Condenser water box outlet valves automatically close

We have a 450MW CCPP with 2CT+2HRSG+1ST. For condenser cooling we have two cooling water pump (CWP) having 29000 m3/hr capacity each. When one CWP trips due to bearing vibration/temp or winding temp the condenser water box outlet valves close automatically. The valves are in auto mode. Our I&E team is trying to find out the reason but still they did not find the root cause. Our DCS is MAXDNA.

Did anyone face the same problem? If yes please kindly inform me how to solve the problem.

Thanks,
Rokan