My name is Greg. I work with Oregon State University's refrigeration department.
We have a 600 ton York YT centrifugal chiller with a variable speed drive.
Quite frequently it is tripping on "Loss of serial communications with VSD". We have checked the conductor connections and board plug-ins. We have followed a York field tech bulletin on ensuring the grounds are clean, used the star washers, and have made sure only one end of a shielded conductor's shield is attached to ground. Sometimes it can go for months with no problems. Other times it is several times a day I have to restore it. I can watch the lights (RX/TX Rcd) on the board the VSD talks to blink regularly, and then they don't blink or not in a regular pattern and then the chiller controller initiates a shut down.
Anyone have experience or has fixed something like this? At a couple grand a board I don't want to blindly swap parts.