text: <s>[INST] Powerflex 755 bus voltage HIM display does not match measured voltage Summary: Drive has failed, but HIM is not helpful in diagnosing the problem Over the span of a day, A 480VAC PF755 drive configured for CIP motion initially was reporting DECEL INHIBIT faults. Then it began reporting BUS OVERVOLTAGE faults. The end user noted that the bus voltage shown on the drive HIM reported 680V dc bus voltage. At the time of measurement, the line-in voltage showed 470VAC. The end user measured 240-300V bus voltage. That surprised me so much, I had him measure a second drive in the system. It measured 680V (or close enough to the HIM display of that drive not to question it). Remeasuring the bus voltage on the suspect drive, the user got 300V bus voltage, with voltage fluctuations as low as 0V. Replacing the drive got the system operational again. My concern is that the process values on the HIM are worthless. The HIM reported 680V bus voltage the whole time the user measured much lower. Any suggested explanations for this? [/INST] most likely the voltage feedback board is faulty therefore the HIM cannot display the correct value. \\n </s>