We have to commission a frame 5 gas turbine with mark VI controls. i would like to ask you if there are any problems we should look out for and rectify before start-up.

Also share any problems faced during its operation.

 

Could someone please tell me the differences between Mark VI and Mark VIe?

How much improvement from a customers point of view have they made?

Also anyone ever wonder why GE went from Mark VI to Mark VIe in just six years....
I mean they introduced a new product so quickly that it left me doubting the performance of Mark VI.

The problem is we have Mark VI on one of our new Gas Turbines (GE Frame 5) & i would like to learn from other peoples experiences.

Please put up your views on this matter.

Regards.

 

You don't have a problem because your turbine(s) have Mark VI, or even if they have Mark VIe. They're both going to do exactly the same thing, with almost exactly the same interfaces (HMIs; similar troubleshooting and configuration applications; etc.).

Mark VIe is a more compact version of Mark VI, that is simpler to produce and has some excellent expandability characteristics that the Mark VI lacks.

GE's Customers are always telling them that their products are too expensive. GE, as any manufacturer, is always looking to improve their products and reduce costs. The Mark VIe wasn't produced because of problems with the Mark VI; it's just the next generation of the Mark VI, which allows them to provide the same functionality in a different package with cost improvements due to technology that wasn't available or cost-effective at the time the Mark VI was developed.

I wonder about people who think that just because a manufacturer provides a newer, more capable version of their previous products that the manufacturer is covering up deficiencies or problems or trying to short-change their Customers. There are enough conspiracy theorists in the world as it is. Technology is changing at a very fast rate, for nearly everything; turbine control systems are not immune from this rate. The difference is likely that GE is investing money in developing newer versions of their turbine control systems faster than others. (There are many who believe that GE waited too long in developing the Mark VI to replace the Mark V!)

Many of the same terminal boards used with Mark VI are also used with Mark VIe. There are also a host of new, more compact (which is *not* necessarily better in many people's opinion) terminal boards which are being used.

In the Mark VI system, the terminal boards have to be connected to VME cards in large processor racks with cables that carry discrete and analog signals between the terminal boards and the VME cards in the racks.

In the Mark VIe, the terminal boards have I/O Packs installed on them (very often where the Mark VI cables used to be connected) that convert the discrete and analog signals to digital signals which are transmitted via the IONET to the main processors. The I/O Packs of the Mark VIe replace the `individual VME cards of the Mark VI. The I/O packs have LEDs for indication of the state of many signals, and in some cases the health of many signals.

The Mark VIe main processors are either VME-sized cards or even smaller, units which don't require large racks and power supplies and ventilation fans. These units take up much less space than the VME racks used for the Mark VI system.

The IONET is a proprietary, industrial Ethernet, which makes expanding capability by adding more cards for more functionality much easier. The IONET can be copper Ethernet or fiber optic Ethernet. It can also be redundant, with two IONET cables (Ethernet cables) for each I/O Pack.

I believe that GE are also looking at distributing the I/O, meaning that new, and hopefully retrofit, applications will be able to locate I/O terminal boards closer to the field devices and instruments and just use Ethernet cables to connect them to the main processors located in a control room.

The Mark VIe can be obtained in SIMPLEX as well as DUAL- and TMR redundant configurations for retrofit applications. Most new turbines are always supplied with TMR configurations. The DUAL redundant version claims not to be "hot standby", but the details are not very well documented.

The Mark VIe is configured and troubleshot using ToolboxST, which is similar to the Toolbox application used for Mark VI control systems. Not exactly the same, but similar.

The HMIs used for Mark VIe still (AARRGGHH!!!) use CIMPLICITY though. The Mark VIe HMIs run software which allows more direct communication with the Mark VIe and provides some new and useful functions, most notably for Alarm Management.

So, GE have leveraged their Mark VI product line by using existing I/O terminal boards for their newer Mark VIe product line. The Mark Vie uses smaller main processors, which are connected to the I/O Packs on the terminal boards via Ethernet, making expandability easier. It's also simpler to package the Mark VIe, which means it reduces the cost of the system which is what GE's Customers complain about most: cost.

The Mark VIe can also be purchased for systems requiring SIL rating (which in many people's minds is also *not* necessarily an improvement in control systems).

From a Customer's point of view, both control systems will monitor, control and protect turbines with almost no discernible difference. The biggest difference is in expandability. While the Mark VI is expandable, it's much more difficult to do so than with a Mark VIe. This is especially true for machines which are virtually "full" of I/O in their current configuration (such as many F-class units, especially those with dual fuel capability) and who want to add new options or functionality which would require more I/O capability. It's much more difficult to expand a Mark VI (it can be done) than it is to expand a Mark VIe.

The HMIs are slightly different, though both still use CIMPLICITY. Toolbox and ToolboxST both have Watch Windows, and very good trending capability.

I'm told GE have issued an end-of-production letter for Mark VI. Mark VIe is their control system going forward. There will probably still be a few Mark VI systems being shipped for a few more months.

To my mind, there's little difference between the systems. They even have some common components (I/O terminal boards). But, if I were specifying a turbine control system, I would definitely be asking for the newest version. If it were available. Depending on when your turbine was "ordered" and built, the Mark VIe might not have been available. Just because the Mark VIe is available now and you're receiving a Mark VI doesn't mean you have been shortchanged or are getting any less functionality. Many mobile phone manufacturers produce updated and upgraded versions of their phones and release them while there are still older models available.

 

> Could someone please tell me the differences between Mark VI and Mark VIe? <

The MKVI is a VME (Versa Modular Euro)large form factor type control system. It has proven to be a robust and reliable control system as a continuation from the early speedtronic control systems. It's main shortcoming in recent years is its inability to be a "distributed" control system. It made for a great turbine control system where the controller and I/O could be located in a central location, but was unable to compete with ABB, Emerson, Honeywell, and others in the balance of plant control market.

The MKVIE is more in line with the recent offerings from ABB and Emerson. Its controllers and other hardware are much smaller as compared to the original MKVI. It's controllers communicate to the I/O packs via ethernet making them very easy to "distribute" around a plant or turbine, allowing GE to compete in a larger market.

> How much improvement from a customer's point of view have they made? <
I can't comment since I have little experience with the MKIVE.

> Also anyone ever wonder why GE went from Mark VI to Mark VIe in just six years.. <

With today's evolution of PC's and processors I think parts for control systems don't remain available as long as in past years. I have seen documents from GE that certain controller cards have been updated because GE is unable to get certain PC components from the manufacturer to produce new cards. As stated earlier I think the move to ethernet communication allowing the I/O to be distributed was probably the largest driving factor.

> The problem is we have Mark VI on one of our new Gas Turbines (GE Frame 5) & I would like to learn from other peoples experiences. <

As with any purchase of a control system, car, computer, etc, the day you purchase it the clock starts ticking. If the intent is to keep the control system for years to come my advice would be to maintain it well, purchase all the spares you can afford, and become acquainted with companies that can repair cards or boards as needed. GE states they will support systems for ten years after they cease production so keep that in mind.

I hope this helps and I look forward to others replies as well.

 

This is true: http://www.gepower.com/prod_serv/pr...Mark_VI_Control_Systems_Life_Cycle_Notice.pdf

Basically, the Mark VIe is now cheaper than the Mark VI, and far more capable. The Mark VI will still be supported for years, but there isn't any point in selling new Mark VI units.

 

Well we have a siginifcant investment in Mark VI on our Frame 7 Combined Cycle. We would like to upgrade our four Frame 5s with Mark VI so we have common inventory and the techs already have the MarkVI training.

Maintaining common equipment, especially when it is proven reliable, may be a reason to hold on the the Mark VI. I think GE should offer you both families.