Stepper motor question:

[HenrikOlsson]

Stepper motor are meant to be driven by constant current drivers. In the good old days you had unipolar motors (center tapped windings) and drivers with BIG series resistors to limit the current to whatever the motor was designed for. These days stepper motor drives senses the current and control the output bridge (PWM) so that whatever current you set the driver to is what the motor gets. (And they sin/cos modulates the phase currents to get microstepping).

You basically have to use a much higher voltage than what the nameplate rating says in order to counteract the inductance of the winding, if you don't you'll have a massively underperforming motor. Usually 10 to 20 times the rated voltage is common but sometimes it can be even more. I'm not surprised by the 250V figure mentioned for large NEMA42 motors.

If you DO apply 5V directly across that motor winding you will damage the motor. You MUST limit the current to whatever the motor is designed for - one way or another. If there's no current rating printed on the motor, measure the resistance of the winding and calculate using Ohms law.

[rocket_troy]

Good explanation Henrik and my bad - I was feeding that voltage (it was actually 230V not 250V) into the driver, not directly into the stepper.

Troy