ISSUE
On some ES7 installations, the drive has tripped on VSD COMM either upon startup or after several weeks or months of running.
ROOT CAUSE
The drive has a communication time out timer, where if a valid TOSVERT packet is not received by the controller within that determined time, as a safety precaution, it will trip the drive. This is done intentionally, in the event the controller permanently loses communication with the drive, it does not continue to run unmanaged. Historically, the time out timer has been set to 2 seconds. In the more recent releases of the Instruct firmware (2.124r008), that timer has been increased to 15 seconds. Despite increasing the time out timer, there are still occasions where the drive will trip on VSD Comm Error. Electrical noise within the system caused by the electronics (ie switching of the IGBTs, 3ph power running throughout the cabinet etc., all generate electromagnetic interference) is the most likely cause.
Refer to attached PDF for full details.