I have a 900 ton Trane CVHE that has a Fastpak control panel conversion and a Robocon VFD starter. The VFD and fastpak were installed in 2000 and have been operating fine until recently. I am now experiencing a Phase Loss failure at startup. We have disabled the voltage monitoring in the UCP setup. I have also swapped the starter panel, CT and power starter transformers, swapped the Chiller module and rewired the CT's and still get a phase loss on start initiation. We have put an O scope on the VFD to verify the SCR gates are firing correctly. We have replaced the 1CR relay and still no luck. The VFD can be started and manually controlled so we are not seeing any issues on the VFD or on the Fastpak to determine where the start issue is. With the VFD running all amp reading on the fastpak are within 2% of each other. We have also increased the starting torque boost in the VFD for a kick start effect no luck. Trane Literature for the fastpak indicates the processor needs to see 20% of motor FLA within .7 to 1 second of a start command. The CH531 has an adjustable time delay to look at the initial inrush but I cannot find any adjustment areas in the Fastpak, though the literature indicates it should be programmable from 1 to 3 seconds. Does anyone have any ideas on a next step to determine how to resolve this issue? Is it possible to disable the phase loss protection, the VFD has in its software?