I was taught years ago that an electric motor's horsepower rating was voltage times current divided by 746. I have a new NOVA drill press with a Digital Variable Reluctance motor that can run on 115V or 230V and the HP is shown as 1.75 HP @ 115V and 2.0 HP at 230V. How is that possible? (I don't fully understand variable reluctance).

thanks ~ Peter

 

https://www.wisc-online.com/learn/c...au14208/the-variable-reluctance-stepper-motor

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the HP is shown as 1.75 HP @ 115V and 2.0 HP at 230V. How is that possible?

It could be due to fixed switching losses being a higher percentage of 115V than they are of 230V. Just a guess.

 

https://www.wisc-online.com/learn/c...au14208/the-variable-reluctance-stepper-motor

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thanks, but I guess I wasn't clear: it's not a stepper motor it's a continuous run motor.

 

It could be due to fixed switching losses being a higher percentage of 115V than they are of 230V. Just a guess.

thanks. that difference still upsets my apple cart!

 

It's because the torque/voltage relationship is not the same as other motors. The rotor is just a shaped slug of soft iron.

The torque vs voltage plot looks VERY much like the graph of magnetic induction vs current. After you reach a certain strength of magnetism the induction values stop increasing proportionality.

Same for your motor. The voltage doubles but magnetic induction strength doesn't double because it has already reached the "knee" of the linear portion of that response curve of induction vs current.

 

It's because the torque/voltage relationship is not the same as other motors. The rotor is just a shaped slug of soft iron.

The torque vs voltage plot looks VERY much like the graph of magnetic induction vs current. After you reach a certain strength of magnetism the induction values stop increasing proportionality.

Same for your motor. The voltage doubles but magnetic induction strength doesn't double because it has already reached the "knee" of the linear portion of that response curve of induction vs current.

Thanks so much! I knew that "something" had to be non-linear, but without knowing much (read nothing) about reluctance in the first place I quickly got lost.