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Does anyone know anything about reversible induction motors? Answered

 I have a squirrel cage motor from a tumble drier and don't want to wire it up wrong!  I studied the timer switch and it looks as though there is a main power wire which is on most of the time, and this would periodically disconnect and another wire would briefly be connected instead.  I assume this reverses the direction.  I haven't switched the motor on yet, but if it turns out that it starts in a random direction, is there a way to guarantee it will always go one way?



I have a belief that the third wire is part of a starting circuit, you can read more here for one.
These things are designed to rotate in the one direction though.


Many thanks for the response.  Both windings are connected to an 8uF capacitor - I think it's just one capacitor between them, but it could be 2 capacitors with a common earth.  The extra winding gets it's power through a 2.5 ohm resistor, so this would provide the required phase shift.  I had assumed it must be a direction changing winding because of it coming from a tumble drier, but having never actually seen it in operation I don't know, so I will go with your belief (so the timer must just have provided a pause in the rotation).  Gives me a much nicer circuit to work with anyway :-D


I see not much need for a tumble-dryer to change direction, but wouldn't except that your machine does. I had an old AC motor years ago, which featured a centrifugal-switch, when it got up to speed the switch cut - out, that was a starter circuit which operated for a second or two.
If you have a reverse need, I'd look to a mechanical reverse rather than an electrical one.


I just thought they did that - I think I got that idea from the ones you find in laundrettes.  Anyways, I'm glad it's for starting the motor and not making it change direction.

Many thanks,