2 Speed Three phase motor

[picksbendy]

Hi,

I'm actually have zero knowledge in motors. But, I'm wondering is it possible to configure/set up a three phase motor to having 2 different speed? I'm trying to make a machine for shear forming that require 2 different speed for roughing and finishing.

Best regards,
Picks

 

[waross]

There are motors available in which the windings may be reconnected for two speeds. The speeds of a reconnected motor will be in the ratio of 2:1
There are also motors with two complete, separate windings and the speed ratios do not need to be a 2:1 ratio.
But, it may be cheaper and result in a better product if you use a Variable Frequency Drive and a standard motor. You will have a very wide speed range and will be able to run smaller three phase motors from a single phase source.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ccjersey]

Also possible to have 2 separate motors of different speeds connected to the load. Power only one at a time obviously. Your speed choices would be limited to standard motor speeds unless you can do some gearing/belting.

 

[edison123]

There are special windings called PAM (Pole Amplitude Modulation) which give ratios other than 2:1 from a single winding. They are complicated and need a knowledgeable rewind shop.

Muthu

http://www.edison.co.in

 

[picksbendy]

Thanks for the explanation and constructive ideas, it sounded a lot more complicated than i expected and requires very much in depth knowledge. Did some searching on VFD through internet, looks to me it's the simplest way to achieve the objective, please correct me if i was wrong about the technical knowledge behind it.
Will it be durable and reliable if the speed is switched between high and low frequently, for instance 1 cycle is 1 minute and for 500 cycles a day? (minimum)

 

[edison123]

That would be a perfect application for a VFD.

Things to note

1. The motor winding is suitable for VFD duty.

2. May be an additional external cooling fan for the motor since its own shaft mounted fan may not be enough at low speed.

Muthu

http://www.edison.co.in