2-Pole vs 4-Pole Motors
2-Pole vs 4-Pole Motors
(OP)
Can anyone tell me other than speed where I would want to use a 2-pole motor instead of a 4-pole motor and vice-versa?

Thanks
Johnster

Thanks
Johnster
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RE: 2-Pole vs 4-Pole Motors
RE: 2-Pole vs 4-Pole Motors
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RE: 2-Pole vs 4-Pole Motors
RE: 2-Pole vs 4-Pole Motors
Vibrations on this kind of 2 poles is a big problem, either for the balancing stability (i.e. termal bow) either for the twice line frequence component)
RE: 2-Pole vs 4-Pole Motors
4-pole does a little worse on power factor and a little worse in core losses. 2-pole does a little worse in friction and windage losses.
If you start looking at efficiency, don't ever overlook the driven load which usually is where most of the losses are. (motors typically above 95% efficiency, pumps often 60% efficiency). The losses in the pump are tied to how it's sized and speed is a big part of that whole process.
I agree with the last two posters on the subject that 2-pole motors by and large cause more maintenance costs over their lifetime than 4-pole motors. 20% of our machines cause 80% of our maintenance. Of those 20%, 80% are 2-poles wherease only around 50% or less of all our machines are 2-poles. In other words, a disproportionate share of our problem-machines are 2-poles.
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RE: 2-Pole vs 4-Pole Motors
But in what circumstances wouldn't the speed matter? If you had a variable speed drive application you might think that the number of poles is a variable but you would probably still go for the machine most closely matched to the maximum required speed. For example, if you needed a maximum speed of say 1500-2000rpm, the best choice is still a 4-pole machine because you would need a larger size (more expensive) 2-pole motor as it would be running at below its rated voltage.
RE: 2-Pole vs 4-Pole Motors
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