Thread Starter


After general overhaul of the PGT10 A / 2 turbine, a start is made but a fault is displayed GGIDELFLT_H between the READY FOR LOAD sequence step and the CHARGE sequence step.

What does this defect mean and what is the remedy for the machine to start?
We <i>presume</i> the unit has a Mark V, Mark VI or Mark VIe--but we're not certain.

Is this alarm a Process Alarm, or a Diagnostic Alarm?

I <i>presume</i> the alarm text message is GG <b>IDLE</b>FAULT_H (a spelling error either by the control system programmer on the alarm text message, or the original poster in writing this post).

What have you done to troubleshoot this alarm (in addition to initiating multiple STARTS after clicking on MASTER RESET multiple times), and--most importantly--what were the results?

If the control system is a Mark V, Mark VI, or Mark VIe, what are all the alarms (Process <b>and</b> Diagnostic) present at the time of the START, and what alarms (Process <b>and</b> Diagnostic) are annunciated during the START up to the time of this alarm?

Alarms are very important to the troubleshooting process. Process Alarms, AND Diagnostic Alarms.

I'm going to presume the _H has something to do with the high-pressure turbine shaft (the Gas Generator (GG)) shaft, and possibly with the speed pick-ups. Have you checked the gaps of the GG (HP) shaft speed pick-ups? If so, what were the results?

Have you checked the wiring and terminations of all the GG (HP) shaft speed pick-up circuits--from the speed pick-ups to the Mark*? If so, what were the results?

Are you certain the shield drain wires of the GG (HP) shaft speed pick-up cables are properly terminated? If so, what were the results?

Again, this is all presuming the turbine has a GE Mark* turbine control system (Mark V, Mark VI or Mark VIe)--which annunciates Process Alarms and Diagnostic Alarms. And, without being able to see the control sequence program or the application running in the Mark* we can't tell you precisely what causes this alarm--BUT, if you can provide some information we might be able to help you.

What kind of control system is in use on the PGT10 A / 2 turbine?

What is the GG (HP) shaft speed signal? (The pre-voted speed signal, for all the speed pick-ups)?

Presuming the Mark* uses a <P> or PPROs for emergency electronic overspeed protection, what are the values of GG (HP) shaft speed signals for the emergency protective processors (TCEAs for a Mark V; VPROs for a Mark VI; PPROs for a Mark VIe (the Mark VIe might use SIL-rated processors for the emergency overspeed protection, but you should still be able to see the values of GG (HP) speed for the SIL processors)?

What alarms (Process- & Diagnostic Alarms) are present and active at the time of the START?

What alarms are annunciated during the START (Process- & Diagnostic Alarms)?

What have you done to try to troubleshoot the problem?

What were the results of your troubleshooting efforts?

Help us so we can help you!
<b>Moderator's Note:</b> This message came in as a separate post. It appears to be a response to CSA's post on this thread.

To keep the machine running, the critical signal (signal driving ESD: NGGIDLEFLT_H) was forced to ZERO for one minute in the TOOLBOX during the startup HP=80%.
Cabling ok.
speed loop ok.
Shield wires speed sensors ok.

Current situation of the machine: machine running. But if we want to shutdown and restart the machine, the critical problem NGGIDLEFLT_H will appear again.

for more details (photos) please send me your email so i can share with you the HMI pictures during the startup and emergency shutdown.
Hello sir,

I am the colleague of Mr.smailrth.

I am going to give you some details, so it may helps you to understand the problem.

Be informed that our gas turbine was in an overhaul. We have been changed the GG.
Our control system is MARK VI SIMPLEX without VPRO.
We have checked all the instruments installed in the GG; we found everything is working well.
Before starting the machine, no alarms appears in the cimplicity. After starting the turbine, the GG speed increases gradually from (crank.. ignition..acceleration). At the beginning of the load step HP SPEED: 91% (9875rpm), BP: 64% (5120rpm), when we start increasing the speed, a trip alarm appears (GGIDLEFLT_H) and an emergency shutdown occurs.

In the second attempt, we have tried to not to increase the speed during the load phase. An alarm appeared (GG Min speed time exceeded) and turbine tripped again.

After checking the manual of the gas turbine, we have got a doubt in the performance of GG.

Kindly regards

Thank you for the information and the details.

Yes; it would seem something is amiss with the gas generator. Many aircraft derivative engines have a gearbox that controls the angle(s) of the stator vanes and the IGVs. (I'm presuming the gas generator of a PGT10 has one or more rows of variable stator vanes, and IGVs.) If that's the case, then the Mark VI is most likely not the problem--it's something wrong with how the gear box configuration, which usually has nothing to do with how the gear box works. The Mark VI is just reporting a problem with the operation of the gas generator.

Has anyone used the Alarm List in Toolbox to troubleshoot the alarm? I believe if you double-click on the line the alarm appear on Toolbox will automatically jump to the appropriate function block diagram for the alarm.

Please let us know what you find.
Hi again,

Using the TOOLBOX To troubleshoot the alarm didn't help us too much, because most of the signals used in that LOOP are not defined.

What i understand from the loop, is that the Mark VI is controlling the increasing of GG speed By three Timers (DI:250: Dly=1750),
(DI:260: Dly=1375) and (DT:240: Dly=4). If the delay is done and the GG speed didn't attempt, a trip occurs.

After checking the manual of the gas turbine, we have got a doubt in the performance of GG.

Good morning

I have checked another program of pgt10 (same gas turbine) for another pump station. 

I found that there's a different value in the constant (check the attached picture) .

<b>Moderator&#8217;s note:</b> You cannot post illustrations to messages. Please post your picture to a download site.

Our program: KIDLCTM10A = 1750 scans.

The other station: KIDLCTM10A = 3500 scans.

What do you think?

Be informed that our PGT10  was shutdown for a long period (8 months). I noticed also that the time and the date is not synchronized in the HMI. (maybe it losts some parameters during the long shut down).

I look forward to hearing from soon.