in series with the start coil inside and are those motors really different from the 240 V motors i know ? if yes then why ? th motors i know dont have any switch like that. i opened few motors up to 1 ph 200 W and one 1 ph 1500 W. in all the wires are hard wired to the coils. the rotor is not connected to anything - no brushes etc. there is nothing that can act as or control a switch other stuff that shows that the capacitor is connected all the time - if you disconnect the capacitor when its running it stops and goes zzzzz. you can change the direction in some motors if you move the capacitor to the other coil. that would be impossible with switched motors cause it would switch off the now main coil when it reaches high enough speed

quick somewhat relavent question that i think i asked before but I can't remember the answer. can one pwm an AC motor that has a start cap without like killing the capacitor (most are only rated at like 20 starts an hour)

11010010110 says, a light dimmer is similar to pwm but it cuts the existing wave of 50 / 60 HZ ac. This would be my answer also. or cuts a portion of the wave. Pulse width is generally associated with DC. current, a controlled measure of time, ON -OFF switch. An example, The fuel system on automobiles uses pulse width for fuel injection, Pedal to the metal the fuel injector valve (solenoid ) remains open a long time when compared to idle because of the air fuel ratio volume.

i know from our 240 V motors (that have the capacitor connected all the time) that its possible down to a certain speed (and not lower)

i tinkered with this fan and the controller that comes with it

inside the controller there is a circuit identical to a standard light dimmer. its limited to some minimum and cannot be turned to 0 though. i guess that if you let it go below some speed it'll stop and go overheating

the direction is changed by switching the capacitor from 1 coil to another

in motors that use the capacitor for short periods it may be more of issue. but i think that above some minimum speed there won't be problem

a light dimmer is similar to pwm but it cuts the existing wave of 50 / 60 HZ ac and does not work at high frequency

Wired according to Yeasayer's diagram up there. It makes a buzzing noise, but does not turn. I found some numbers on the contacter (?) which is screwed onto the motor itself but is removeable. they are NORGE 63-4210 3ASM9D9B8

disconnect the motor from the contactor / start switch connect it and the capacitor to mains like here see if it works and disconnect after 10 - 20 sec so the capacitor and the start coil won't overheat


That diagram pictured above is on the inside of the dryer itself, what you see is what I see, although what I see looks like a complex etch a sketch drawing hehe.

can you see whats inside the start switch ? (the box with numbers below the motor) or does it have serial etc that can be searched in inet ? your motor has the capacitor connected only at startup and disconnected later. it may require this (and not accept leaving the capacitor connected like in the 240 V motors which i know). we need then to figure out what controls the connecting and disconnecting of the capacitor

This is all starting to get complicated. If the cap has to be on to start then turns off, can I not just wire a switch in the cap wire? basically have one switch for the main power and 1 for the cap?

the machine allready makes this automatically all whats needed is to find which part of it controls that it may be for example a signal from the main program timer (unlikely) a thermal switch inside the box with the numbers a thermal or mechanical switch inside the motor itself its also not clear to me if the box is built in to the motor or a separate component and the motor only has 3 wires yeasayer can probably help you more here. i am familiar only with motors that need the capacitor all the time (they stop and zzzz if you disconnect it when its working)

I had this exact same problem with the washing machine motor. Buzzed but thats all. If the cap is controlled externally then perhaps one wire or the other should be attached to a different switch. Gonna try some different things and see what it gets me. Hopefully not killed.

Success! Yeasayer's diagram was right, I inadvertently disconnected a cap wire by mistake. Thanks folks for all the help. Im going to see if I can get the motor from the washer to work correctly now.

Thanks gonna try that asap. Can I just wire it for 110v this way?

Yes, Most Drier motors are 110 Volt, the 220 V, is used for the heating elements only. Note; If the motor Makes a loud buzzing noise but does not start or turns' very slow this could indicate a failed starting capacitor or a faulty connection. Always discharge a capacitor by temporarally shorting the terminals with an insulated Screwdriver before handling

How many wires does it have and what colour are they? ?

Offhand, I dont know. The diagram has them all listed. Looks like 7 here on the pic.

sorry for the double post, but can you guys see the image bigger by clicking on the little I in the corner or is that a poster function?


9 years ago

Yeah, Im gonna need precise instructions to get it up and running I think.

I think all you need is the start cap, but I don't know how it goes via that diagram, it seems more complicated then it had to be >.