Exhaust Fan Wiring

[michaeltrego]

I have this exhaust fan from a microwave and it has an 8-pin plug. How would it be wired to a dimmer switch or potentiometer?

 

[Owly055]

It can't be.........It's an induction motor..... that much is obvious from the schematic. (which is clear as mud)

H.W.

 

[michaeltrego]

It can't be.........It's an induction motor..... that much is obvious from the schematic. (which is clear as mud)

H.W.

Do you mean it can't be wired for variable speed? What about simple on/off?

 

[Owly055]

Do you mean it can't be wired for variable speed? What about simple on/off?

It is designed to be wired for multi speed............. not variable speed. Only brush motors can be operated on a rheostat. Induction motors do not work on a rheostat. If you look at the diagram........ which really isn't a proper wiring diagram, you will note that Blue, Violet, and Yellow are High, Medium, and Low..... Brown is labeled B.... I don't know what that stands for. It may be another speed. White should be neutral, and appears from the drawing that the hot wire switches between these for for the different speeds.

Try bench testing it at home with a cord. Connect the white to neutral, and each of those 4 colors in turn to the hot wire. Use wire nuts on all wires when testing. Just take an old appliance cord and strip the ends. Connect it in one configuration, and plug it in momentarily..... Repeat with each configuration. It should give you 4 speeds. You can then buy a rotary switch and connect it to allow you to select the speeds you want.

Don't be afraid to test......... I've done countless motors this way..... hold the plug, and just poke it in the outlet briefly.... If it doesn't sound right, jerk it right out again, you won't hurt anything.

You MUST have the run capacitor........... This will be a little metal case oil filled run capacitor. It may be round, or it may be oblong. Run capacitors are different from start capacitors (the black plastic ones). Grainger's will have the cap you need.


H.W.

 

[fbold1]

looks like the yellow would be 120v and the white common. you also need the capacitor hooked up to run.

 

[wilserbrewer]

I would think for a brewing operation you will most likely only need the "high" or 100% power setting. I would not bother trying to use it with variable speed settings.

 

[michaeltrego]

Thanks everyone - I'll pick up a 10uF run capacitor and give it a test as suggested. Thanks again!

 

[Mike Misko]

I have another question about this fan. Can a reostat be connected to only one of the Speed wires., either the high or lo speed or will it cause damage to the motor. The thing is , for my purpose the lo speed is still to high and I need to slow it down a bit. Thx all

 

[michaeltrego]

View attachment 656585
I have another question about this fan. Can a reostat be connected to only one of the Speed wires., either the high or lo speed or will it cause damage to the motor. The thing is , for my purpose the lo speed is still to high and I need to slow it down a bit. Thx all

I used a TEMCo Run Capacitor RC0050-10 uf and wired it to a three-speed switch, which works great. The low speed is fine for general exhaust and the high speed cranks when the boil is underway.

 

[Mike Misko]

I also have a 10 uf connected but again the low is still faster than I want. Will a reostat reduce the speed without any harmful effects on the motor.