We have upgraded the control system from Mark 2 to Mark 6e with frame 5b machine. We want to know the procedure to calibrate liquid fuel valve in frame 5b machine where there is no aux hyd oil pump. We went up to cranking speed and forced l4_xtp to false and l20flx1 to true, the turbine tripped. We repeated, but it happened to be the same. How to build up the pressure and proceed for calibration? I went through some threads but did not get the actual thing i wanted. In some thread it was given that give fire with ignitors off, but it will give fail to ignite and trip or come to crank speed.

Please help us with some procedure or ideas.

Thanks

 

Indoubt,

Does the liquid fuel valve have LVDTs?

Because one doesn't calibrate the valve, or the IGVs, or the SRV or the GCV. One only calibrates LVDT feedback.

Yes; you read that correctly: It's only possible to calibrate LVDT feedback from devices that have LVDTs.

Contrary to (extremely) popular and false belief, AutoCalibrate only calibrates LVDT feedback, not the valve or the IGVs. It's incorrect to say, "I want to calibrate the liquid fuel valve," even if the liquid fuel valve has LVDTs. Because one <b>isn't</b> calibrating the liquid fuel valve. One can only calibrate the LVDT feedback from a liquid fuel valve which has LVDTs.

Now, I'm not familiar with GE-design Frame 5B heavy duty gas turbines, unless you're talking about a two-shaft MS-5002B machine. Older GE-design Frame 5 heavy duty gas turbines used high-pressure liquid fuel pumps with variable swash plates to control the flow of liquid fuel; it wasn't a valve, but a variable flow-rate, positive displacement, axial piston high-pressure pump. If I recall correctly, these pumps had an RVDT (Rotary Variable Differential Transducer) which could be calibrated. Newer GE-design Frame 5 heavy duty gas turbines use a variable liquid fuel control valve--without LVDTs.

If the machine you're working on has an RVDT on the liquid fuel pump, it is possible to calibrate it, but it will take some doing. You should know that the calibration of the RVDT is not critical--it's basically just for position indication. Almost all GE-design heavy duty gas turbines which burn liquid fuel use feedback from the liquid fuel flow divider as the liquid fuel control feedback, and if they have LVDTs (or an RVDT) it's basically just for stability (for the larger Frame machines--and it's been eliminated from many of those as it's been deemed unnecessary) and valve position indication.

When you say the turbine tripped, what was the alarm text message for the trip?

Are you trying to use AutoCalibrate on the liquid fuel control valve LVDTs? Because, I believe that unless the Mark VIe regulator is configured for LVDTs (or RVDT) it won't allow AutoCalibrate to be used to stroke the device--because, again: It's not possible to calibrate a valve or the IGVs--it's only possible to calibrate the LVDT feedback (from a device which has LVDT (or RVDT) feedback).

l20flx1 only allows high-pressure hydraulic oil to open the Liquid Fuel Stop Valve, VS1-1. I've never seen a GE-design heavy duty gas turbine liquid fuel control valve that required Trip Oil pressure to operate the liquid fuel control valve--but that doesn't mean they don't exist.

So, please provide more information about the liquid fuel system on the turbine you are working on. Does it have a variable high-pressure liquid fuel pump with an RVDT, or does it have a liquid fuel control valve with LVDTs?

What is the Process Alarm text message that is annunciated when the turbine trips?

How do you calibrate LVDT feedback from other devices on the turbine with LVDTs without an Auxiliary (AC motor-driven) Hydraulic Pump?

Have you consulted the Control Specification-System Adjustment drawing from the Mark II to see how they described calibrating LVDT (or RVDT) feedback from the liquid fuel control valve/pump? Of course, the signal names will be slightly different, but the mechanical process would still be the same.

 

Indoubt,

While I can't help you with your calibration problem, those who can may need additional information. You say this is a "frame 5b" machine. Please confirm, that it is a 2-shaft (MS5002B), since a single shaft (5001B) is a really really old machine that would have probably had a link and levers control system when shipped. Assuming it is a 5002B, it will have variable 2nd stage nozzles to control HP speed and will have variable inlet guide vanes which may have been either modulating or open-close type. I am surprised this machine does not have an aux. hydraulic oil pump - the MS5002 machines I worked on did.

Since you have upgraded a Mark II Speedtronic to Mark VIe, please confirm that the Mark VIe is a Simplex version rather than triple redundant version. (I doubt that you would have added all the extra sensors required to do a triple redundant control.)