Thank You. Other drives indicate ground faults and I’ve dealt with over voltage before but not associated with GF.
Any chance lightning could have done this while the motor was offline? $7K motor two years ago. I’ll be asked.
Generally speaking the motor has two kinds of insulation in the stator. All of the wiring has insulation on it to prevent turn to turn shorts. The slots are insulated from the whole coil. A ground fault means the integrity of the slot insulation is damaged. Faults can occur elsewhere but that’s what it is telling you. It is the end result of a motor failure.
With the motor disassembled you can often tell by the damage what happened. For instance if all the insulation is evenly burned, it’s an overload. If it’s only on one phase it was single phasing. If it is only the first couple turns on one coil it was a big surge. If it’s on every coil it was most likely VFD reflections from excessive cable length. If the bearings are “frosted” and they see fluting it’s often a common mode issue from a poor drive filter or cabling issues.
You should get an inspection report from your motor shop. If you don’t, time to start looking for a new one. This is automatic with every motor they receive. They should be running a test (Baker, PdMA, etc.) then pop the bearings out and insoect. Core loss after burnout to check if it can be rewound without restocking the core. You should be using that information to improve your motor installations to get the most life out of them you can. Good shops will generally just document and ignore most common failures unless you ask.
