Powermax II stepper help?

[fyffe555]

OK, I'm confused about these steppers; Powermax II P21NxxC-Lxx hybrid series. what Voltage and current should you be running these at?

I think a few guys are using similar motors here so hopefully somone can tell me whats what. I have the pdf's that relate but the numbers do not add up. Cannot figure out what voltage I'll need and what power supply to build so haven't spun anything yet.

The motors measure 1ohm per phase.

On the label it states 1.75a bipolar series. PDF agrees and further says 3.5a bipolar parallel and 2.5a unipolar.

Label says power Po= 46W, Vs(dc) 65v & 1500rpm Is that 46w total for all phases? 65v doesn't make sense and can they really do 1500rpm? intend using ten tpi so aiming for 600rpm max

What ever, if you take 1.75a, 46W and 65v Ohms Law has a fit and it doesn't make sense, to me at least. If you take 1.75a and 1ohm then thats 1.75Vdc? If you take 46w/4 phases and sqrt(W*ohms) then thats about 1.7v.

So am I right to think that a 12v motor supply, current limited to 1.75a or whatever is going to work without letting out the magic smoke?

thanks

[ger21]

What driver are you using? For best performance, run them in parallel at 3.5a and as high a voltage as you can up to 65V, if your driver can handle it.

Gerry

[kong]

As ger21 said, use the highest amperage your driver card will support. There are some wiring diagrams over on the Xylotex website for the different configs. I'm using the xylotex board, and have them wired bipolar series (1.75A), and they are mighty good.

[fyffe555]

For the fun of it I was intending to build my own drivers/PS once I knew what I needed to output.

In the interim I have some IM483's which can output 3A rms 4A peak and 12-48vdc.

What relative performance could I expect with these motors in Parallel, Serial and Unipolar? they're supposedly 116ozin in Bi and 82ozin in serial but the torque curves drop off really fast in Bipolar and Unipolar seems to have higher torque in the 200-800 range?

thanks

Andrew

[bcromwell]

Originally posted by kong As ger21 said, use the highest amperage your driver card will support. There are some wiring diagrams over on the Xylotex website for the different configs. I'm using the xylotex board, and have them wired bipolar series (1.75A), and they are mighty good.

Am I reading this correctly, Pins 1&2 (A) 3&4(B) Are what is required for this stepper to be Bipolar?

[kong]

No, all eight pins are used, read the "installation bulletin" and it gives the pin outs of the motors, and how to wire them for series/parallel.

[bcromwell]

Originally posted by kong No, all eight pins are used, read the "installation bulletin" and it gives the pin outs of the motors, and how to wire them for series/parallel.

Ah I see it now, Thanks, I must have been looking at a 4 wire motor diagram.

[ger21]

Bipolar parallel will give the best performance. The higher the Voltage you feed them, the slower the torque drops off, so go with the highest possible voltage.

Gerry

[fyffe555]

Gerry, Thanks for the replys.

Have you anything to suggest about the Watt ratings? The pdf and the label both state 46W. 3.5a and 46W is only about 3.85V? How's that work? Is that 46W per phase? Hence my original post.

I'll be using a PWM driver with current limiting so I guess I'll just wire one up and see how it goes?

Is anyone else using these motors? If so what are you running them at?

Thanks again.. Now back to figuring out how to mount the end bearing and motor couplings....

[ger21]

Use the 3.5a and as high a voltage as you can supply, most people use around 24V. The motors have a 65V max. As long as you don't exceed the rated current for the wiring type chosen (parallel or series), you shouldn't have any problems. I always assumed that if you take the numbers in the .pdf, a*ohms = V, but after thinking too much I'm not positive that is correct. But if you stay at 24V or less, V shouldn't matter . Does this help?

Gerry

[fyffe555]

Gerry,

Yes it helps, thanks. As you say the numbers do not add up and it helps to work this through. I'll guess I won't really know until I end up spinning a motor and try a few wiring and power permutations and see what happens.

Andrew

[balsaman]

Andrew,

Everyone runs steppers at something much greater than the rated voltage. Then they use resistors or a chopper circuit to control the amps. It's the amp that make heat. The 65 volt rating on those motors is just the max volts the motors should see. They are actually ~1.7 volt motors and if you hook them up to 1.7 volts they will draw the rated current. The ohms law thing does indeed apply to these motors (and everything else).

The best way to run steppers is use the highest volt powersupply the driver can handle (65 volts max for these motors), and then set the current on the driver.

If you are using a xylotex driver the max is 30 volts or so. Use a 24 volt supply. The xylotex will handle the current limiting.

Eric