How to manage 120v AC motor

As a novice, I am unfortunate enough to have a need to manage a Dayton motor [120V 60Hz @ 1.16A] (model#: 4M073D).

I have a Mega, Duemilanove, and 4 Nano boards and a Motor Shield from Ladyada.com --- hoping not to fry too many of them ;). I have to be able to control motor speed (fast/slow) and rotation (forward/backward).

I have done my homework and have read various ways to attack this problem in different applications, but I couldn't find any that were conclusive enough (given my adolescence in the field) to apply to my situation.

I know all the warnings and dangers of working with 120VAC.

So my question is -- Does anyone have a simple schematic perhaps with a little explanation of how this would be set up using Arduino?

Thanks.

//Clint

I should start by saying, I am fairly ignorant of mains AC motors. Others are likely much better than me.

It looks like an induction motor, and I think induction motors are synchronous, so I assume it requires a variable frequency power supply.

Have you found a good article that I could read about the theory? I might be able to help.

GB
[edit]Tidied up my English[/edit]

Well I think you will need to tells more about what you mean to "manage" the motor. Do you need to just be able to turn it on and off via the Arduino? If so a solid-state relay should work. How do you plan to power the motor? With household 120vac?

Lefty

Well I think you will need to tells more about what you mean to "manage" the motor. Do you need to just be able to turn it on and off via the Arduino? If so a solid-state relay should work. How do you plan to power the motor? With household 120vac?

By "manage", I mean what I stated in the original post:
"I have to be able to control motor speed (fast/slow) and rotation (forward/backward)".

I'm not quite sure why your asking what would power the motor.. the motor requires 120VAC which is why I posted this question in the first place. I'm hoping to power Arduino/Shields by scraping a little off the 120; otherwise I'll just add a 9VDC or something for it.

This is a regular 3 prong 120vac you would find in a house or outdoor patio.

//Clint

Can you explain what you understand to be the right way to control speed and direction?

I still think it is a synchronous motor, and moves at a speed determined by the frequency of the AC supply voltage. Do you think this too?

If that is true, do you think a 120V AC power source, with variable frequency is needed for variable speed?

GB

As a novice, I am unfortunate enough to have a need to manage a Dayton motor [120V 60Hz @ 1.16A] (model#: 4M073D).

From what I can see (looking up that dayton part number), that is a c-frame shaded-pole induction motor; you can't change the direction of such a motor, it spins in one direction only (toward the shaded pole):

You can vary their speed, though - as the wikipedia article states - with a TRIAC control.

Hope this helps...

:slight_smile:

Induction motors have huge turn-on current spikes, note, so you'll have to rate any relay or triac very conservatively. In general induction motors are inflexible and hard to control. They are for turning constant load at constant speed really.

I googled for "shaded-pole motor speed control" and got this Controlling a Shaded Pole AC Induction Motor

Summary,

Voltage/Frequency = Constant
For example

Veff = 266V F=60Hz n=1200 rpm
Veff = 220V F=50Hz n=1000 rpm (Normal condition)
Veff = 176V F=40Hz n= 800 rpm

... also have limited useful speed range

HTH
GB

Thanks for the educational feedback everyone.

I still would like to know how (in general) I would connect a 120VAC device using Arduino (and shield?).

Thanks again for all your help!

//Clint

Clint - I haven't done AC switching from an Arduino.

If I were to do it, I would use isolation, specifically an opto-coupler, which uses light to seperate the Arduino from the mains power.

I found this article which explains this stuff in more detail,
http://www.sullivan-county.com/ele/triacs.htm
including a way to use an Arduino to control mains AC:
http://www.sullivan-county.com/ele/arduino_power_control.htm

HTH
GB