Re: Power supply voltage.

Hi Gerry,
I had some excerpts from earlier emails on the same issue, the way
I brought the mains down was to use a line adjusting transformer
to bring 240 to 208. On eof these would bring your setup to below
83 volts. Really I think 65-75 volts is ideal for the G201/G210's
Thing run cooler and quieter. Read all the way to the bottom...
( they're in newest respons first order...) -Lee

Mike Snodgrass,Jon Elson, Lee Studley

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Hi,
After some ribbing and empirical observations on motor heating,
I've decided to reduce my G210 power supplies to around 65volts for
my nema42's. I used a variac to test the different voltages and didnt
notice any benefit in running above 70volts. Everything just ran
cooler at the lower voltages, and modern steppers work well there.
I'll rewind my master autoformer to bring the mains down
some more. Currently it has 20 turns, which I'll increase until I get
the desired output from the secondaries of the power transformers.
All gauges being used are oversized for safety. ( Warning :Dont wind
your own until you know what you're doing ;-)
-Lee

Mike,
I have one as described by Jon. Its yours for $30 plus shipping if
you want it. Its a 1KVA+ 240/208 can be used for 120/104. Heavy
guage wiring. Unused, about 4" cube as described. Its just sitting on
my shelf now. I ended up making an autoformer from some monster
transformers that came with my mill. This one I bought to observe how
they are made. I could have used it in my app, but I'm a glutton for
punishment and had to try hand winding for the experience.
-Lee

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
Bummer! it seemed like a good one. Is there another way to trim
the voltage other than huge , hot, nasty, power resistors or bulky
variac?
Power resistors will not "trim the voltage", either. They will
cause a voltage drop that varies with current draw.
There are voltage adjusting transformers (usually autotransformers)
available for converting 208 - 240 and 240 - 208. These are often
used to run
240 V air conditioners, or other mid-size motors, in locatins where
120/208 3-phase power is the only thing available. You should be able
to find them
at air conditioning parts shops and electrical contractor suppliers.
Because the core only needs to handle the difference Volt-Amps, these
transformers
are quite small. About a 4" cube, weighing maybe 6 pounds. I don't
think
they are expensive. I'll bet Grainger has them, too.
You can cut your voltage to 86% of what it is without the transformer.
You'd wire the line input (either 120 or 240 V) to the terminals
marked 240 V and the power supply would be connected to the terminals
marked
208 V. If you were supplying 120 V to your transformer before, it
would now see 104 V. This should help bring your ~80 V down to 69 or
so,
safe for the Gecko.
Jon




--- In CAD_CAM_EDM_DRO@y..., "WUKSTA" <gerry@z...> wrote:
> I am currently in the process of converting an
> engine lathe to CNC using Mach1 & G201 drives. I am
> using Nyden Nema 34 stepper motors rated @ 2 amps, 7.6
> volts. These are 6 wire motors, half-winding connected.
> I am using a machine tool control transformer.(ie:
> 220 to 110 or 440 to 110). If I connect 110v AC to
> the 440 taps I get 42 volts DC. I have tested this using
> Mach1, & both motors run very smooth @ 1000 steps per rev.
> without any lost steps.
> If I connect 110 v AC to the 220 taps, I get 83v DC.
> I would like to try this voltage but, the G201's are rated
> for 80 volts max. Will this extra 3 volts damage the G201
> drives?
>
> Thanks:
> Gerry