Hello, on some product pages of NEMA 17 stepper motors, how come they only list the rated current/phase and the holding torque without mentioning at what voltage? Is there some kind of default voltage that they assume everybody knows? What about the recommended voltage to drive these motors at maximum torque without damaging them?
There are four wires from each motor. I think they are used as control wires to control the speed, direction and amount of rotations. Where are these motors getting the voltage from to power up?
For a short answer in text:
Torque is proportional to motor current (but varies between 0 and a maximum for a stepper motor, depending on phase angle (Max torque at 90 degree phase difference between magnetic and electrical angles))
Motor voltage is a function of electrical properties of the motor. Each coil has copper resistance, and on top of that each coil has inductance. So at low RPM the motor voltage will be (very close to) DC resistance * Current, while at high RPM, the motor inductance will be the limiting factor. You need a lot of voltage if you want to change current though and inductor quickly. 24V is a common voltage used for a Nema17 stepper motor, (with driver!) DC resistance is probably so low that you would get fully rated current at just a few volts (the chopper in the motor driver limits the current to a set value). If you want to run the motor at High RPM, then more voltage is better. Use 36V or 48V if your stepper driver circuitry can handle this with a safe margin.
I am drawn between NIMA 17 and 23 stepper motors. Somewhere I read that NIMA 23 motors have higher torque than NIMA 17 motors but I have seen otherwise. If the torques are the same or very similar, is there any advantage in going for a NEMA 23 motor instead of a NEMA 17 motor?
If they both have rated current below 5A, is it better to get 30V 10A or 60V 5A? Both end up 300W.
AFAIK, NEMA only defines the physical dimensions of the motor, including mounting holes and shaft diameter.
The electrical part is a different issue.
I am drawn between NIMA 17 and 23 stepper motors. Somewhere I read that NIMA 23 motors have higher torque than NIMA 17 motors but I have seen otherwise. If the torques are the same or very similar, is there any advantage in going for a NEMA 23 motor instead of a NEMA 17 motor?
If they both have rated current below 5A, is it better to get 30V 10A or 60V 5A? Both end up 300W.
You'll have to post some part numbers to compare. There is more than just current and voltage rating. Read the torque specs, the winding inductance, etc.
Also specify your available power supply voltage. Often 48V is the max safe "low voltage" before you have to worry about additional safety precautions.
Probably best to start with the requirements (available space, torque, voltage, rpm) and go from there instead of deciding what motor you want and work backwards.