Let me start by saying that this has been an ongoing issue for years and we have had multiple inside and outside contractors look into this. Many outside contractors thought they solved this issue by changing the VFD parameters. So far this issue still presents randomly without any indication of the obvious. We are thinking about swapping the VFD with a Yaskowa VFD, however this does not explain root cause of the problem.
We are experiencing a shut down of 2 TRANE rtu's at the same time. one unit is a 25 ton and the other unit is a 30 ton. Both units are experiencing an alarm 13 code for overcurrent on the VFD. Fluke data loggers show a momentary amp draw spike past the VFD setting and we have been puzzled as to what is causing this. These units do not have the power exhaust so we sometimes experience building over pressure. I was hoping that some one having the same experience could provide a solution and an explaination for what is happening on our units.