System not grounded is the fault that has shown up on a a couple Pentek Intellidrives for my local pump installer. One I know is grounded. We wired it. 1PH in 3PH out. 120/240.

Looking at the manuals explanation is of course, no ground, with the other being Line to Line voltage must be twice the line to ground voltage. How often does the drive check for this? Would a lightning transient be enough to trip the drive on this fault? He had two VFDs several miles apart trip with the same fault on the same day