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Manoj, This only occurs on one of several gas turbines? Or on all the gas turbines (how many does the site have)? And, after the off-line compressor water wash the problem doesn't occur? Does that mean you have tried shutting the unit down the same way as before the wash immediately after...

>Please help me out with the best answer. What is the context of the question? Is it being considered to operate the evaporative coolers at IGV angles less than 70 DGA?

Most GE-design Frame <b>5</b> heavy duty gas turbines have the Young & Franklin Hydraulic Ratchet Self-Sequencer, which controls most of the ratchet operation, but still relies on the turbine control system (Mark VI; Mark V; Mark IV; Mark VIe; etc.) to initiate the cycle. AND, the local...

Thanks for the feedback!

NGDave, <i><b>In general,</i></b> the HMI does NO control or protection functions--so even if it is having memory issues, all that should do is prevent viewing/monitoring unit operation, prevent sending commands, and prevent seeing alarms and events being sent from the Mark VI controller(s)...

davidmcc, It's not clear how the oil could change specifications. Do you mean it has suddenly developed a bad pH, or the total dissolved solids suddenly changed, or something like that? While it's common for there to be a slight increase in bearing metal temperature when vibrations...

CTLP, Yes. Compressor cleanliness, or, rather, the lack of compressor cleanliness, is one of the biggest contributors to loss of efficiency at Base Load. The next biggest contributor to loss of CPD is inaccurately calibrated IGV LVDTs. I continually find IGV LVDT calibration to be very...

Aptx4869, This forum is primarily for controls-related issues. Controls often includes field devices and instruments (solenoids; valves; fans; etc.), but this is pretty far off.

Aptx4869, Thanks VERY MUCH for the feedback!

There are probably several reasons. The reason(s) may be listed/described in either or both of the System Description in the Operations and Service Manuals and/or the Control Specification (probably Sect. 06). My best guess is that Inlet Bleed Heat starts operating as the IGVs close below 70...

abdi, The reason the OEM doesn't provide such valves is that it's entirely too easy for them to be left in the wrong position, or to be moved to the wrong position during turbine operation. There would have to be limit switches to check the valves were in the proper position prior to a start...

<i><b>In general,</i></b> the steam turbine in a combined cycle power plant is operated in a condition that just opens the control valve(s) wide open and the load is a function of steam production. And steam production is a function of exhaust gas temperature and flow, and most GE-design heavy...

Yes, it's possible and very likely. You can use the Marx V Alarm Drop Number and the ALARM.DAT file to determine the CSP signal that caused the alarm and the trip, and then use Dynamic Rung Display to verify the B-N Danger relay output does indeed trip the turbine. This should also be visible...

>I have 6-8 Mark VIe I/O packs but no control system. How do >i check or test if they work fine? Any easy methods? Easy? No. I/O Packs without terminal boards and at least one processor module would be virtually impossible to test. You could probably apply 28 VDC and connect a Ethernet cable...

mechnub, I have probably been misunderstanding the query; correct me if I am wrong. You and your colleague are saying that the cooling water jacket, which is welded to the outside face of the aft support leg, is bulging when the cooling eater system is pressurized. And, when the cooling water...

Have you looked-up the Diagnostic Alarm codes in the Mark VI System Guide, GEH-6421? What do they mean? What have you done to try to understand and resolve the problem? I don't have access to GEH-6421at this writing, but that's the proper way to troubleshoot and resolve the issue. Please...

Dual fuel systems--<b>particularly</b> on GE-design F-class machines--are an engineering work-in-progress. Studying the P&IDS and reviewing the physical layout of the systems (multiple systems) involved--AND the sheer number of devices and components should just re-enforce the concept of an...

Wajid29, There are at least two possible options. One, change the regulator type to a position loop, download the configuration change, and then use the Manual positioning feature of AutoCalibrate. Using this method without actual LVDTs, when you input any position the valve will travel full...

mechnub, It is not normal for aft support legs to experience "bulging." It is very difficult to imagine how a solid piece of steel (which is what all GE-design heavy duty gas turbine aft support legs I have ever seen are made of) could develop a bulge. The aft support legs I have seen...

So, this topic has come up before on control.com: http://control.com/thread/1476084329 (Found using the cleverly hidden 'Search' feature of control.com and the search term: +"turbine support leg" ... ) Shutting off the cooling water circulation prematurely sounds like that's the root...