Hi everybody,

Our gaz turbine (9001E) tripped by loss of flame two times at 25MW.
We suspected at first the servo valve (65FP) and
we changed it by a new one.

After the second test the turbine was fine, but many hours of work it retripped at 50 MW by the same cause (loss of flame).

We already launched a trend to troubleshoot the case. Some one of GE recommend to change the Liquid Fuel Stop Valve Limit Switch (33fl) (I wasn't there so I don't know why) and they changed it.

At the third test it seemed good but after many hours of working it retripped again at 90MW.

By checking the second trend (90MW trip), I observed that:
-33FL toggled "from false to true" at the same time with [< fqrout "from 66 to -25%"
<Liquid Fuel Stop Valve Control Signal Time Delayed "from true to false" at (12:58:41.7)
but the Master protective signal toggled (L4) toggled "from true to false" at 12:58:42.1,.

Can what happened be due to a problem in the stop valve (VS1)? or to the new 33FL? (we make also in the trend signal of battery ground and +/-Leg 125VDC Bus Level and +&- 125VDC Ground but there were some smal fluctuation just after the trip.

-I need your help to resolve this problem.
-I don't know what's the role of l20FLXX can you explain to me?

Best regards

 

Hai,

L20FL1X for liquid fuel trip oil, if it de-energized during GT unit running. Unit will trip immediately. So please look, is there any ground fault on the solenoid valve 20FL? and check the coil resistance.

Liquid fuel stop valve VS1 may have two limit switch 33FL1C and 33FL1O, check these two are working normal.

Take care
G.Rajesh

 

A loss of flame trip in a GE-design heavy duty gas turbine with a Speedtronic turbine control system means that flame was lost before any other trip condition was detected. So a liquid fuel stop valve that closes unexpectedly is certainly a possible cause.

We can't know what l20flxx does without being able to examine the application code and wiring drawings of your unit. Typically, l20fl1x is used as the logic signal driving the PTRs (Primary Trip Relays) of the trip solenoid circuit. There have been auxiliary fuel stop valves (usually upstream of VS1-1) driven by a logic signal called l20flxx, but that's not a certainty that you have the same or even a similar application and configuration.

The other possibility is that there is something in the ETR (Emergency Trip Circuit) that is causing VS1-1 to close. Have a look at the TREG and VPRO configurations. There should be Process Alarms for all the E-stop P/Bs and any trip inputs connected to the TREG. But, sometimes (far too often, actually) someone forgets to put a process alarm on a trip input to the TREG.

You also haven't told us what Diagnostic Alarms are present on the unit while it's running and immediately prior to and after the loss of flame event.

Write back to let us know what you find.

 

Thank you for replying to this thread:

Dear Mr G.Rajesh, thank you for the information about l20FL1X but I still have problem with L20FLXX which is described by (Liquid Fuel Stop Valve Control Signal Time Delayed).

-We have only one limit switch (33FLC) and it's changed by a new one.

-No ground fault on solenoid 20FL and I just measured the coil resistance, it's 607 ohms (I verified the coil resistance of other GT I found 624 ohms.

Dear Mr CSA,
>.....So a liquid fuel stop valve that closes unexpectedly is certainly a possible cause.

-Depending to the last test (GT tripped at 22:40:40) & its trend, what you say is confirmed buy th behavior of the 33FL wich toggled two times before the trip (at .2 secs).

-I checked the TREG and I found these alams:
at 21:09 "" solenoid voltage 2 does not match command state [ppro-ca001-1C4A drop 28 pack R (and the same for S and T)
With a double clic we get:

__PPRO Diagnostic Alarm 99-101 Solenoid Voltage [ ]does not match commanded state

Cause: The solenoid voltage associated with K1-K3 does not match the commanded state. K1-K3 are closed, but no voltage is detected on the solenoid.

Solution: This may be due to removal of solenoid voltage through another means when the I/O pack expects to see it. Review the system-level trip circuit wiring and confirm the the voltage should be present if the I/O pack energizes the associated trip relay.

As I said the trip was at 22:40:40 and after 3 sec we get an alarm:
__JPDF- 1 DC 125V Ground magnitude (JD1/JZ2/JZ3 connector) out of range.

I don't know what's the reason of that, but the help says:

PPDA Diagnostic Alarm 113, 115
JPDF-[ ] DC 125V Ground magnitude (JD1/JZ2/JZ3 connector) out of range
Cause: The 125 V ground feedback magnitude is greater than Gnd_Mag_Trig_Volt.
Gnd_Mag_Trig_Volt is set too low.
One side of the dc 125 V source voltage is grounded.

Solution: Verify that Gnd_Mag_Trig_Volt is set correctly.
Check the connections to the specified connector.
Verify the grounding of the dc input signals. Refer to the JPDF help documentation.

If DC 125V input is not used, this diagnostic alarm can be disabled by setting the InputDiagEnab parameter on the associated input (DC_125VFdbkMag) to Disabled.

No battery ground is detected after the trip.
Mark 6e control system.

Thank you very much and my best regards.

 

Hello, do you know how Gnd_Mag_Trig_Volt is calculated by the firmware?

 

@SuperNovaCTRL,

WHAT does your question have to do with Loss of Flame Trips?

What turbine control system are you working on?

What is the signal Gnd_Mag_Trig_Volt used for?

What machine are you working on?

What is the problem you are experiencing and how did you arrive at the conclusion it is related to Gnd_Mag_Trig_Volt?

What have you done to troubleshoot the problem--and MOST IMPORTANTLY: What were the results of the troubleshooting (other than the problem isn't resolved)?

If you are working on a GE Mark* turbine control system, what I/O card or I/O Pack is this signal associated with?

If you are working on a GE Mark* turbine control system, what are the Diagnostic Alarms for the I/O card or I/O Pack associated with this signal?

Help us to help you.

 

@WTF?
if you read the last message on the thread by controman, you will see that "Gnd_Mag_Trig_Volt" is part of the solution provided from his help support.
I am working on exact same machine and HW of the one above.

quote
""
Solution: Verify that Gnd_Mag_Trig_Volt is set correctly.
""
unquote

 

@SuperNovaCTRL,

Kudos for using the Search feature.

Sorry if I offended you; that wasn't the intent. The original post was from 2011. The last reply was 25 Dec 2011. Do I read the entire post after reading a new response to that post? No. We get a LOT of posters here who don't know how or don't want to open a new thread; they find a thread that seems to fit their need and they add their problem/issue to it and we don't know what they're asking or why. Your post (from 2023) doesn't tell us you are working on the same problem, on the same Frame size machine, or the "same" turbine control system.

I don't have access to Toolbox or ToolboxST at this time (nor when you posted) but from my experience with GE manuals when they suggest to check if something is set correctly they mean there is some value (possibly field-adjustable, like a Control Constant, but probably an I/O Configuration Constant that is field-adjustable) that may have gotten tweaked, inadvertently, of course.

It's rare for firmware calculations to be found anywhere, even in a GE manual. (An exception to that is generator synchronization parameters are often well described, including how some are to be calculated.)

The appropriate GE manual (we don't know if you're working on a Mark* VI or Mark* VIe) would be found probably in Vol. II of the Mark* VI/VIe System Guide for the version of the Mark* you are working on. You can do what @controman most likely did--use the Diagnostic Alarm Drop Number and go to the appropriate section of the manual and look up what GE suggests for troubleshooting, and by reading a little before or a little after you might find some useful information (maybe).

So, just because you responded to a 12 year-old thread that just so happens to very closely describe your problem doesn't mean we know what your problem is and what machine/control system you are working on. We strive very hard to be as helpful as we can but there are limits to our intuition and telepathic abilities.

In my experience, the 125 VDC battery is pretty well isolated from flame detector power supplies--the 125 VDC is inverted to AC and transformed up to some value that, when converted to AC provides the 335 VDC power supply for the Geiger-Mueller style flame detectors. BUT, GE and its packagers don't always use Geiger-Mueller flame detectors with Mark* VI/VIe turbine control systems. Very often, they use 4-20 mA two-wire flame sensors, and those are even more isolated from the 125 VDC battery so that even a HARD ground won't cause flame detector/sensor issues.

IF the fuel stop solenoid is powered by 125 VDC, a ground (or multiple grounds) on either leg of the 125 VDC supply won't cause the stop valve solenoid to not operate properly. (Any number of grounds on the 125 VDC battery supply on either leg of the 125 VDC battery supply won't cause the stop valve solenoid to not operate correctly. BUT, if there IS a ground (or multiple grounds) on one leg of the 125 VDC battery supply AND a ground develops on the other leg of the 125 VDC battery supply--THAT will wreak havoc on the entire Mark* turbine control system, not just the fuel stop valve solenoid.

As CSA wrote: "A loss of flame trip in a GE-design heavy duty gas turbine with a Speedtronic turbine control system means that flame was lost before any other trip condition was detected." In other words, the Mark* didn't detect any condition that should have resulted in a trip from the turbine control system before flame was lost. THAT can be a LOT of issues, but most likely NOT a 125 VDC battery supply ground. (We don't know what Diagnostic Alarms you are seeing, and what is happening with the machine prior to the trip--but we have asked!)

Help us to help you! And try to understand what we might and might not be capable of intuiting from anyone's (including your) post.