Dear Sirs,

I need to understand GE Frame machines (Mark VI) logics, which are in specific terms like L4, L86, etc, earlier i have operating experience with LM 6000 as well as alstom and siemens machines, they have kks system and defined commands for control valve, movs, pumps but in GE i am very much confused,

Any help in this subject will be appreciated.

 

Dear GTMAN,
GE uses the ANSI designation system, please refer to site http://www.kilowattclassroom.com/Archive/DevNos.pdf, this is one place I found the list, I am sure there are many others.

With each turbine package there should be an included "control specification" that lists all hardware devices included on the turbine, and lists most logic control algorithms in use. L4 stands for "logic master element". Signals generated in logic will almost always be preceded by "L", very similar to to a "DIC" digital input calculated, in Alstom/ABB logic. By referring to the ansi designation you will be able to understand where a signal is generated, or what it is driving.

GE uses many "macros" in logic, most of these are well explained by right clicking on the macro and choosing item help. I have found that I can understand GE logic somewhat easier than ABB etc, I think mainly because of time spent with it, as with anything else the more time you spend with something, the more comfortable you become!! Do yourself a favor and read any manuals/documentation you can find associated with your turbine, your confusion will quickly disappear.

 

Although I had worked extensively with DCS's and AB PLCs, I found MarkV difficult to follow and hard to learn until we brought in a GE instructor for a one week class.

The instructor did an excellent job, explaining how to interpret macros (or GE big blocks as they're called)--some of which don't appear in the documentation such as the BB that handles exhaust thermocouple spread fault detection and spread logic--the ANSI tagging system GE uses, where to find the documentation with copies of the PDFs, the architecture of the MarkV hardware and how TMR is implemented at the I/O board, processor and software levels, how to set up high speed data collection on the I and HMIs using the view2 program, and many other usefull things. He also teaches the MarkVI, Ve and VIe and I would recommend him to anyone who wants to learn these systems.

One week really wasn't enough to cover everything you need to know, but if you're motivated enough to self study, it will provide you with a very good foundation.

Management balked at the cost of on-site training because it is pretty expensive. However, based on my own greatly improved ability to troubleshoot the MarkVs, I know that it will result in reduced downtime and trips because it already has.

Within a week or so of the class, one of our 7FA's would not auto-sync. I wasn't very familiar with generator sync logic and the fairly complex breaker control circuits--I'm mainly I&c--but no one else was answering their phone on a Friday night before Christmas so it was up to me.

The alarm display indicated voter mismatches between the R,S and T cores along with the BREAKER FAILURE and other alarms. The voter mismatches seemed to indicate a possible MarkV hardware failure.

I from class that the P core monitors a single phase of generator and line side voltages, among other parameters. Its X, Y and Z cores determine if and when to close the breaker, energizing the 25, 25X and 25P relays at sync time. The voltages coming in to the P core were all good, so there were no problems with the PTs. The question then became, was the P core firing the sync relays?

Using the View2 program with the help of an online GE diagnostics support person, I was able to scan the "25" relay outputs and several other logic points (that she wanted to see) at the processor scan rate. We attempted to auto-sync again, and the data clearly showed that these relays had been fired for 4 processor cycles in an attempt to sync, but the breaker wasn't closing. The problem turned out to be a bad set of relay contacts in the breaker close coil circuit.

Now I'm installing the same view2 files on all our MarkV HMI's--it's the same DOS program used in the I's and I'm sure the MarkVI's have it or something similar--reducing troubleshooting time even further.

GE offers training for the MarkV's through VIe on-site and in Salem Virginia, but given a choice I would definitely go to Salem. It's cheaper, and they have full blown controllers set up to provide a more thorough hands on learning experience.

If your company doesn't understand that the training is actually a good investment, than you'll have to teach yourself through the GE documentation and that will take a lot more time.

I'm hoping some day that CSA will write and publish a book on the subject, but until then...