Hello,
I work at a power plant.
A few days ago, our turbine tripped and shut down. After the turbine stopped, I noticed that the Atomizing Air Booster Motor was still running.
I expected the motor to stop when the turbine was shut down, so I would like to understand the logic behind this operation.

• Is it normal for the Atomizing Air Booster Motor to continue running after a turbine trip?
• What signal or control logic keeps it running?
• Is it controlled by a timer, pressure switch, temperature signal, or another condition?

Thank you for your support.

 

@97133FHD,

Let me guess--the turbine is a GE-design Frame 9E manufactured in Belfort, France. OR, the original turbine control system of the Frame 9E was replaced by GE with a newer version. And, the machine was burning liquid fuel (heavy fuel or naphtha) at the time the trip occurred.

It's best to provide as much information as possible so that you get the quickest, most concise answers possible. If the machine has Dry Low NOx (DLN) combustors it's also best to tell us that in the beginning. The type of turbine control system is also helpful to know, as is the type(s) of fuel the machine burns and what type of fuel it was burning at the time of the trip. But making us guess just means you may get the answer you are looking for after some back-and-forth, or not.

Usually, the AA (Atomizing Air) Booster Compressor motor only runs when the machine is being started or shut down while burning liquid fuel. If the machine was burning heavy fuel oil (crude; bunker) it's possible the AA Booster Compressor was started to help try to clear the fuel nozzle of heavy fuel so that it won't carbonize due to the residual heat in the combustor.

Usually, the AA Booster Compressor is only used when starting on liquid fuel and is shut down when the machine reaches FSNL (Full Speed-No Load). Some divisions of GE have made changes to the typical logic which was successfully used for decades (for various and sundry reasons, and often without proper testing/verification of the new logic--GE Belfort is infamous for this practice).

So, without a lot more information it's difficult to impossible to say for certain what the logic is that controls the operation of the AA Booster Compressor (and its motor). Telling why the machine tripped and what the alarms were at the time of and shortly after the trip, and when the machine reached zero speed, could also be helpful in providing the information you are seeking.