vfd thermal protection

[gooseloony]

I was told that VFD's pump motors do not require thermal overload protection, true?

 

[RUWired]

I was told that VFD's pump motors do not require thermal overload protection, true?

Article 430.124 requires it to have protection.

430.124 Overload Protection.
Overload protection of the motor shall be provided.
(A) Included in Power Conversion Equipment. Where the power conversion equipment is marked to indicate that motor overload protection is included, additional overload protection shall not be required.
(B) Bypass Circuits. For adjustable speed drive systems that utilize a bypass device to allow motor operation at rated full-load speed, motor overload protection as described in Article 430, Part III, shall be provided in the bypass circuit.
(C) Multiple Motor Applications. For multiple motor application, individual motor overload protection shall be provided in accordance with Article 430, Part III.

 

[gooseloony]

That was my understanding of ALL motors but the MFG presented documentation indicating (though not marked "thermally protected") that it did not require individual thermal protection. Sorry I don't have the document scanned to post and don't recall the exact wording. But thanks for your response.

 

[RUWired]

Mybe it meant that the motor didn't need addition protection because it was built into the drive.

One of the main steps with drives is setting the tol protection .

 

[Christopher Otto]

You'll see motor manufacturers' application notes - like this one from Marathon, for example - state that their motors having inherent overload protection must not be used with a VFD.

Perhaps that's what original poster was thinking of?