3 phase motors

[Reesh14]

I have a question regarding the phase of a motor and poles of the circuit breaker for the motor. If I have a panel feeding a 3 phase motor, is it required that the circuit breaker must have 3 over current protection devices (3 poles)? Or for at least 15A and 20A circuits for small motors, can a single pole be used on the panel? I am just confused between the relation of phase and poles. Any advice is much appreicated, thanks.

 

[dpc]

For a three-phase motor, you'll need a 3-phase circuit breaker (NOT 3 single-phase breakers). Forget about poles and just think phases. You might also need an electrician to help you out.

 

[aolalde]

As DPC stated; for complete protection you need 3 over current protection device, one per line (some people call the lines "poles" but that creates confusion).
The magnetic poles of a 3-phase motor are created by the winding array and are those defining the synchronous rotating speed of the magnetic field.

In past, only two over current protection devices were used to protect a 3-phase motor, but that practice has proven to be inadequate.