VFD's and motor rotation

[bloomquist]

we recently sent a motor out to be repaired. Just the other day we installed it on the same press we took it off of and the motor, when bumped, went in the reverse direction even though the phases were wired up correctly. My question is could the vfd that drives the motor have reversed the rotation or just simply the windings being mixed up at the motor repair center have caused this, also, have any of you ever seen this in the field? Thanks in advance for any replies.

 

[LionelHutz]

A VFD will output ABC phase rotation in forward and CBA phase rotation in reverse regardless of the input phase rotation. If the motor goes backwards when wired then maybe the leads were labeled wrong.

 

[jraef]

Sounds as though your rewind shop didn't bother to mark your leads when you brought it in, so when they gave it back it was not the same. That would have been a courteous step, but is not uncommon. 3 phase motor direction is irrelevant to wire numbering; in other words it is what it is. That is why it is ALWAYS important to check rotation on re-installation.