Basic Motor Voltage Question

[pzzamakr1980]

Im looking at replacing my new lathes motor with a single phase AC or a DC motor for variable speed and have a couple questions.

When a motor is marked for 90volts, can it use 180 volts, and if so what will happen. Someone told me that the rpms will be doubled at 180 volts if the motor is rated for 90 volts and a set rpm at 90 volts.

If I go single phase ac, would I be able to use those variable speed control rheostats they sell for 20 bucks. I would be using a 3/4hp to 1hp motor and 110 volts. How do those work, and what do you lose with using them.

Thank you

[Al_The_Man]

The SCR or PWM drives by KB or Baldor can run a 90vdc motor with the 120vac version or a 180vdc motor with the 240vac version.
You can obtain manuals and info on both sites.
You are better off to get these than the ones sold for DC Treadmill motors, which have a start prevention circuit that ensures you go down to minimum speed before start.
Al.

[pzzamakr1980]

I understand what you use to power the motors but the question is, what happens when you increase the voltage to the motor? Beyond the rated motor limit.

[Al_The_Man]

If you run a 90 volt motor off of 240v version you have to limit the speed pot, otherwise you may cause damage to the motor if too high rpm.
Some models can be set by jumper.
Al.

[pzzamakr1980]

Okay gotcha. So an increase in voltage will be an increase in rpm. Thank you Al