MechMate CNC Router Forum - Transformer supply current versus Gecko output current . . . . .

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- 702. Power Supplies (http://www.mechmate.com/forums/forumdisplay.php?f=10)

- - Transformer supply current versus Gecko output current . . . . . (http://www.mechmate.com/forums/showthread.php?t=828)

Quote:

Originally Posted by bradm

Francis, I think all the evidence above shows that the formula is too conservative; you could probably get away with a smaller transformer. So your choice will work (you checked the inductance, on both types of motors to calculate your voltage, right?).

Hi Greg
Yes I have checked the inductance and applied the formula (sqrt of inductance * 32 = max. power supply voltage.)

Quote:

Francis, Its been mentioned many times in this forum (can remember which thread) that 300VA tranny is sufficient for the job. There will be a big saving in $ & space.
When you use unregulated power supply, the tranny will only supply when the motors as for. & most of the time they don't draw peak current & even more rear that all motors draw peak current at the same time.

Hi Ken
I did see all that evidence but I was a bit "scared" as I will be doing 3D work all of the time.

Quote:

Francis I have used a .75 factor and feel that I have wasted it - it is hardly anyday over the ambient room temperature

i have just wasted more money there - I also consulted with Anil who has a good command over electrics and electronics and his suggestion was for 0.5 factor and that too I think will never get hot

RGDS
Irfan

Hi Irfan,
You were even more worried that me about power supply! .75 factor is huge.

Thank you for the input, I think I will end up going slightly bigger then .5 factor, wich calculates to a 500VA tranny for me.

Gerald, yes that is what I meaning to say. This was the original thoughts.from the forum.

The KL34H280_45_4A motor has 6.8 mH inductance, It can be used with power supplies up to 80VDC (32 X SQRT(6.8) = 83VDC. 80VDC is the MAXIMUM voltage that the Gecko stepper drivers can handle.) 18 amps would all full speed under all conditions.

The KL34H280-45-8A motor has 2.2mH inductance when wired either half-coil or bipolar parallel. It can be used with power supplies up to 47VDC, using that same formula shown above. 25 amps would allow full speed under all conditions.

I would use a 70VDC power supply for the first motor to allow for power line variations. I would use a 35VDC to 40VDC power supply for the second motor, also to allow for power line variations.

I am wired up bipolar parallel.

If for any reasons that you must use an Antek tranny, Oriental motor, and Gecko Drivers; It is ok to run the motors at lower voltage to suit the Gecko max voltage rating or lower... This will lower the max speed, I wouldn't know how much lower but my gut feeling tells me they will be fast enough for the job. even at 35~40Vdc