[Documentation] Revised: Hacking an AC motor with Arduino

* updates:    The instructables is online now by our very own Marcela Godoy :

 http://www.instructables.com/id/How-to-hack-an-Electric-Hoist-AC-motor/

We were hired to do a small hacking project for a trade show.   Basically we want to be able to control the direction of the AC motor and to launch timed actions. 

The AC motor that we’re giving has a built-in motor controller, a capacitor, and a pendent switch, that allows manually adjusting the directions.   

We are able to control the direction of an AC motor from arduino uno,  and still allow any manual control from the pendent switch (when arduino is not running).

We figured out a few things in this project which will probably be helpful to point out for anyone who attempt to do so on one’s own:    

1. The wiring of the motor controller and its switch. 

2.  The circuit for interfacing AC motor with 5V logic using Solid State Relays and an Arduino Uno. The Arduino control it in both direction using two PWM output.  

3.  When we control the AC motors with the solid state relays, the relays dont discharged the capacitor.  So when the capacitor is not being discharged, the motor will go on the same direction as the charge. The inclusion of a resistor between the both terminals of the capacitor will help discharging the capacitor when the motor is not operating.  

This is a place holder for a video of the operation when we set it up at the space tomorrow.

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Materials you’ll need:

  •  http://www.harborfreight.com/1100-lb-capacity-electric-hoist-93251.html   // datasheet can be found here.  We started with 880 lb capacity and end up using 1100 lb.  The only difference in this circuit is the value of the resistors
  • Amico 250V 25A SSR-25DA Temperature Control Solid State Relay. We need 4 units.
  •  200K ohm resistor, you’ll need one for each capacitor
  • 14 AWG cable to handle AC current
  • Arduino Uno
  • small breadboard

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A.  Wiring the Solid State Relay from Pendent switch

Diagram:

A-1  
Our wiring looks like this:

B.  The Charge will start at its maximum value which is 200K with this capacitor. We  add a 200K Ohm Resistor on both leads of the Capacitor. There are two capacitors in parallel for the 1100 lb motor. So the resistors are  hook up in parallel in this image. 

tumblr_inline_mgsr096Bdz1rd06m5.jpg
* Notes:   To calculate the discharge time.  We have 80 uf capacitors and we are discharging with a 200k resistor  The time constant is 16 seconds.  T=R * C  Where, R is in Ω’s and C in Farads.

* Notes:   To calculate the discharge time.  We have 80 uf capacitors and we are discharging with a 200k resistor  The time constant is 16 seconds.  T=R * C  Where, R is in Ω’s and C in Farads.

D.  Happy Hacking

D. 

Happy Hacking

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C.  Try this code for your arduino to control the direction with a 25% duty cycle

You can download the code from github

https://github.com/openMolmol/hack-acmotor-with-relay-and-arduino

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