Gas turbine is over shooting nominal demand speed by approx 400 rpm for more than 3 secs on start up.
Nominal demand speed is 11060rpm.
Turbine is being tripped from an Over Frequency trip from Generator Control Panel.
Generator is excited at 95% GT speed.
Why would the turbine be receiving a over frequency trip signal when the Generator is not synchronised ?

 

Gas turbine is over shooting nominal demand speed by approx 400 rpm for more than 3 secs on start up.
Nominal demand speed is 11060rpm.
Turbine is being tripped from an Over Frequency trip from Generator Control Panel.
Generator is excited at 95% GT speed.
Why would the turbine be receiving a over frequency trip signal when the Generator is not synchronised ?

Generator shall be tripped if frequecy is out of over/under settings. Please check setting of Frequency relay 81 which may be embedded this function in Generator control panel.

 

A fault in the communication link between the turbine control system and the GCP can cause a premature over-frequency trip.