Looking over the Pump Station ops I found EndX was not running; the other pump stations were fine.  The servo was on but output was maxed and pressure zero.  No response to remote manipulation.  Found VFD in OU3 fault and needing reset.  Restarted to normal running w/o issue.  Looking at the trends however, found this actually dropped at ~noon 21 Aug.  No alogged potential causal issues found.  This "Overvoltage--Running at Constant Speed" trip has occurred here before--will investigate.