fsxn155
Mechanical
- Jun 29, 2020
- 29
Dear All
Recently while stopping a 55 MW Generator Drive Steam Turbine, as per normal shutdown procedure given by Turbine OEM, Turbine load was feduced to 4 MW and Generator Breaker Opened. However Turbine Speed reached Overspeed Trip limit but unfortunately Turbine couldn't be tripped due to malfucntion of trip system. We were able to identify the cause of Trip system malfunction as well as reason for Control System not being able to mantainn speed at set point during the event.
Being from mechanical background, I just want to know is it standard procedure to open the Generator Breaker at certain minimum load for some reason from electrical side (reverse power etc.) and if so why not directly trip/stop the Turbine at certain minimum load rather than opening the breaker. (I believe as Turbine can trip at any laod, there must be protectons avaialble to prevent reverse power)
Appreciate if anyone can share the shutdown procedures followed at other sites
Regards
Recently while stopping a 55 MW Generator Drive Steam Turbine, as per normal shutdown procedure given by Turbine OEM, Turbine load was feduced to 4 MW and Generator Breaker Opened. However Turbine Speed reached Overspeed Trip limit but unfortunately Turbine couldn't be tripped due to malfucntion of trip system. We were able to identify the cause of Trip system malfunction as well as reason for Control System not being able to mantainn speed at set point during the event.
Being from mechanical background, I just want to know is it standard procedure to open the Generator Breaker at certain minimum load for some reason from electrical side (reverse power etc.) and if so why not directly trip/stop the Turbine at certain minimum load rather than opening the breaker. (I believe as Turbine can trip at any laod, there must be protectons avaialble to prevent reverse power)
Appreciate if anyone can share the shutdown procedures followed at other sites
Regards