On frame 9E Gas Turbines(Mark IV), if additve dosing panel trips or additive flow rate becomes nil while m/c is running on furnace oil(Our GTs always run at base load) then it converts to HSD on auto & also takes shutdown command. Now if m/c is not restarted with in two minutes then boiler(HRSG) trips (while GT is running in combined cycle mode).

Now as far as Siemens V94.2 Gas turbines are concerned, if dosing panel trips while GT is running on LSFO then it only converts to HSD on auto i.e. no shutdown command.

Actually in case of GE Frame9E turbines, When additive dosing panel trips or additive dosing stops for some reason. A relay picks up because of no flow rate of additive & initiates a signal to heavy fuel permissive check relay because of which fuel changeover command to HSD is initiated. Now same signal of no additive flow rate also goes to turbine normal shutdown relay. In addition to this signal, turbine normal shutdown relay also takes into account a signal about position of fuel changeover valve (pneumatic operated). If position of this valve is not towards HSD within 10 seconds of initiation of additive no flow rate signal then turbine will take shut down command. Fuel changeover valve takes about 20 to 25 seconds to change its position from furnace oil to HSD. So, if we increase delay in turbine shutdown command signal from 10 to 30 seconds then with in this time of 30 seconds changeover valve would change its position towards HSD & hence there will be no shutdown signal (as conditions for shutdown would not meet because of changeover valve position would be towards HSD). Result would be that turbine will be running on furnace oil at base load for 20 seconds without dozing. Is that too much??

Kindly advise me whether this modification should be made or not. Has anyone performed this kind of modification on his GT (Frame9E with MarkIV control)?
We will certainly ask OEM before any such modification but I just want to know your opinion on that.

What was GEs response? you looking to upgrade your MKIV to something more modern such as the MKVIe?