5KV Synchronous motor Trip

[adityalagudu3291]

We have 4160V, 500HP Synchronous motor tripped yesterday. There are no flags on the GE multiline relay and the PF trip is disabled on the relay. We did the Megger, Temp measurement, PI on the motor, everything is normal. This Motor is 25 years old, and the excitation is not AVR controlled, it is through a Rheostat. There is no fluctuation observed on the upstream. There is no overvoltage or under voltage when the trip happened. What could be the other things that need to be looked into on the synchronous motor trip?

 

[Jraef]

"Tripped" is too vague of a description to be useful. Is the Multilin relay a Motor Protection Relay (MPR) like a 469 or 369 relay or is it just the Synchronous Protection Module (SPM)? If it is an SPM and the problem was with the motor load, the SPM would not necessarily report it. If there is no MPR, is there an Overload Relay?