Hi,

The open circuit rotor voltage is the voltage measured on the terminals of the rotor under rotor open circuit condition.What are the major differences ,apart from an insulation point of view, between a motor rated secondary voltage 500 V and one rated @ 900 V.

Bob

Hi Bob

The output voltage is higher because there are more turns on the rotor.
In terms of performance, there should be no major difference except that the short circuit current will be lower and the secondary resistances will be very different for the same torque/speed points.
If you changed from one to the other, you would need a new secondary resistance starter to go with it.

Best regards,

Hi Marke,

Thanks for your kind reply. I have got a secondary liquid starter which was used for a motor rated at 1380 V secondary voltage and and 450 A secondary current. I am planning to use it for another motor rated 930 V secondary voltage and 320 A secondary Current. The short circuit secondary current will be limited by the current rating of the secondary short circuit contactor. I intend to adjust the speed torque curve to suit my load by adjusting the conductivity of the electrolyte.
Your advise please.

Nob

Hi Bob

As the SC current of the new motor is less than the SC current rating of the old starter, there should be no problem. You will have to play with the electrolyte to get the characteristics that you want.
The only other issue to watch for is the thermal mass of the electrolyte. If the starter was designed for a quick start, and you are no going to use it for slip control, you will have continuous slip energy dissipated in the electrolyte and it may get too hot.

Good luck,
Best regards,
Mark.

Thanks Mark. I shall keep you informed.

Kind regards.
Bob