Yet another power supply question!!

[chas]

Actually just need some verification.

Using powermax steppers 4.6a unipolar / 6.5a parallel bipolar.
2.71v

2 phase (6.5 *2) 13a * 3 motors (13 * 3) 39a.

Using gecko 201's so I only need 65% of total amps (39 * .65) 25.35a

I plan to use a 24v 12a power supply.

Will this power supply work, seems to me that I will be under powered??
Or am I totally confused now!!

[tachus42]

You can work it out this way - each phase uses 6.5A * 2.7V = 17.5 Watts. Total for 3 motors is 105 Watts. Your Power supply is 24V * 12A = 288 Watts. So you have plenty of margin.

This is assuming the drives are 100% efficent and the steppers are stationary. When the steppers are rotating they generate back EMF which needs to be added to the 2.7 Volts in the caluculation. I haven't seen back EMF quoted by stepper manufacturers often but when it is it seems to be in the order of a volt or two per 1000 rpm.

Still given the unknowns with a 180% margin over the basic calculation this power supply will be fine.

[Mariss Freimanis]

1) Use the unipolar rating.
2) If the motor is round, multiply that by 0.66
3) Multiply that by how many motors you plan to use.

For you that is Amps = 3 motors ( 4.6A times 0.66) = 9.1 amps from supply
It the motors are "square", then Amps = 3 motors times 4.6A = 13.8 amps

Mariss

[chas]

Mariss,
The motors are actually octogon!!
Powermax stepper motors
P22NSXA-LNN-NS-02
Would that count for round or square??
Thanks
Chas