We have GE Fr.5 Mk6 control system. frequently the VCMI card failure error appears and gets reset automatically or thru RESET push button on the card. turbine continues to run with several diagnostics alarm on the screen. what could be the reason for this?

 

If you want to get to the bottom of what's causing the failure and the Diagnostic Alarms, YOU NEED TO TROUBLESHOOT AND RESOLVE THE DIAGNOSTIC ALARMS.

Post the Diagnostic Alarms and maybe someone can help, but don't just tell us you reset the card and there's still some Diag. Alarms and ask us why without telling us what the Diagnostic Alarms are.

 

Dear Khan
Please post the diagnostics alarms.

 

Dear CSA and All,

I would like to focus the following diagnostic and process alarms appearing along with the momentarily failure of VCMI card{GE Fr5 Mk 6 control}during turbine running in GAS fuel mode.

1. slot1 VCMI diag. alarm for R-S-T controller.

2.DC power supply under voltage alarm

3.Exhaust TC card communication fault

4.Battery 125 V DC ground alarm

5.compressor inlet thermocouple disagree

These alarms got reset by activating Diagnostic RESET and Master Reset buttons on HMI. The above mentioned alarms appears once in a month occasionally and resets as I have mentioned. My interest to know is as to what causes, the process alarm at point 2 to 5 to appear along with the status failure of VCMI. Pls help to diagnose these alarms.

Thanx..

 

What have you done to try to troubleshoot and resolve the alarms?

The two alarms that should be of most concern to you are the DC supply undervoltage and the 125 VDC battery ground alarm. They are likely the source of most of the other alarms.

The Mark VI System Guide, GEH-6421, lists the limits of DC supply voltage "excursions" in the manual; I believe they are generally 90-140 VDC. If the power drops too low, then the power supplies will actually shut themselves off to protect themselves and the unit from a low voltage condition.

A "severe" battery ground can also cause an undervoltage condition under certain circumstances.

And without voltage or with low voltage, the Mark VI can't do it's job very well.

So, find and fix your grounds and investigate and resolve any voltage supply issues and you will likely resolve all the alarms in the list.

One thing to note is that if the Mark VI is also being powered through one or more <DACA>s, they are <b>NOT</b> filters and will generally pass any spikes or noise along to the Mark VI. Many a nuisance problem has been caused by poor AC power supply to the <DACA>, and from switching power on an off to the <DACA> during operation, either intentionally or unintentionally.

Lest you or anyone think that the <CPF> (Conditioning Power Filter) filters provided with most Mark VI turbine control panels will provide protection against most input power supply problems, they won't. They are minimal protection and generally are there to try to prevent electrical noise from getting out of the Mark VI panel and onto power supply system/wiring. Many sites I have visited with issues similar to yours have had failed <CPF> components caused by voltage spikes or dips.

But in my personal experience, the fact that you listed both 125 VDC undervoltage and 125 VDC battery ground alarms indicates there is something very wrong with some wiring and that is likely the source of the other alarms you list.

Another problem source is AC induced on the DC wiring of the Mark VI. Improper signal level separation (cable segregation) is also a very big cause of these kinds of alarms, as is a bad battery charger output (failing or failed output filter capacitors).

Something else that many people have have tried is running the Mark VI with only a batter charger output, that is, without the battery. Not only is this extremely dangerous from many perspectives, the battery charger expects the battery to be present and to "assist" with filtering the charger output to a certain degree. So, powering the Mark VI with the charger without a battery can be very damaging to the Mark VI power supplies. Even if it was only done once during commissioning for a few days or weeks.

Lastly, cycling power to the Mark VI by opening and closing the DC (and AC) power supply breakers only (without using the switches in the <PD> power distribution core) can also cause lots of issues for the Mark VI power supplies.

These are industrial pieces of equipment, but that doesn't mean that one can treat them like they are military-grade and are bullet-proof. They're not consumer grade, but they do need to be operated and maintained with some degree of care.

Which includes keeping them free of grounds, and supplying a clean, regulated power source (or sources, as the case may be).