Re: [CAD_CAM_EDM_DRO] Re: Power Supply-- more questions

In a message dated 1/4/2006 12:47:57 A.M. Central Standard Time,
hjjohnson@... writes:

I can't quite get 25 times my stepper voltage as that would put me over the
Gecko 80v rating. So I'm shooting for 78vDC to the drives. Therefore
78/1.4=56vAC 6.0A x 4 steppers =24A.



CAREFUL! I discovered that the actual current drawn from the supply by a
chopper drive is considerably LESS than the "motor current rating". It's the
WATTAGE you use to do the math! If the coils are, say, 3V x 4A, then TWO
windings draw 24 W. For 4 motors, you will have 96 W. total. So, if you have a
75 V. supply, 96/75=1.3 A, so a supply rated for 1.5 or 2 amp would do!
Amazing, yes, but I learned this by TRYING things myself, and it's true! You do
NOT need a honking-big 24 A supply! I'd probably be conservative and go for
4 amp supply just to be "safe", but MEASURE the actual current for various
motor-RPM's and it will boggle your mind! JRR


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