Our machine is GE6fa Gas turbine (natural gas fuel). At TTRF 1198c mode will change over to pmss to ppm. Why this change over required at low ttrf? what will happen if mode keep running in pmss mode?
Simply the answer is it won't work. This a Staged combustion system which goes through various combustion configurations dependent on calculated combustion Temperature TTRF. This will give best stability and lowest NOX through the load/unload range.
Try using the search box in the top right corner of Control.com, there has been a lot of previous write ups on DLN.
Try reading your manuals (usually the first place to go) and get an idea of how the DLN system functions with load changes then start to monitor the system.
This is a really poorly formed question. 1198 deg C is equivalent to> approximately 2188 deg F, and that's probably very close to the rates during temperature of the turbine in question. Meaning that's a relatively high firing temperature.
Further, you haven't told if the combustion mode transfer you are referring to is occurring during loading or unloading.
Why do you believe the unit should remain in Pre-Mix Steady State?