1303 oz-in Stepper to Gecko 210

[Jay Kyle]

Hello all,
I'm sitting here reading wiring diagrams, manuals, etc. trying to figure this out.

I have a set of steppers (MCG IH 34114) with the following possible configurations:
- Bipolar Parallel, rated current/phase = 9.0A, voltage = 1.8V, 1303 oz-in.
- Bipolar Series, rated current/phase = 4.5A, voltage = 3.6V, 1303 oz-in.
- Unipolar, rated current/phase = 6.4, vlotage = 2.56V, 920 oz-in.

The motors are direct attached (via coupler) to the ballscrews on my Industrial Hobbies style square column mill.

Given the limitations of the Gecko 210's, I'm not sure which configuration is opitmal for my mill. Any insight would be appreciated!

Thanks
Jay

[ger21]

Probably bipolar parallel at the Gecko limit of 7amps, which would give you about 1000 oz-in of torque, and the best high speed performance.

[drk]

You could also run the motors in a bipolar series configuration at 65-70 V but full current of 4.5A a phase without straining the geckos. Might just be good enough, see the motors torque/speed curve to see the tourque u get at the speeds u want.

[Jay Kyle]

Gerry,
You actually have touched on a question I've had, what happens when you use a motor that has a higher rated amperage than the gecko's. Which item limits the current, the gecko's or the drives.

Since the drives are direct connect to the ballscrews I imagine that low-speed torque would be more important than high-speed torque.

I've looked around for torque curves but all I could find for this motor were bipolar parallel.

Running in bipolar series sounds tempting as I think I would have the full power band, but would low speed torque suffer?

More confused than ever.

[ger21]

The Gecko's control the current, and torque is proportional to current supplied.

with bipolar series, torque falls off much faster as speed increases than with bipolar parallel, usually at least twice as fast, if not a lot more, based on curves that I've seen.