The stepper works as an AC generator when you turn it. If the 2 leads of a winding touches each other the generator is shorted and the force needed to turn it gets much larger. If you short out all windings this way, you should not feel the detent, just a strong resistance to turn. Try to turn it faster and the resistance increases. You don't hurt the motor doing this unless you turn it faster and more forceful than you can do it by hand.
I have understood that one use of surplus steppers is as generators for windmills. It makes sense as it is designed for minimum losses. |