DC motor testing at no load

[dithomas]

If I have an unloaded 1500 HP 700 VDC shunt wound motor how can I determine the voltage and current levels, starting from 0 volts and ramping up, that it would take to first get the motor to roll that run at full base speed. I know that to get to full base speed I will need 700 VDC and full field but what would be the armature current to account for windage and friction?

I know that this is a some what simple question that deals with a more complex situation.

Thanks in advance.
Dan

 

[Skogsgurra]

A standard windage and friction number is around 1 percent. You probably need to include armature losses, also - the AC field in the rotor of does produce some heat. A typical speed for such a motor would be around 1500 RPM and that is where the "convenient" 1% can be used. If there are wings (for cooling) on the rotor, you will have higher losses.

1500 HP is around 1 MW. 1% of 1 MW is 10 kW, which translates into around 14 A. So, I would expect anything between 10 and 30 A. There are so many unknown factors that one cannot guess any better. At least not me.


Gunnar Englund

http://www.gke.org

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