Mark VI system modules not communicating after shutdown

H

Thread Starter

H D DALSANIA

We are having a Mark Vie System for our gas turbine (S/N: 296462, Frame VI machine) control and was commissioned in Feb.2012. The Mark-Vie system FDM No.: F705G1.

Recently our GT was in shutdown and Mark-VIe panel was powered off for Shutdown activities in the field for about two days. Before switching off the power to MK-VIe system it was health and there were no problems in the system.

But on 27/10/2013 at around 6:30pm when it was switched on following problems observed.

(1) During startup <S> controllers could not booted for a long time. It is observed that it got booted after <T> Controller get booted and becomes healthy. It was taking more than 20 minutes or so to get booted after <T> controller becomes healthy.

(2) During and after complete booting of all three controllers it is observed that various PDIA 6 nos, PDOA 5 nos, PAIC 1 number, PPRO 1 number, PPDA 1 number etc are not communicating with controller. They are giving communication error. Remain in ‘Attn’ red LED blinking. Even one number controller UCSA not getting booting.

With this problem we could not start our machine and other start up activities.

It is our humble request to let me know the reasons of above mass failures at a time. Anybody have faced such failures?

We had to urgently procure and repalce the modules to start plant.

Kindly note that power supply, earthing system and power ON sequence are as per recommendations by OEM.

Such a big failure is very uncommon in GE system. Have anybody got repaired failed modules and got analysis reports for root cause analysis.

Kindly share your views, suggestions and experience.
 
You have a Frame <b>6B</b> with a Mark <b>VIe</b> turbine control system.

As you indicated, it's <b>NOT</b> typical for these many components to "fail"--and it's not clear that they did fail (from the information provided).

When you say you followed the OEM's "instructions" for powering-down and powering-up the Mark VIe, I would be very interested to know what publication they put those instructions in, because I have not seen such detailed instructions before from the OEM. So, if you could provide the publication number (such as, GEH-nnnn, or GHT-nnnnn (where "n" is a digit) that would be very helpful to a lot of people.

From the information provided, it's not clear exactly what work was done during the maintenance outage, or even why it was felt it was necessary to power-down the Mark VIe during the outage.

Even though the Mark VIe is powered-down, the field devices are STILL connected to the Mark VIe, and so if, for example, there was welding done in the vicinity of some field devices that could STILL cause damage--even though the Mark VIe was powered-down.

From the information provided, it's not clear what was done to troubleshoot the inability to re-establish "communications" with the Mark VIe components deemed to have "failed"--and it's also not clear why replacing them (if that is indeed what was done) suddenly resulted in their ability to communicate and to be able to re-start the turbine.

In general, when it's not possible for an IOPACK/terminal board combo to "communicate" with a UCSx (microprocessor), there is some problem with the IONET for that microprocessor. It's not clear from the information provided if any investigation was done to see if, for some reason, any IONET network switches were common to the "failed" processors and why the switch(es) might not be working--and, why they just started working after replacing all the "failed" components.

Simply powering-down a Speedtronic panel does not make it immune from unsafe field practices. And, there simply was not enough information provided to be able to say what might have been the problem, or what troubelshooting was done (other than a shotgun approach to replacing components) or why simply replacing the components would have caused them to all start "communicating" again. Something is just not adding up to a logical explanation.

Mark VIe components are powered by 28 VDC--from power supplies that convert 125 VDC, or 110/220 VAC, or in some cases 24 VDC, to 28 VDC. So, problems with the turbine control panel power source (125 VDC, 110/220 VAC, etc.) should NOT cause problems with Mark VIe components as the converters should provide some level of isolation from panel power supply problems.

However, if somehow high voltages (DC or AC) and/or currents were inadvertently applied to some field devices that share a COMMON then it's certainly possible that damage could occur. The Mark VIe is typically provided with two earth/ground connections--one for safety, and one for instrumentation. So, as long as this is recognized and taken into consideration in the field when performing maintenance and/or testing there should be no problem for Mark VIe components.

It is hoped you have returned your lot of "failed" components to the turbine packager and that they will provide you with some kind of failure analysis. If so, if you would please share the results with us when you receive them it would be greatly appreciated by many.

Again, without a LOT more information about the circumstances it's really not possible to say much about how so many Mark VIe components could have seemingly failed at "once." Something isn't known or hasn't been communicated or has been overlooked in the site investigation into what might have possible caused such a mass failure of Mark VIe components. I would be highly surprised if the failure analysis report from the packager indicated all or even most of the components had, indeed, actually failed. If it does indicate most or all of the components failed I would expect the packager, and GE, to be extremely interested in trying to understand <b>EXACTLY</b> transpired to have cause such a mass failure--because they certainly don't want the same thing to happen again.

Ever.
 
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