2 Phase Servo Motor Question 2

[gearcutter]

I have an AC, 115V, 2 phase, 60HZ servo motor system that I need to run on 50HZ.
Would lowering the frequency and leaving the voltage the same create a problem?



Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[Skogsgurra]

It depends.

The magnetizing current (assuming an induction type motor) will go up. That means that total current will go up as well. But not much, since saturation does not set in at so small voltage differences.

For PM motors, the load angle will increase to acommodate for the higher V/Hz ratio. This means lower PF and also higher current.

If your servo is not near thermal overload when run on 60 Hz, I think it will do quite well on 50 Hz. But check temperature vs all possible load cycles before letting customer have it.

OTOH a small autotransformer costs next to nothing.

Only problem then is that your speed will be 83 % of 60 Hz speed. That is true also w/o autotransformer.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[cswilson]

You say this is a servo system. To me, this implies electronic control through an inverter power stage with a front-end rectifier. If this is the case, the biggest effect will be slightly greater voltage ripple on the DC bus from the lower input frequency, and possibly greater heating in the bus capacitors. Most servo amplifiers run without noticeable performance difference at 50Hz and 60Hz.

Curt Wilson
Delta Tau Data Systems