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Originally Posted by Astro
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Thanks for the link. 10X power out of a motor ... perhaps it is wound for a much higher voltage than the original (my search showed 1800 rpm, 60 Hz, 230/460V) and perhaps they balance the rotor so that it will spin faster?
Lets see - I have seen curves for standard induction motors that show maybe 3X - 3.5X the torque at the top of the operating curve with over 4X the rated current. I have not been able to verify any of this with measurements. But lets say they can get 3.5X the torque for a short period of time.
And I have read about some of the boys in Australia and New Zealand spinning 50 Hz/1500 rpm motors at up to 5000 rpm. I'm not sure that I would go that far ...
At 3X the max rpm, you could get 10X the power ... 3.5X the torque and 3X the rpm .. if the torque held constant above rated speed. It does not. The torque drops relatively linearly with speed over rated .. so that does not work.
But if you raise the maximum voltage WHILE you overspeed the motor, keeping the current constant as you go above rated DOES work for keeping the torque constant as you overspeed the motor ... so a 230V motor running at .. 690V .. could have 3X the speed AND maintain the torque.
If they are re-winding the motor anyway, maybe they can re-arrange the coils, putting them in parallel instead of series? That could drop the voltage from 690VAC to a reasonable value ...
Can you share info on these custom wound motors? Voltage, speed and torque?