Re: Surge Voltage?
Depending on the age of the ASCO ATS it may or may not have an In-Phase-Monitor, an easy way to check for in phase monitor and to verify the monitor is working is to place a multi-meter (analog works best) across any phase utility to generator (same phase) and watch for a reading close to zero at transfer. The meter should be approaching 0 vac and then transfer.
Out of phase transfers (depending on the type of load) can cause large impulses. The out of phase transfers damage the contacts of the ATS and can cause other problems as you have seen.
Older ATS's can be retro-fitted with an In-Phase-Monitor, though it would probably be cheaper to upgrade the complete ATS controls panel. Newer ATS' have DIP switches to turn on or off the IN-Phase-Monitor, check your ASCO manual.
What are the PT's utilized for?