Hi, in the industrial control cabinet I'm designing there is a power supply with 24Vdc 20 amp output which powers several circuits with overcurrent protection for each circuit: PLC, relays, but also some small stepper motors. Now my question is if the stepper motor circuits can be considered as control circuits, or should be seen as power circuits.

In case of power circuit, the wire colors should be different and how about the short circuit rating of components on the output side of the power supply?

 

Use fuses or breakers that can interrupt the maximum fault current (in 24 V systems, high fault currents are less likely but not impossible).
Check manufacturer specs for your stepper drivers: Some expect external fusing and have max current/voltage specs.
If components have low SCCR ratings, and your 24 V supply can dump high short-circuit current, consider current-limiting fuses or electronic protection to limit damage.

 

Yes but in terms of UL508A, are these stepper motors supplied by a 24Vdc power supply considered a power circuit or control circuit. This has an effect on the requirements for SCCR and wire colors by the rules of the UL508A standard.

I actually want to regard them as control circuit, together with the PLC and IO supplied by the same power supply. But I'm not sure if the stepper motors can be categorized as control circuit by UL508A since it is a actually a small motor.

Has anyone experience with this?

 

How is everything going? Any update?