Motor starter and VFD

[cppoly]

If a VFD is used with a motor, is a motor starter required to be used in addition to provide the motor overload protection? Or is overload protection typically provided in the VFD as well?

 

[chuckgassmannm]

The vfd does provide the motor protection. In the parameter settings you can set the amperage for the motor.

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[cppoly]

Thanks

 

[Besoeker]

If a VFD is used with a motor, is a motor starter required to be used in addition to provide the motor overload protection? Or is overload protection typically provided in the VFD as well?

I wouldn't and I don't see the need for it with a VFD but I don't know if your code requires it.

 

[kwired]

One of the more typical exceptions to this is if a single VFD is driving multiple motors, then you would need individual overload protection for each motor. But you should connect it so it gives a fault input, loss of enable input, or a stop command to the drive and not just take that one motor directly off line when it trips on overload.

 

[Besoeker]

One of the more typical exceptions to this is if a single VFD is driving multiple motors, then you would need individual overload protection for each motor. But you should connect it so it gives a fault input, loss of enable input, or a stop command to the drive and not just take that one motor directly off line when it trips on overload.

No dispute with that.The OP mentioned "a motor".

 

[cppoly]

One of the more typical exceptions to this is if a single VFD is driving multiple motors, then you would need individual overload protection for each motor. But you should connect it so it gives a fault input, loss of enable input, or a stop command to the drive and not just take that one motor directly off line when it trips on overload.

Thanks for that tip.

 

[petersonra]

If a VFD is used with a motor, is a motor starter required to be used in addition to provide the motor overload protection? Or is overload protection typically provided in the VFD as well?

The short answer is no. The VFD provides the overload protection to the motor.

However, it is not unusual to have a contactor involved, either on the line or load side as a supposed safety measure on theory that the hard break of a contactor is somehow "safer" than relying on the VFD to shutoff. I think this proposition is moderately dubious, but it is not an uncommon practice.