Single Phase Motor Direction
Single Phase Motor Direction
(OP)
Hi All,
This may at first sound like a really basic question.
Does anyone know how manufacturers ensure a single phase motor runs in a specific direction i.e. for a angle grinder/bench drill etc.
And if there is a way of knowing this during motor construction, is it possible to reverse the direction or is it more cost effective to buy a new piece of kit.
I am guessing a lot of equipment is two direction anyway so it makes no odds but just wondered if there is a simple answer.
As you can tell, motors are not my strong point.
Thanks very much.
This may at first sound like a really basic question.
Does anyone know how manufacturers ensure a single phase motor runs in a specific direction i.e. for a angle grinder/bench drill etc.
And if there is a way of knowing this during motor construction, is it possible to reverse the direction or is it more cost effective to buy a new piece of kit.
I am guessing a lot of equipment is two direction anyway so it makes no odds but just wondered if there is a simple answer.
As you can tell, motors are not my strong point.
Thanks very much.





RE: Single Phase Motor Direction
The rotation of a shaded pole motor is determined by the position of the shading coils relative to the main windings. The rotation of a shaded pole motor is generally fixed however some models may be reversed by interchanging the end bells so that the shaft is on the other side of the stator. There have been reversing shaded pole motors constructed with two rotors on one shaft passing through two stators. One stator runs the motor cw and the other stator runs the motor ccw.
It is not random.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Single Phase Motor Direction
To that, one might add that angle grinders usually have universal motors with a commutator and are, in a way, DC motors that have been trained to also 'eat' AC. Their direction of rotation is determined by internal connections and can usually be changed if the machine is opened.
There are also small appliances like citrus presses that actually can (and do) start in random direction. They have no shaded poles and no auxiliary winding. Also, they usually/sometimes have a permanent magnet fine-toothed rotor.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Single Phase Motor Direction
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: Single Phase Motor Direction
So, I connected a Scopemeter and turned the mandrel by hand.
WOW! Lots of voltage there. Not for a weak heart.
See for yourself!
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Single Phase Motor Direction
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: Single Phase Motor Direction
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Single Phase Motor Direction
Is the motor in question a slow speed motor, to the point that you could manually turn it faster than normal operating speed?
Is this a type of synchronous motor with a multi-pole permanent magnet rotor. The direction of rotation depending on the position in which the rotor poles stopped in relation to the stator and the polarity of the first half cycle of current?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Single Phase Motor Direction
I told my wife that it *could* be nasty. I had tried it myself and knew what it felt like.
I don't know why it decides to start in one direction or the other. It 'wiggles' for a split second before it starts and then, the direction is purely random.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Single Phase Motor Direction
RE: Single Phase Motor Direction