Can't Finish Start-up Sequence on GE Frame 5


Thread Starter



during start up of GE frame 5 ms 5002c, the start up sequence stop at 93% hp speed and can't reach 95% to stop bleed valves and auxiliaries of start up. we noticed that FSR value taking start up value which is the min selection value rather than acceleration value which was min and used during warm up. when the acceleration value become greater than the start up value by 0.2 which is sufficient to make the turbine reach 95% to complete sequence and start loading FSR get trapped by start up value.
What Speedtronic is this? MKV? When you are at 93% speed, what is controlling FSR, Startup,Speed, Temperature? Can you show a Startup curve or data showing Speed (HP & LP),FSR and Temp. during Startup, this would really help.

When did this problem start? Any maintenance done? Any changes made?
Thank you for your reply.

Speedtronic is MKVI.

At 93% speed controlling FSR is startup but it is acceleration controlling just below 93% with value lower than startup value that make FSR select min value then FSR locked with startup which has now the min value at 93% (31) while acceleration (31.2)

The problem starts after routine preventive maintenance on turbine
I will make a trend of startup parameters you mentioned but till I prepare it is there any transmitter need to be checked that may be involved in this problem

Best regards.
Natgasman has sent me a lot of data directly and I have made some comments. They have made some checks yesterday and were going to re-start the machine.

Sometimes it's difficult to post all of this big data to for everyone to see.

What I will do is try to summarize the whole problem here if and when we get a resolution. CSA, if you want to see the data, drop me an email to [email protected]

For everyone, this is an MS5002 which only makes about 90% HP speed on startup and LP only 45% speed abd hangs there. Looks like something is limiting FSR or maybe an SRV/P2 pressure problem.

To Forum Moderator - It would be nice if would give us a way to post data attachments, it would make analysis of these kind of problems so much easier and allow everyone to see.
Hello every one,

i am not specialist in GT. i am just a operation supervisor.

I want to give Some NOTES (MS5002C). if i am wrong please tell me:

- at 70% HP Speed the starting means stopped and the FSR switches from FSRSU To FSRACC

- At 87% HP speed (TNH)
* Exhaust temp (EGT) at max value
* IGV begin to open
* LP Speed at 45% speed

- between 88% and 95%(TNH)
* EGT Decrease than
* IGV Still open gradually
* FSRACC increase gradually

- at 95% TNH (FSNLfull speed no load)
* LP speed at 60%
* FSRACC Switches to FSRN
* Bleed valve closed + QA and HQ Stopped
* EGV at max value and begin to decrease
* HP Speed decrease than return to first 95%

- at 99% TNH
* NOZZLE beginning to close
* IGV near full open position
* FSRN still increase gradually

-at nozzle temperature control limit
* nozzle at min open position
* IGV full open position
* HP speed 100%
* LP speed at LP set point
* GT complete sequence

I think the problem is in the IGV's or Exhaust temperature.
please give as more details about FSR control, CPD, P2, IGV Position and Exhaust TEMP trend.

HOPE this help you
best regards
> Hello

Since this was a routine service nothing much should have changed.

I would take a closer look at the speed pickups. Just putting a wrench or fiddling with their wiring can cause their gains to change if they had marginal tolerances to begin with. And especially, when connected to MKVI/MKVIe modules where signal fidelity is unlike previous systems.

Where any of the LVDTs "calibrated" during the "routine preventive maintenance?" If so, has anyone compared the before- and after calibration values to determine if there are any discrepancies?

What Process- and Diagnostic Alarms are present during acceleration and when the speed hangs?

Is the nozzle actuator working properly? Was any work done to the nozzle ring during the "routine preventive maintenance?"

Were any of the servo-valves replaced during the "routine preventive maintenance?"

the whole problem revolves around FSRACCEL taking control of FSR around 85% HP speed and becoming the minimum value. The HP eventually settles around 92% speed and hangs there. We have pretty well come to this conclusion by studying a few start-ups from the trouble machine vs it's sister machine which is OK.

They are going to have a more intensive look at FSRACCEL to try and see what is causing the problem and making it limit the FSR, maybe a speed pick-up but I doubt it.

Trouble-shooting can be fun, this has been a nasty one!
glenmorangie and natgasman,

I haven't had the pleasure of working with a 5002C, but if memory serves correctly from other two-shaft applications I have worked on FSRACC is related to the difference between THNAR (the Acceleration Speed Reference) and the actual Acceleration (TNHA). I don't recall where the LP speed control came into effect but I don't think it's until after the HP is closer to rated speed (perhaps 95% for 5002Cs?).

My question about second-stage nozzle actuation stems from wondering if there's not enough energy being sent to the LP causing the HP to accelerate too quickly, limiting FSRACC. If the nozzles aren't moving correctly and aren't allowing enough energy to get to the LP then it would seem the HP would accelerate more than desired and the LP wouldn't.

I'm presuming the 5002C uses variable second-stage nozzles.... Perhaps I'm wrong; I have been before, and will be again in the future, too!

Is the load on the LP somehow different than it was before? Is it possible to uncouple the load from the LP and see what effect that has on operation? (As is typically done when performing an LP overspeed.)

Could the fuel have changed significantly recently? Because, if the FSR Control Constants haven't been changed since the unit was working correctly, then something like this could be causing a problem--though it would seem it would show up on the other machines, as well. That's also why I was asking what was done during the "routine preventive maintenance" to try to understand what could be causing the problem.

Were the fuel nozzles changed?

Is P2 pressure following the proper relationship? Is the SRV full open, or nearly full open to maintain P2 pressure during acceleration?

I'm just trying to offer other possible suggestions, and to follow along. (I haven't had to opportunity to download any Trend files and analyze them, and without being able to see the application code running in the Mark VI it would be difficult anyway.)

Again, just trying to help--and to keep up with the progress.

we have experienced to this problem many times in our site, with frame 5 C & D model. usually we found a fuel gas problem. the pressure looks ok but the the flow was not ok. try to inspect the strainer upstream the SRV, GCV block valves. also if you have a control valve in the line try to clean it, also you can run the cleaner of the inlet filer of the air intake.

if this does not work I have an other plan, by changing some constants in the control constants file.

We've been suggesting to look at a possible gas fuel flow restriction somewhere upstream of the SRV/GCV but we haven't heard anything back about any checks that have been done.

In my experience, if there is a flow restriction it shows up primarily as a very high opening of the SRV--sometimes 100%. This is because the SRV is having to open excessively to maintain actual P2 pressure equal to P2 pressure reference. But, again, we've heard nothing about a problem with SRV position or P2 pressure.

But, if the SRV were not going full open and there was a restriction of gas fuel flow upstream of the SRV, then the GCV would have to open "excessively" when on speed control--but it's not clear if it's on speed control (usually LP speed control for two-shaft machines) or on acceleration control. And, if the GCV position is excessive then it's possible start-up acceleration control is falsely limiting FSR--because there isn't enough fuel flow to support acceleration.

Hopefully we'll hear more soon!

you are right, if the machine is loaded, and you can see the GCV, SRV opening higher than the FSR acceleration limit FSKSU_IA. but when the machine is too close to L3 complete sequence, your HP and LP speed if it's two shaft machine are very close to the HP and LP threshold.

these usually happen when you do a maintenance for the machine (HGPI, MI,..), or when you fuel gas valves are not well calibrated, the position feedback is less than the required position, or if the fuel gas filter are dirty, or the inlet air intake are not clean.

usually what we do, just increasing 1% or 2% in the fuel gas by changing the FSR constant for the acceleration limitation.

Hopefully this will help!