Phase Current in a 3 Phase Electric Motor

[DGAero]

My inverter has a limit of 300 Arms and I am designing the phase connectors to the motor. Does 300 Arms mean that each phase sees 300/sqrt(3) Amps for me top design around?

Thanks!

 

[JoeStillman]

Welcome to the forum.

Typically, when an inverter is rated for 300A, that means 300A on each phase leg. For conductors between the inverter and the motor, use the motor HP rating and the corresponding FLA from NEC table 430.250 to size the wire per 430.22. The motor (and wires) need overcurrent protection too.. What sort of inverter is this? What is the motor for?

 

[winnie]

My inverter has a limit of 300 Arms and I am designing the phase connectors to the motor. Does 300 Arms mean that each phase sees 300/sqrt(3) Amps for me top design around?

Thanks!

What exactly do you mean by 'phase connectors'?

If you mean the three conductors between the inverter and the motor junction box, then as @JoeStillman says, those conductors will carry up to 300A _each_.

If you are talking about internal connections between the supply terminals and the motor windings, then you _might_ see a 1/sqrt(3) term, depending upon the particular motor connection. For example if the motor is internally delta connected then the current through a delta leg of the motor is 1/sqrt(3) the line current feeding the motor. Usually an installer isn't worrying about the internal connections of the motor, but the phrasing of your question makes me want to clarify this point.

-Jonathan

 

[DGAero]

Thank you all, these answered my question. I appreciate the help!