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How to Slow Down a 240Vac Electric Motor? Answered

I bought a small, industrial motor and want to safely slow it's rpm. 
Does anyone have any advice as how to best go about this? 
I've looked into gearing and found this to be quite complex but understand that an alternative option may be to change the voltage received by the motor? 

Thank you for any help you provide


You have only really 2 options for that motor. Gear it down, or use a speed controller. Silicon chip magazine did a kit for a speed controller last year, if you want to build it yourself. You cant just just use any speed controller for that type of motor. Yours is and induction motor so you have to control the frequency of the AC . A universal motor has brushes inside it and can be controlled by changing the voltage, and the speed controller for that type of motor is much cheaper.



From what's there it is a motor that requires a capacitor to run, next to impossible to slow these down.
If it starts and runs without a capacitor you can tr a dimmer that can handle inductiv loads - if you are lucky you find one at Bunnings but lately I saw only "fan controllers" which are useless.
You can always run them with a frequency motor converter but they mostly come for three pahse motors to connect them to single phase use with speed and break control.

Might be better to salvage an old treadmill to get a strong motor with speed control here in AU...

Change the AC frequency.

AC motors work by the AC current changing the magnetic pols in your case 50 cycles if you change that to 40 cycles the pols change slower and the motor turns slower. Just watch the current if the current stays the same you are OK, if the current goes up the motor will burn out. The only other way is a current limiting circuit but that is load regulated.

Reducing the voltage going into your motor should slow it down, however. An AC motor may not like that, some go bad, some will shut off, but some do work fine, so reduce voltage at your own risk :)

If you still wish to decrease the voltage you'll need a potentiometer of some sort, make sure it's rated to the voltage that it will be receiving, a good quick DIY potentiometer might be a dimmable light switch, but again, make sure it can handle the voltage. A quick google search will give you a far better tutorial on how to hook one up then I can.

Hope this helps!