Re: Bridgeport Stepper Motor (Amp Rating of motor)

Gary,
There are 2 different motors (sigma and superior). Look at the
terminal block at the back of the motor. The Sigma has two rows of
four terminals while the Superior's terminals are arranged circular. I
am assuming you got the motors from a series 1
Remember these current ratings are from the Original Bridgeport Series
1 maintenance manual. They are for UNIPOLAR wiring only.

The service manual implies that 8.2 amps should be the static holding
current. I am assuming that is per coil and that holding there should
only be 2 coils energized. (There are 4 coils) The manual makes no
reference to the current rating being different between the two
motors. Actually I think it's more complicated than that because I
think the BP control was a half stepping driver. Now we're in the
realm where I don't know nuthun'.

I do have pictures of ocilloscope traces for several motor states. I
wish I could make more sense out of them.

If we could get ahold of the original Sigma or Superior specs that
would be much better.