----- Original Message -----
From: "Matt Shaver" <mshaver@...>
Question:
The instructions that come with the board lists one of the specifications
as ".5-5 Amp Output Per Phase With Two Phase On". If I were to adjust the
drive current to 5 amps for all three motors, and all three motors were
stopped at a half step position, would the total current draw be 30 Amps
(5A drive current x 2 phases on x 3 motors)? Some links I looked at to
understand steppers and half stepping mode:
That is a good question and I don't know the real answer. From my
experience the input current draw is less than the total of what each axis
is set for added together (3 axis's set at 5 amp each draws less than 15
amp). On my power supply I have a number of seperate circuits with
individual breakers. When I was running 3 axis's at 2 amp each and was
connected to a 3 amp breaker I would pop the breaker occasionally. I am now
running 2 axis's at 4.92 amps (all I can get the controller to go up to) and
the 3rd at 4 amps and it is all conected to a 7 amp breaker and I have never
tripped it. I sort of asked Dan about this in determining what value to use
for a particular motor and despite his best efforts I am not sure if I
understand, but basically the draw is less than the amount the axis is set
for as the chopper circuit turns the current on and off so if you are set at
5 amps it is not a continious 5 amp draw, but a momentary 5 amps then 0 then
5 amps then 0 . . . . . . The result is the power supply sees a draw
less than the combine total setting as the 3 axis's are not all on at the
same moment.
I'm hoping to use this board to drive the original stepper motors on an
old
Bridgeport BOSS4 mill. These are really large motors made by Superior and
also Sigma. I was wondering if any one knew what the correct drive current
was for these. In the maintenance manual they talk about adjusting the
current to 8 Amps, but the original drive circuit was the RL type and the
Camtronics board is a chopper.
I set the motors to 75% of their rated current when using uni-polar motors
in bi-polar mode. This seems to jive with what I have seen when both motor
ratings are given.
Tim
[Denver, CO]
