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Safety Certified PPRO I/O Pack
Difference between a PPROH1A (ordinary pack) and PPROS1B (safety certified pack)
1 out of 1 members thought this post was helpful...

Now with MarkVIe we can have a PPRO pack which is safety certified (IEC 61508), and it can be used in the IEC 61511 certified safety loops. please can you tell me exactly what GE added to the hardware or the software (board processors) which make it able to be safety certified?,

In other words what is the difference between a PPROH1A (ordinary pack) and PPROS1B (safety certified pack)? if and only if there is a difference.

1 out of 1 members thought this post was helpful...

I'm not an expert, so I'll refrain from spreading possible misinformation. :) However I'd read GEI-100709 carefully if you're looking for something specific. It covers the functionality and safety features of the PPRO S1B. It doesn't have an item by item list of differences from the non-safety version, alas.

thank you very much for your reply, i've checked my database and i couldn't find GEI-100709. I would be very grateful if you shared it with me. email :

thanks in advance

GEI-100709 is installed with ControlST; there should be a start menu shortcut.

[NOTE: The use of $ for spelling $IS/$IL is my own convention, and is, in my own personal opinion, a more accurate description of the estimation and calculation functionality of the equipment you are paying extra for.]

I'm no expert on this topic ($IS or $IL), but I can tell you this much for sure: The PPROSnx is more expensive, probably MUCH more expensive, than the Hnx version.

If I recall correctly, and the $IS/$IL Mark VIe equipment was just coming out when I left GE, one of the requirements for $IS/$IL certification was that it have extensive testing to certify that it meets specific MTBF (Mean Time Between Failure) and other requirements. Another thing I think that distinguished $IS/$IL systems from non-$IS/$IL systems is that there be some kind of password protection permanently enabled for making changes (of any kind--temporary or permanent), as well as a rigid and somewhat standardized method of tracking all changes.

There's also the whole idea of cradle-to-grave product lifecycle management (manufacturing to end-of-life disposal).

In my own personal opinion, $IS/$IL was born out of protectionism--making some laws/technical regulations that barred some equipment (from other nations) from being sold or used in a particular part of the world because they didn't meet some "standard" (and the nice thing about standards, as we all know, is that there are so many of them to choose from!). Those companies that promoted the adoption of these standards had long since been developing the equipment to meet these standards and only had to promote the adoption of these standards in order to prevent the sale of "non-compliant" equipment in their part of the world until or if other manufacturers could meet those standards. And, by hanging the word "$afety" on the whole concept/scheme these manufacturers could claim their equipment was better, and that equipment not meeting the standard was inferior, and therefore, by extension, dangerous. (Yes. Dangerous.)

What most people don't realize that in determining and $IS level (or $IL) for a particular application (turbine overspeed, for example), there are assumptions that have to be made about certain desired aspects of the level. And that concept of "level" applies as well--does one want $IL-1 or $IL-2 or $SIL-3 or, the nearly unobtainable $IL-4--is a choice. (Isn't this fun?) It's just a choice to be made based on knowledge and experience, sometimes dictated by some local technical regulation or requirement, but is often just a decision--conscious or otherwise--which greatly affects all of the ensuing calculations and estimations.

As well, the data used to calculate a level is also often an estimation of past issues (turbine overspeed, for example--which is one of the main functions of PPRO I/O Packs), and sometimes only in a small geographic region of the world which doesn't reflect the level of training and sophistication (both higher and lower!) in other parts of the world. So, it's all just "statistics." And how does the quote go: "There are lies, there are damn lies, and there are statistics!" (That may be a little excessive, but it's not far from the truth. Statistics can be, and often are, manipulated to promote a certain point of view or belief. This is no different.)

But, again, the one thing you can be absolutely certain of is that the price of the Snx part will be significantly higher than its Hnx counterpart. Will it have better components (resistors; capacitors; op-amps; A/D and D/A converters; ICs (Integrated Circuits); etc.)? Yes, and this adds to the cost. Will it have some unique software for tracking and making changes? Yes. (And this also adds to the cost.)

As demigrog2 recommends, have a read of the listed GE publication, and then compare that to the generic Mark VIe System Guide's (GEH-6721, I believe) description of the capabilities of the PPRO and you will likely learn a little more about the specific differences. But, neither publication will tell you how much the difference in price is--and from what I remember, that is significant.

Here's an extremely high-level overview of $afety Instrumented Systems. While they may have started in the petroleum and refinery industries, their adoption in certain parts of the world was primarily driven by protectionist ideologies.

Here's two more:

The last time I saw a printed copy of IEC-61508 it was more than 800 pages--double-sided. That probably included most, if not all, of the various dash sub-documents, but, suffice it to say that it is voluminous. And that means that in order to implement it properly and in accordance with the recommendations it will take a lot of study and paid attendance at seminars and professional courses, as well as texts and reference books and membership in various societies and forums. Just more money!

I would be extremely interested to know, isulamu, if your part of the world (region; country) requires $afety Instrumented Systems for any particular turbine (high-speed rotating equipment) application(s) (such as overspeed protection), or if this is what GE is recommending. If they are recommending this, what is their rationale/justification for the recommendation?

GE and their lawyers have determined that as a major manufacturer of high-speed rotating equipment that are "required" to sell you the very latest and greatest technology and control and protection schemes for your existing turbine, auxiliaries and generators. (This requirement is more about protecting them in the event of some kind of catastrophic failure and ensuing litigation.) So, when you have a turbine that is running fine with an older control system and you purchase a new control system from GE you are told you are getting the very latest and greatest technology including all new and relevant GE standards for operating and protecting turbines. They WILL NOT, however, be able to tell you exactly WHAT they are providing--that will be up to you to "discover." And you will "discover" the new features the very first time you click on START if you're running gas fuel. Because the start-up time is going to be much longer than it was before because the testing scheme provided with the new control system--that no one told you about. And, that they will refuse to remove or change. And which can cause serious starting reliability issues on older equipment if that equipment is not in or maintained in a near new condition. And, that's just one example of the "new and improved" you will receive with your new control system. There will be many others, likely including the Emergency L.O. Pump test (which will also add time to the start-up sequence). And, if you ask for a list of what changed from the old control system, you will get absolutely nothing. Zero. Zip. Zilch. Nada. Niente. Squat, or more properly, diddly squat (sorry for the colloquialism, but it's appropriate.)

But, you have what you were sold--the very latest & greatest and new & improved control system and operating schemes. And, all you really probably wanted was new control system hardware and a computer-based operator interface (HMI) with some data archival and retrieval capability that runs your turbine with a higher degree of reliability and performance than was ever possible with the older control system. And, you thought the turbine operation was going to remain the same--just START and everything would be relatively identical but with new and improved technology. If it took 21 minutes to get from zero speed to synchronization before, you assumed it's still going to take about 21 minutes. A reasonable expectation, sure. But, probably not at all what's going to happen. GE has pre-established what they believe is the ideal start-up acceleration rate--which will likely be slower, but possibly faster, than the current control system was configured to provide. So, expect some changes to the way your turbine starts and runs and is operated--even though you thought all you were really getting was new modern hardware and a new modern operator interface.

Anyway, just trying to prepare you, or anyone getting a turbine control system upgrade from GE. I still believe the purpose-built hardware of the SpeedTronic/Mark* control systems is the best for any kind of turbine's operation and protection. But the way it's being sold and packaged, and installed and commissioned, leaves a LOT to be desired.

Thank you for taking the time to respond, and building on what you said i will ty to comment some of your statements.

>But, again, the one thing you can be absolutely certain of
>is that the price of the Snx part will be significantly
>higher than its Hnx counterpart. Will it have better
>components (resistors; capacitors; op-amps; A/D and D/A
>converters; ICs (Integrated Circuits); etc.)? Yes, and this
>adds to the cost. Will it have some unique software for
>tracking and making changes? Yes. (And this also adds to the

This was the reason number one for this thread, for better component or even different ones. yes i do agree, but the software? I have been checking the GEH 6721, 6722. and what confuses me is that the logic algorithm in both is the same (overspeed, overtemperature...etc). even the one of YPRO, most of paragraphs are the same. only change is the name of IO pack. The only statement i found different is "The PPROS1B is an IEC 61508 certified version for use in IEC 61511 certified safety loops."

Okay! i accept that. this is why in our Mark II upgrade (which i will talk about later on in this reply) we will be using the Sxn version for more $afety! now if i am not wrong! will i be able to replace this PPRO with YPRO (which means more $afety), and my turbine will be working normally? they are the same no? (i may be changing the TB too). this is what i want to gain more insights of! is the using of those packs.

>I would be extremely interested to know, isulamu, if your
>part of the world (region; country) requires $afety
>Instrumented Systems for any particular turbine (high-speed
>rotating equipment) application(s) (such as overspeed
>protection), or if this is what GE is recommending. If they
>are recommending this, what is their rationale/justification
>for the recommendation?

I am from Algeria (north africa), and we are having a system control upgrade from MK II to MKVIe. the work hasn't started yet, but i could take a look at the panel and its components. as far as i am concerned we do not have a SIS requirement from the authorities, and those choices have been made or proposed by GE. and even i have not been part of the engineering phase, i am quite sure their justification is "latest technology" and the availability of spare parts in the future.

>GE has pre-established what they
>believe is the ideal start-up acceleration rate--which will
>likely be slower, but possibly faster, than the current
>control system was configured to provide. So, expect some
>changes to the way your turbine starts and runs

I will keep you updated of any changes when we will start our turbine again with the new control system.

Thanks again


I want to ask if you're doing any studying of ToolboxST and how to use the various features to troubleshoot and understand how the turbine will operate or operates--so that you can document the changes from what was in the Mark II?

Understanding hardware is good; don't get me wrong. But, the thing you want to know about hardware is: Don't let the commissioning person leave before EVERY Diagnostic Alarm is resolved. You're going to hear, "It [the Mark VIe] does that all the time." That's not an acceptable excuse. The commissioning person, if unable to resolve the Diagnostic Alarms himself, can get support from the vaunted GE PAC (Power Answer Center) and is in the best position--during commissioning--to clear all Diagnostic Alarms before leavning. Don't let them get put on some punch-list (a list of unfinished tasks which the Customer and GE agree to complete "some time later"). Because, getting someone back to site is easier said than done.

My recommendation is to get the HMI(s) and the Mark VIe communicating, and then immediately start resolving ALL alarms--and I can promise that some Process Alarms will disappear from the list when all the Diagnostic Alarms are resolved. Are they hard to clear? Some of them are easier than others, but by clearing them BEFORE you begin loop-checking and commissioning and start-up activities will mean that any Diagnostic Alarms that do arise during commissioning and start-up activities will likely be real and true conditions which should be investigated.

Then, clear all Process Alarms possible. You may not have gas fuel supply pressure (if the unit runs on gas fuel), so that one may have to remain until gas gets admitted to the stop valve. But, by going through all of the Process Alarms you will find some wiring errors, some inversion masks that are incorrect, and you will complete some loop-checks at the same time.

Then start loop-checking all the inputs and outputs (I/O). The fastest and most efficient way to do this is by compartment/area. So, for example, make a list of all the devices (you may overlook one or three) in/on the Accessory Compartment, such as the Trip Oil Pressure switches, the CPD transmitter, the L.O. Reservoir Level switches, the L.O. Temperature switches, the ratchet Jog P/B (Push-Button), the Jaw Clutch engagement limit switch, etc. And loop-check all those devices. Then move to the Gas Fuel Compartment and do all the devices there (LVDTs, P2 Pressure transmitter(s), etc.). Then move to the Turbine Compartment, and the Load Compartment and the Generator Collector Compartment, then the Turbine Inlet Air Filter, etc.

You're going to forget a few devices, but you can go back and do them. If you loop-check based on the order of the I/O in ToolboxST, you're going be running back and forth between compartments/areas, and going to them multiple times. Doing the loops as above, you should only have to visit compartments/areas a couple of time--first to do all the I/O on your list, then when you think you're all done and you go through I/O in ToolboxST you will see you have missed a few and you will have to go back only once, maybe twice. But, if you have to go back to the Access. Compt. multiple times, and the Load Compartment multiple times, and the Inlet Filter house multiple times and the Turbine Compartment multiple times, you're going to be wasting a LOT of energy and time.

You will likely know more about where the various devices (pressure switches; limit switches; level switches; transmitters; solenoids; etc.) are located than the commissioning person sent to site, so be the one that goes out to the devices in the field and does the work of changing states or disconnecting wires or jumpering the contacts to loop-check the device. Sure, you won't be sitting in front of the HMI, but believe me, it gets boring watching for a "0" to change to a "1" or a "1" to change to a "0". And, you'll be helping the commissioning person a LOT.

And, again--be sure to learn how to use the Trend Recorder. That's going to be your most valuable asset as a technician and troubleshooter. It's not very difficult, but it does take some practice. And you can practice any time you want--because running the Trend Recorder DOES NOT affect turbine operation in any way. It can't trip the turbine, it can't shut it down, it can't make it change load. It can only record data, which can be saved to files on the HMI hard drive and re-opened later for detailed analysis. You can add/have LOTS of point in a Trend Recorder file, and when you are viewing the data (when the Trend Recorder is not running) you can temporarily hide the data points for the signals which are not appropriate. You can change the pen widths and styles and colors for any signal, which can make looking at the data easier. You can change scaling which can also help with analysis, and you can stack traces. The Help for the Trend Recorder is VERY good, and I believe there is at least one GEH publication for using the Trend Recorder, and a couple of GHTs (GE How-To's???).

That's another thing--have a look of the various files and directories on the HMI. There is a LOT of information on the hard drive--LOTS. Mostly in .pdf files with cryptic names, but you can create your own directory (folder--say on the Desktop) and copy files you want to keep handy and rename those files (which doesn't change the contents one bit!) so that you can easily remember what information is in the file. For example, you will find a couple of files with the name GEH-6721 (Vol. I and Vol. II, at a minimum). Those are the Mark VIe System Guides. Change the names (by right-clicking on the file name and selecting 'Rename') to 'Mark VIe System Guide Vol1.pdf' and 'Mark VIe System Guide Vol2.pdf' for easy reference! Do this as you go through the various .pdf files (you will have to open each one to see the title page, and write down the title) and you will be amazed at all the information that is available to you. Things you won't have time at the present moment to go through, but things you will want to revisit later.

Also, you want to work with the commissioning person to learn how to find the hourly- and Trip History log files, and how to open them with Trend Recorder. They are very similar to regular Trend Recorder log files, and they can be VERY helpful when troubleshooting abnormal operation or trips--because there is some limited short-term data which is ALWAYS being captured and stored in "rolling" files on the HMI--if you know where to find them and how to analyze them. So, learn the locations of those files and how to analyze them, and how to save them to another location (because they will eventually get over-written/deleted). Good information to know--be sure to learn about that!

Hope this helps. I think worrying about whether or not you need a PPROHnx or a PPROSnx or a YPRO or they can be substituted is not a very good use of your time at this point. Sure, you might have been asked to try to purchase a minimum set of spares for the new Mark VIe, but you have to work with what you've got--so, just do it. It sounds like the panel is already at site or is already configured, and changing that without a LOT more knowledge is going to be impossible (trust me). Just work with what you've got, and try to concentrate on learning the things that are going to be of most help going forward when you have to troubleshoot the system.


First of all i want to thank you for helping me with your advice during commissioning. i was aware of some of them (especially the fact that i should not let the commissioning engineer leaves without resolving all the Diagnostic alarms. you have mentioned it before in an other thread), but you gave me many other details.

In our station we have MKV and MKVI also, so i am familiar with all MarkVIe features that you mentioned. also i have a MarkVIe simulator which i am working on.

The reason of this thread is not only what should i choose for our project, or what is the perfect choice. As a preparation for this upgrade i have studied the markVIe, and bit by bit i have dealt with the markvieS. then i have started to have questions which i need to answer. if you noticed, i made a thread before this one talking about the difference about MKVIe and MKVIeS (

And recently as i am trying to gain more insights ,i was confused about the use of PPROSNX. Yes you might find this as an exaggerated meticulousness and you may be right.

thanks again


I see a LOT of people who get hung up on some minor detail and it prevents them from being able to learn anything else (yes; until they get their one question answered to their satisfaction (even if it's impossible to answer the question with a satisfactory answer because of perceptions and conceptions and beliefs) they are unable to focus on anything else, and end up losing a lot of valuable information and exposure.

Okay; so you have experience with Mark V and Mark VI and are now going to get a Mark VIe, probably with some Mark VIeS components, or some compatible components. I haven't been able to find the GEI that Demigrog2 mentioned yet, and as I said, I wasn't aware of a PPROSnx I/O Pack, only PPROHnx and YPRO I/O Packs. So, it would seem that GE has produced some new I/O Packs, for whatever reason (probably for being able to use the same hardware in multiple different applications which they are wont to do). That's good; because most people I encounter don't know the first thing about how to configure a Trend to do troubleshooting, or where to find the Trip History or Alarm History files. And it's very difficult to provide help without actionable data (trend data of some kind, along with Alarm Logs). So, if you're good with that, then that's great.

Let us know how your project goes--and best of luck!