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Product Single phase motor direction

Product

jcdammeyer

John
Premium Member
A friend had a 220VAC single phase hobart fridge motor rewound here in Victoria. Capacitor start. I have no knowledge past that as far as wires etc. but apparently it runs in the wrong direction.
Single phase AC motors are outside my knowledge level but I'm guessing one of the windings is connected backwards? Or perhaps the rewind place rewound it counter clockwise instead of clockwise?
How does one change the direction of a single phase motor?
John

Edit: I did find this. Does it make sense?
 
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jcdammeyer

John
Premium Member
Here's the wiring from my milling machine. The motor has essentially 3 wires and the Revers/Stop/Forward switch shuffles where the AC goes. But if only two wires come out of the motor, wired for only one direction, then one has to dig deeper to find out how to reverse it. This diagram doesn't show that.

1685128641804.png
 

Tom Kitta

Ultra Member
Essentially you need multiple wires coming in out of your 1ph motor to be able to reverse it. Reversing is done by switching two wires around.

If this was not provided by rewinding place the motor is wired for only one direction.

Note when specifying direction of rotation there are two methods - looking from the front or back of the motor. It has to be stated very clearly which direction you want - sometimes there is even an arrow sticker on the motor showing direction of spin.
 

Dabbler

ersatz engineer
Edit: I did find this. Does it make sense?
That is the best description of reversing single phase motors I've seen. Thanks!

-- the only thing he didn't cover is a so-called "universal motor, often used in small fans or tiny gear trains. They reverse by removing the rotor and putting it in the other way.
 

phaxtris

(Ryan)
Premium Member
Premium Member
assuming you have a reversible motor the starter winding just give the motor a "kick" in one direction or the other depending on how you have the starter winding wired

if you actually wire the main coil in a starter coil wound motor without the starter coil wired in, it will not move unless you give the shaft a nudge, then the motor will spin which ever direction you spun the shaft

everything hinges on a the wiring of the starter windings, and weather or not you have access to change the polarity of those wires, if you can either the motor will have 4 or 5 wires coming out of it, possibly going into what looks like a coil cover, or there will be a small removeable access cover on the back side of the motor. Not all motors give you access to the starter coil wiring.
 

Brian H

Super User
This is of an interest to me. I had thought about how to be able to reverse the motor (1ph 220v) on my PDM-30. King said it could not be done...

This again falls into my lack of knowledge on electronic stuff....although I did manage to successfully wire a reversing switch on my mini-mill DC motor
 

slow-poke

Ultra Member
I recently reversed a "non reversible" 2 wire motor. The reversible ones bring out all the wires to allow the user to connect as required. I pulled the end with the starter switch, figured out what wires were for the start winding and reversed them, IIRC needed to cut and solder one connection and use a bit of heatshrink. Took about 20 minutes.
 

jcdammeyer

John
Premium Member
A quick update on my friends motor. After he took it apart and sketched up a drawing he found the electrician who installed it left one lead of the motor (likely the starter winding) not connected. He also discovered that the centrifugal switch was damaged and didn't work. So the motor started in whatever direction was comfortable for it.
The starter winding is connected internally to one side of the main winding so even though there are 4 wires coming out of the rewinding two of them are connected together. But until a new centrifugal switch is installed it's hard to say if the internal connection is on the correct side of the main winding for the desired motor direction.
Thanks everyone for the comments and links. They were very helpful and made it possible for me to guide my friend over the phone.
 
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