We are facing VCMI card related problem frequently in our GT-1 machine. Give us advice to resolve this type of problem permanently. The problems are described as below

On 27/11/2011 night at 9.30 pm GT1 Trip on "GCV NOT FOLLOWING REF. TRIP" before few second one diagnostic alarm came i.e "P 428 (Y) XVPROS8S02_A DIGNOSTIC ALARM" on hmi. After that we make master reset , at zero speed of turbine ready to start came so machine started.

At on 28/11/2011 morning at approx 9.30 am machine trip on same alarm as above. we observed GCV ref and position having 10 difference. so we are trying to calibarate GCV as per manual 2 procedure.

But in that Min pos and MAX pos is done and fix it. After that push calibrate button but GCV is not open/close automatically. so, we are taking shutdown of G1 mark vi. and restart it but all 3 processor showing BOOT mode only and at mark vi all processor GREEN led blink at a time.

Then we check diagnostic alarm in VCMI card in m6b file. we found in T rack VCMI card having fault code 46,50 persist with 1 state. so we swap the T rack vcmi card with S rack. so diagnostic alarm of T rack reset and set in S rack. so we concluded that VCMI card of T rack was faulty. so we replace T rack card with new one on dated 08/12/2011.and in S rack original card insert.

T rack download configuration and reboot all processor. so VCMI diagnostic was reset. and all three controller come out form boot mode to normal. m6b file sho was equal and normal.

1) so we start GT, it was running normal with no fault code in VCMI card.

2) After two days on dated 11/12/2011, again problem was observed in “S” processor with VCMI card diagnostic alarm having fault code 47, 51 in m6b file. But machine was running normal with VCMI fault code.

3) On dated 20/12/2011 evening machine was trip on "GCV not following ref. trip" After zero speed we check the VCMI diagnostic alarm was reset. We check in all. VCMI card having no diagnostic alarm in m6b file. In field LED status of all VCMI card was found OK. So we start the machine and take the load on machine.

4) From 20/12/2011 evening to 24/01/2012 morning GT-1 machine was running normal without any diagnostic alarm in all three VCMI card.

5) on 24/01/2012 morning 8.34 AM the VCMI diagnostic alarm was observed in “S” processor with fault code 47,51 in m6b file. M6b file showing equal.

6) so we take the shutdown the machine and power off the "s" rack power. Take out VCMI card and cleaning the card and its slot. After that re-insert the card and power on. VCMI alarm get reseted. so we start the machine on 29/01/2012.

7) again on 04/02/2012 00.00 hrs VCMI "s" diagnostic alarm came and automatically reset. At 2.30am same alarm came and machine was trip on "GCV NOT FOLLOWING REF."

Still VCMI "S" diagnostic alarm persist. Its fault code was 47,51.

We observed that whenever VCMI diagnostic alarm was persist, after few days the machine was trip on "GCV NOT FOLLOWING REF. TRIP".

 

Hi,

On TMR control system, even serious defect on one processor should not trip the turbine. So it seems that you have two independent issues:

1. communication problem with VCMI cards - this can provoke a trip only if two cards at the same time do not communicate and in this way are lost control data
2. GCV valve issue

The alarm: "GCV NOT FOLLOWING REF. TRIP" comes when actual valve position differs from the requested position by 5% (+5sec time delay).
You stated that valve was recalibrated. Did you check during valve calibration, that travel is smooth and that there are not areas with restrictions in valve travel.

When valve, during the service, operates all the time opened to the same level, on the surface of the cylinder of the actuator is created a groove. Finally groove is so dip that sealing ring on the piston can not pass through it what restricts the valve travel. It may happen that during valve calibration the issue was not noticed because valve travels fast. With turbine in service, valve travels slowly and piston can not pass through the defective area.
Defect can be diagnosed with turbine in service by monitoring the gas valve servocurrent: when piston of the actuator passes through the area with groove, servocurrent becomes much more negative than typical - typical is apr neg 2...3%.

During the valve calibration, by executing two steps: 'Position check' and 'Current check' this defect also can be observed.

If each time your turbine was tripped, GCV valve was opened to the same position or (if valve position was not recorded) turbine's load was similar - this could confirm the defect of the gas valve actuator.

Regards

 

Hi uj,

>Then we check diagnostic alarm in VCMI card in m6b file. we found in T rack VCMI card having fault code 46,50 persist with 1 state. so we swap the T
>rack vcmi card with S rack. so diagnostic alarm of T rack reset and set in S rack. so we concluded that VCMI card of T rack was faulty. so we replace
>T rack card with new one on dated 08/12/2011.and in S rack original card insert.

The fault code 46,50 in <T> VCMI card means that the <S> (NOT <T>) VCMI card has a communication failure (IONet-2 Communications Failure. Loss of communication). The possible reasons are Loose cable, rack power, or VCMI Problem...... I think you should replace the <S> VCMI card instead of <T> VCMI

>2) After two days on dated 11/12/2011,again problem was observed in "S" processor with VCMI card diagnostic alarm having fault code 47, 51 in m6b
>file. But machine was running normal with VCMI fault code.
>
......
>
>5) on 24/01/2012 morning 8.34 AM the VCMI diagnostic alarm was observed in “S” processor with fault code 47,51 in m6b file. M6b file showing equal.
>
......
>
>7) again on 04/02/2012 00.00 hrs VCMI "s" diagnostic alarm came and automatically reset. At 2.30am same alarm came and machine was trip on "GCV
>NOT FOLLOWING REF."
>
>Still VCMI "S" diagnostic alarm persist. Its Fault code was 47,51.


The fault code 47,51 in <S> VCMI card means that the <T>(NOT <S>) VCMI card has a communication failure(IONet-3).

I have just a few suggestions for your reference...

First, I suggest that you need to check all the IONET cable and terminal resistors, including <P>'s.

Second, may be the VME power supply voltage has some failure, so, the PDM voltage needs to be checked. check the all VME DC voltage in VCMI card in m6b. such as 5,15, focusing on 5V voltage.

Third, the <T> VCMI card card might have a problem....

good luck!

 

Good day friends,

We are facing VCMI card related communications problem in one of our Gas Turbines. It’s a GE FRAME 9E, with MARK VI controls system. The problem is described below.


The GT was on cool down mode and there was a power surge. Thereafter, the fault code 47,51 ( IONET - 3 communications failure) appeared in <R> , <S> and <T> VCMI cards. There was communication loss and the control room HMI is black. Controllers <R> , <S> in boot state and <T> is unknown.
I really would appreciate suggestions please.
Regards.