13 replies to this topic

[3rd party JKor]

So, I have a bead on a cheap 90VDC motor for my mill (125RPM, 90in-lb). The problem is powering it. I do happen to have a 0-60VDC 10A power supply. If I ran it on 60VDC, does it just affect the rpm or does it drop torque as well?

[DR0NE]

So, I have a bead on a cheap 90VDC motor for my mill (125RPM, 90in-lb). The problem is powering it. I do happen to have a 0-60VDC 10A power supply. If I ran it on 60VDC, does it just affect the rpm or does it drop torque as well?

It will drop the torque. What amperage is the motor rated for? Torque will vary by the square of the voltage applied from what I referenced.

[3rd party JKor]

motor is 2.3A, I believe.

[davelew]

The simple way of thinking about a DC motor is that RPM is proportional to voltage, torque is proportional to current. This isn't exactly true in real life due to things like parasitic resistance and inductance, but it's pretty close.Your 125rpm motor should run at about 83rpm when run at 60V instead of 90V. The torque should be roughly the same, assuming you can get enough current to it.

So, I have a bead on a cheap 90VDC motor for my mill (125RPM, 90in-lb). The problem is powering it. I do happen to have a 0-60VDC 10A power supply. If I ran it on 60VDC, does it just affect the rpm or does it drop torque as well?

[DR0NE]

This page shows you how to figure out what will happen: https://www.motortech.com/BULL_E-1.htmAnd they do a good job of some of the math behind it here: https://lancet.mit.e...rs/motors3.html

[Stout_fan]

Well....DC motors have brushes.brushes make sparks.Mills make dustdust can ignite wit a spark....ergo: DC motors are not a good idea for mills.

[xd_haze]

Sure, but if the motor is TENV, I wouldn't worry about the sparks.Mike

Well....DC motors have brushes.brushes make sparks.Mills make dustdust can ignite wit a spark....ergo: DC motors are not a good idea for mills.

[Stout_fan]

Sure, but if the motor is TENV, I wouldn't worry about the sparks.Mike

A big IF,I saw nothing in the OP that indicated that.

[SchwanzBrewer]

its not necessarily a DC brush motor. There are lots of DC brushless motors as well. So long as the motor is in a housing the likely of it throwing sparks is nil.

[xd_haze]

I don't know where I thought I read that! My mistake.

A big IF,I saw nothing in the OP that indicated that.

[3rd party JKor]

It is indeed totally enclosed.

[Stout_fan]

Then please ignore the last 17 posts arguing this point

[Stout_fan]

JK, I noticed we totally sidestepped your question.But or advice is worth exactly what you pay for it :cheers:To answer your question, magnetic force is equal to n * I. Number of turns times the current.and...E=IRI is equal to the EMF (volts) applied divided by the resistance.But it isn't that easy. In moving magnetic fields you have a back EMF generated by the rotation.So it is really E(applied)- E(back)=E total.Back EMF is proportional to speed.So the lower voltage, gives you proportionately lower speed, and torque.Linear is a good approximation.Hope this helps.

[3rd party JKor]

Yes, it is helpful. Now I need to know where to find a cheap 90V supply.