Re: Stepper motor vs amps per phase question???

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:

> In a message dated 8/29/2004 11:34:05 PM Central Standard Time,
> davemucha@j... writes:
> If I understand how steppers work, I believe they switch back and
> forth from there phases, and therefore a stepper that requires 3

amps

> per phase, only needs a total of three amps, because of the

switching

> process....... or does it?
>
> You are correct. A 3 amp rating is for the total motor.
> No, no, no!
>
> 3 amps per phase is only HALF the total motor-current rating. EACH

of TWO

> phases uses 3 amps, for a total of SIX! The phases switch

POLARITY, NOT

> "on/off"!
>

You are correct that the motor uses 3 amps per phase, but since no
two phases are energized at the same time, the motor never uses more
than the 3 amps.

In point of fact, when a chopper driver is used, LESS current will be
used as the duty cycle of the chopper will reduce the current used
even more.

AND in additon, the back EMF will feed the motor with power so even
less of a power supply needs to be used.

Per Mariss's white paper, the total use will be 2/3 of the motors
rated current when wired in single coil for 4, 6 and 8 wire motors,
or parallel in 8 wire motors. and only 1/3 if wired in series on 6
and 8 wire motors.

If you are running a UNI-Polar motor with current limiting resistors,
you need to select the resistor for the amp load it will be seeing.
nameplate if single coil or 1/2 if series connected.

So, if using three 5 amp rated motors in series winding, you can
double the voltage and use 10x to 50x of namplate voltage and half of
the current. for the 5 motors, you can use a 5 amp total power supply.

if single coil, then you can use a 10 amp power supply and 5 to 25x
nameplate voltage.

If you want more reading, check out the white paper

http://www.geckodrive.com/support.htbml?order_id=

Dave