Wiring a Random Induction Motor

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Wiring a Random Induction Motor

Have you ever found a motor that has been discarded that is associated with a piece of equipment, but all you wanted was the motor? Well that is what happened to me when I found this shredder in the dumpster. The problem with the shredder was that the gearing was seized, which is why I assume it was discarded. I may deal with that issue later but for now, I will focus on the motor. There is a “brain” associated with the motor and the shredder pieces/parts that is hindering me and is not needed for my uses. So I will try to figure out how to bypass that and get the motor running as I require.

Supplies

Hand or Power tools
Electric couplings, wire nuts, etc.
multimeter
Power source
Safety gear

Troubleshooting the Motor and It's Connections

This shredder has sensors and switches that are all associated with the shredding mechanism in order to run forward and reverse. Going forward all I can imagine is wanting a shredder to shred, nothing fancy. So my plan is to get rid of the brain and simply have a power switch and it’s capacitor for the start winding to run the motor to shred. However in order to do that, I need to figure out which winding is the start winding so that I can run it straight to the capacitor and bypass everything else in order for the motor to run and stay running.

For induction motors, they are usually single phase AC motors that plug into residential house power. Just for reference, I live in the USA, so take that for what it’s worth. You can also usually tell that they are AC induction motors because they have a capacitor. The capacitor acts momentarily as an “additional phase” to get the motor running. In fact, if you plug the motor in and start it and all you hear is a hum but the motor doesn’t spin, it usually means that the capacitor junk and may need to be replaced. That, or the capacitor was wired incorrectly. So now that you have some background, let’s get rolling (pun intended)!

On picture 2, I arbitrarily label the three leads as T, M, B, for top, middle, and bottom. I use my multimeter and run the ohms setting across M & T, T & B, and M & B.
Looking at picture 3 you’ll see that MB & BT are both 4 ohms while MT is 6 ohms. The higher resistance leads me to believe that the top and middle connections are associated with the start winding. Therefore, they need to be wired to the capacitor. I also need to run the motor with the capacitor to the switch and to the power cord, which can all be seen in the video and picture 3.

The wiring diagram I have labeled is arbitrary with things like B1 and R to mean black wire one and red wire and really holds no more significance than that. It was just my way to keep my head and methods straight.

Re-wiring to Fit Our Needs

Once I have the brain, the switches, and optical sensor wiring removed, I was able to hook the motor up to power along with its capacitor according to my hypothesized schematic. If you are testing, I do not recommend wiring it up as I have in my pictures, since they are not very electrically safe and I’m sure the electricians out there are cringing at this. But, I assure you I did have a healthy uneasiness with what I was doing and maintained safety.
I mean, I wouldn’t be writing this instructable if I got shocked. Right?

Joking aside, be safe!

My test was simply to start the motor via it’s switch once it was connected to power. And voila, it ran. That being said, it ran in the forward direction but not reverse. When I tried throwing the switch in reverse it did nothing, but I really don’t care as that was not my intention anyway.

Hopefully this help guide you for motor wiring and if you have the opportunity to give new life to machinery, I implore you to do so. I don't particularly like throw away culture and heck, If I can get a motor for free with a little work, then so be it!!