Hi,

we have a speedtronic MK I controlling a Frame5 turbogenerator. we are going to upgrade the control system to MK V. we have two choices: Simplex or TMR. we are thinking about using simplex one due to small numbers of signals and simplicity of system. we are still working to choose one of the options, if you have any experience on the same project please inform us.

Thanks in Advance

 

This is very interesting; because GE doesn't sell Mark V Speedtronic control systems any longer.

There is a rumour floating around that GE sold the Mark V technology to one of their Business Associates in Asia, and perhaps you are purchasing it from that source?

At any rate, many people have found that SIMPLEX control systems are more than adequate for their purposes, if they can tolerate shutdowns when main control system components fail. Fortunately, with newer technology the failure rates are pretty low, but if you're buying a Mark V you should know that new spares are not available from GE.

TMR control systems can be very complicated to understand and troubleshoot. And because you have basically three of most critical components, you will have more card failures than with a SIMPLEX system which will require a larger number of spares to support. I <b>didn't</b> say the card failure rate would increase, because even if the card failure rate remains the same if you have three times the number cards the number of failures at the same failure rate will be higher. The difference with a TMR control system is that for the most part it's not necessary to shut down the unit to replace a critical card, whereas with a SIMPLEX system it's usually necessary to shut the unit down to replace a card if it didn't trip when the card failed.

If you don't have Dry Low NOx combustion and don't plan to convert to DLN in the future, then SIMPLEX is fine for many applications.
If you're truly buying a Mark V, then you should be very confident that the supplier is capable of configuring the Mark V for your specific application.

 

I had similar thoughts to CSA, regarding availability of Mark V.
Regardless, a simplex Mark V (or Mark VI), if properly configured, should be more reliable than a Mark I (or Mark II) control. While it will be less reliable (I am talking about running reliability here) than a TMR control, it will also be far less expensive. Especially when you consider the cost of all the additional instrumentation required to implement a TMR control system.

The core control part of a simplex Mark V (or VI) has fewer cards than the Mark I. Plus you eliminate most of the electromechanical relays.
If they are using Mark I control, they certainly do not currently have DLN combustion. The only low NOx combustion GE did with Mark I/II controls was wet - water or steam injection, and I think even those required the ITS temperature control.

 

I am also very surprised that you are talking about purchasing a mark5 whatever simplex or TMR as they are not anymore manufactured long time ago from GE (I think it has been stopped in 1995 or something like this)But it is not true that you won't find any spares in the fields as there are still a lot of this equipment all around the world (I can even give you a name of a company who will provide you with spares if you wish they can also provide complete mark5, second hand of course) on the contrary of Mark1 2 and 4 which becomes really museum equipments.

Now, about the choice between Simplex or TMR, answer in fact is quite simple it would depend of the degree of RELIABILITY you requires for your TURBINE (and not for your computer) With a critical application obviously you will require TMR as in case of failure of ONE computer you turbine KEEPS RUINING and it is only at the second failure (second computer to fail which is not quite common I can tell you Mark5 are really quite reliable computers) the you will trip your turbine and therefore you load Of course I will temper this with the amount of money you which to invest in this project but if this is not a problem I DO HEAVILY RECOMMEND TMR for CRITICAL APPLICATIONS if you can afford to "loose" the Load for some time (the time to repair any computer failure) then Simplex is enough and you will also save a lot of money.

it is also not true the TMR is less reliable than Simplex, I would say on the computer point of view obviously you have more components which can fail(but another time I have been working on this field for quite some time and frankly Mark5 are quite reliable) but if you consider the system (computer plus turbine plus your load) it is much more reliable than Simplex.