Changing of 4 poles to 8 poles motor
Changing of 4 poles to 8 poles motor
(OP)
Friends, is it possible to convert a motor which is 4 pole to 8 pole motor. How will i do it? i dont have some data coz i was only asked by this. i am very curious about this.. i didnt find answers from books so i posted my question hoping somebody would help.. tnx





RE: Changing of 4 poles to 8 poles motor
If it is three phase you could always run it on a frequency inverter drive..
Jeff
www.motors-direct.co.uk
RE: Changing of 4 poles to 8 poles motor
RE: Changing of 4 poles to 8 poles motor
<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032
RE: Changing of 4 poles to 8 poles motor
As Nbucska said...probably better to get a new one!!
Jeff
www.motors-direct.co.uk
RE: Changing of 4 poles to 8 poles motor
A rewind of the motor from 4 to 8 pole is probably possible, if the number of slots is enough (48, 72, ...).
The cooling is not so good because of the low speed if the van remains. So you have to decrease the rating.
And you will get a low power factor (big air gap).
RE: Changing of 4 poles to 8 poles motor
RE: Changing of 4 poles to 8 poles motor
The principal compromise is in the magnetic circuit. It will not work optimized handling the new 8 poles magnetic distribution. The back iron will handle very low flux densities but the teeth will be highly saturated. The winding that will produce acceptable magnetic circuit saturation will probably result in less than 1/2 of the original 4 poles output Power (HP). The power reduction will lower the motor losses but a temperature rise test must be done to ensure that the actual cooling fans ( at lower speed) provide cooling into acceptable operating temperature rise.
RE: Changing of 4 poles to 8 poles motor
In your application you might need a seperately powered cooling fan.
If the machine is going to operate the motor at close to it's new rating, you would be better off getting a new motor. If getting an 8 pole motor is a problem, then a VFD and an oversize 4 pole motor is your best bet.
In 1 plant where I worked some of the thread rolling motors used 40 horsepower 10 pole motors. Instead of trying to get a replacement 10 pole motor they put in 100 or 125 horsepower 4 pole motors and used VFDs to feed them 24 Hertz power.
Mike Cole, mc5w@earthlink.net
RE: Changing of 4 poles to 8 poles motor
In some cases, All you have to do is to reconnect the groups to a consequent pole connection - all group ends are positive. This is the standard connection for one winding, two speed motors. Usually you would have to rewind to get the short winding pitch used in multispeed motors.
The motor also must be re-rated to constant torque (1/2 HP) or variable torque (1/4 HP). If you need the same HP rating (twice the torque) you're out of luck. This requires a much larger motor for most of the reasons stated.
There are a lot of other hooks, of course, which may cause problems depending on your application.