GE Control System Toolbox for MarkVI Speedtronic Gas Turbine

To anyone reading this or any GE manuals for turbine control systems they are basically very generic descriptions of turbine control system operations. If you're looking to understand how a turbine is controlled and protected, the GEHs ARE NOT the way to do that. If you're looking to modify the application code or change settings/parameters or add or change inputs, you can probably find what you're looking for--but be aware (VERY aware!) that you will probably not find a step-by-step procedure for any of that. (The Mark* V manuals weren't bad for that; there were some funky flow-charts that were actually pretty accurate and useful; but that wasn't continued in the later Mark* turbine control manuals.)

A lot of people never had the "pleasure" of working with "DOS"--command-line operating systems. The early DOS manuals were very similar to what GE produces. If you wanted to move a file from one location to another on a IBM-compatible personal computer you had to create the new location (if it didn't already exist) using MKDIR, COPY the file to the new location, and then DELETE the file from the old location. So, it took at least three commands (until the MOVE command was introduced, that is--and even then one had to create the location to move the file to if it didn't exist). This was NEVER explained anywhere--except in the "DOS for Dummies" books, which sold millions of copies. Unfortunately, there's no "Control System Toolbox for Dummies" books.

Lastly, if you are trying to create new application code, even if you aren't adding any new I/O, AND you want to add any signal names created to a CIMPLICITY display--know that there about half a dozen different versions of the "proper" method for doing that, and NONE of them are documented in any manual, anywhere. AND, if the site is a multi-unit site there are even more steps for getting the new signal names into the CIMPLICITY project and on to other HMIs. It really is a kludge of a system, especially when it comes to the graphical user interface (particularly adding any signals, existing or new, to CIMPLICITY displays).

And NONE of it is for the faint of heart. The FIRST thing one has to do is MAKE BACK-UPS of the entire hard drive and its contents (if you haven't already and don't do so regularly). Mucking around with trying to figure out how to do this can create so many knock-on problems that unless you write every step you did down on a piece of paper, including filenames and locations, it's almost impossible to recover from some self-inflicted problems.

Getting the manuals isn't difficult; this particular one, if I recall correctly, is GEH-6403. There will often be a single alpha character at the end of the filename (like, GEH-6403A, or GEH-6403J), and some files have more than one volume. You can use your web-browser and search engine to find them on the World Wide Web. OR, if you have access to a GE Mark* HMI, you can usually find the files in one or two folders on the hard drive. GE seems to vacillate between making them easily available for downloading, to removing them from public access, to putting them back on line for downloading (but in a different location!), and repeating the steps over, and over, and over again.

The 'Help' in Control System Toolbox is mostly copies of pages from GEH-6403, so if you have access to Toolbox you can use the Help to dig a little deeper into the system.

But, if you're looking for some kind of overview of basic functionality, I recommend GEH-6421 as a starting point. AND, again, if you're looking for how a turbine is controlled and protected using Toolbox (or ToolboxST), there's NOT a manual for that. The best description of how any GE-design heavy duty gas turbine is controlled and operated is the application code that is running in the Mark*. It's like reading a foreign language, but it's not impossible to learn and understand. But it takes times and patience.

If you're looking for SOME basic control and protection information for a particular turbine, find and review the Control Specification provided with the Mark*. There are some parts of that document that are crap--especially the descriptions of how to "calibrate" LVDT feedback and to perform servo-valve polarity tests after changing a servo-valve. But, there's still a lot of good information in there.

Tchau!
 
Where to start to become a power plant control engineer.... presuming you will be working on GE-design Frame heavy duty and/or aero-derivative gas turbines.

To be a good control engineer one needs to be able to:

1) read P&IDs
2) know the location of control devices (switches, transmitters, sensors, local controllers, etc.) in the plant
3) know how various control devices work (RTDs, T/Cs, transmitters (2-wire, 3-wire, 4-wire), LVDTs, servos, flame detectors, switches (pressure, temperature, level, vibration, proximity), vibration sensors (velocity, accelerometer, proximity), speed pick-ups (passive, active)

Number 1 includes knowing what the positions of ALL manual valves shown on the P&IDs should be for normal running conditions, and during operations like off-line water washing. This is SO IMPORTANT, and yet most people don't know how to read the P&IDs to know what positions the manual valves should be in. The valves can be disturbed during maintenance outages by miscreants and be moved by technicians verifying device calibration/operation and forgotten to be put back in the as-found position. AND, when re-starting the turbine after a maintenance outage it's important that the majority of manual valve positions be checked and put into the proper position BEFORE clicking on START. As has been said before on Control.com: The three MOST IMPORTANT things prior to starting/re-starting a GE-deisgn Frame heavy duty gas turbine are: Valve line-up; Valve line-up; and, Valve line-up. Failing to verify manual valve positions ("valve line-up") prior to first fire or before re-starting after any maintenance outage will often result in tripping and/or alarms. Learn to do this. Have it incorporated into pre-start checks after any maintenance outage. It's hard the first couple of times, but it gets easier; it does. It takes an hour or so once one has done it several times, and it's really very important.

Number 2 above is one of the most overlooked and underrated aspects of being a good control engineer. One needs to be able to locate--quickly--all the devices shown on the P&IDs. The best way to familiarize oneself with their locations is to set aside some time during maintenance outages and go out and do your level best to find every device possible. It takes time, I'm not going to lie. And it means getting dirty, I'm not going to lie. It means using the Piping Arrangement drawing and the Electrical arrangement drawings in the Maintenance Manual provided with the turbines to locate some of the devices. Some of the devices are located in the Lube Oil tank (reservoir); some can be seen, some can't--but one still needs to know where they are.

Number 3 is really, really important. There are LOTS of controls technicians and even (so-called) control engineers that don't know how to properly connect T/Cs (thermocouples) in intermediate junction boxes. Yes; it's only two wires--but the way they MUST BE connected is very important. Not connecting exhaust T/Cs properly in the local junction boxes can result in some pretty serious performance degradation--just by misconnecting T/C wires! RTDs seem simple--just three wires. But, they, too, must be connected in a specific manner that most people never learned and don't understand. This is made even more important because of the way GE wires RTDs to the Mark*--electrically it is sound, but unless one understands HOW it's electrically correct it's VERY easy to introduce problems when just changing one RTD.

And, really, to be a good control engineer one needs to be a good operator--one who knows what's supposed to happen when and what's not supposed to be happening, too. Being a good operator means knowing the entire plant/turbine start-up AND shutdown process, NOT just sitting at a desk while the plant hums merrily along (just about any idjit can do that--and there are a lot of them in power plant control rooms these days, who don't have a clue what a proper start-up or shutdown is and can ONLY "operate" the plant once it's on-line and producing power, and even then they struggle responding to alarms (most don't--unless the unit trips, and then they ask, "Why did it trip?"). Operating a turbine/power plant is WAY MORE than just occasionally scrolling through HMI displays not knowing what's a good value for a parameter or what to be looking for, just scrolling to be doing something.

It's been said MANY times before on Control.com: One of the most over-looked aspects of operating a power plant (and this is important to control engineers) is Alarm Management. When an alarm is annunciated the operator needs to acknowledge the alarm (primarily to silence the audible or visible alert), read the alarm text message, work to resolve the alarm, and reset (clear) the resolved alarm from the Alarm Display. If an alarm is dithering (coming and going intermittently or incessantly) then there's something wrong with the sensor(s) the control system is using to detect the alarm or the wiring or the setpoint, OR there's really some condition that is bordering on the alarm setpoint and needs to be resolved. (Most "operators" don't know how to silence ("shelve") dithering alarms which have been determined to be nuisance alarms (this should involve the plant control engineer, the control technician, and an Operations Supervisor or plant manager) to prevent filling up the Alarm/Trip History queue which can make troubleshooting difficult if not impossible. A working Alarm Printer, with good printer ribbons and a supply of paper is one of the BEST Alarm Management and troubleshooting tools a plant can have. (Most "operators" think that dot matrix printers are "old" technology, and while they have been around for decades they are still the best option for printing alarms one at a time in a chronological order which can be very useful for troubleshooting. If the dot matrix printer quickly exhausts printer ribbons and the fan-fold paper is continually getting skewed and jammed--because of LOTS of dithering alarms, usually!--the problem IS NOT the alarm printer, it's the people (control technicians, plant control engineer, Operations Manager(s) and plant management that don't work to understand why the alarms are dithering and resolve the problem to prevent wearing out printer ribbons so quickly and causing paper jams....)

The Operations & Maintenance Manuals provided with GE turbines DO have some good information in them, but one has to be familiar with them and how they are put together. This means one has to sit down with the manuals, over the course of days and weeks, and scroll through the manuals ONE PAGE AT A TIME. You will encounter things which will surprise you that nobody in the plant knew about but it's been in the manuals all the time. Don't get hung up on reading every page, just scroll through the pages. I would use sticky note "flags" on the pages with information I want to go back to and read again or in more detail. But, it has to start with going through the manuals to understand where information is and where to look for similar information in the future. (Yes, electronic copies of the manuals can be easily searched but the search results aren't always what one is looking for; better to be personally familiar with the manuals and the information in the manuals even if using the electronic copies so that when there's an immediate need one can go to the manuals and quickly find the information one is looking for.)

There are some documents provided with GE-design Frame heavy duty gas turbines which every power plant control engineer needs to have copies of at his/her desk:

P&IDs (large format to be able to make notes on)
Control Specification
Device Summary
Single-Line Diagram
Generator Protection- or Control Panel elementary (schematic)
Generator Accessory Compartment elementary
Motor Control Center elementaries

These drawings are all SPECIFIC to a gas turbine (if more than one GT was installed and commissioned at the same time, it may be possible to have one set for all the machines).

A good power plant control engineer working on GE turbines will know every condition listed on the HMI Trip Display--what causes the trip, what the setpoint(s) is(are), what the alarm that warns of an impending trip--EVERY alarm on the display. Some of the trip messages may have more than one trip condition associated with it--so, again, it's VERY IMPORTANT to understand ALL conditions of EVERY trip alarm. (That's important to know, too: In the GE control philosophy EVERY condition that trips a machine has an alarm message associated with it that the operator should be able to use to understand why the unit tripped.)

Forget learning how to create/modify HMI graphics; GE doesn't properly document how to get signals on HMI displays and NOT every signal in the Mark* is available to put on the graphic displays, so adding them to the group that can be displayed can be very difficult and can cause real problems if one doesn't know all the steps OR make back-ups before attempting to add signals to the group that can be displayed on the HMI.
 
Finally, if you're looking for some document that describes what happens during a START or a normal, fired shutdown--while you may find one it's impossible to know for sure if it is SPECIFIC to the machine(s) you are working on. THE ONLY DESCRIPTION OF WHAT'S SUPPOSED TO HAPPEN WHEN FOR ANY MACHINE IS THE APPLICATION CODE RUNNING IN THE MARK*. FULL STOP. PERIOD. The function block diagrams used these days for Mark* application code are really just modified relay ladder diagrams (for the most part). So, if you don't know how to read relay ladder diagrams--learn how to. Some people (mostly idjits) will say, "Relay ladder diagrams are OLD technology!" And, while that may be true, it's simple and easy to understand and still works as a way of displaying control and protection schemes. GE Belfort likes to promote that they provide some good documentation for starting and operation and shutdown, and while it's better than that provided by GE USA, it's still lacking in many respects. The application code (programming and configuration) in ToolboxST is THE ONLY document that is 100% correct for any specific machine.

That's about it! Don't expect to learn everything at once (obviously). Once you are working on a site, get YOUR OWN copies of all the documents. Make notes as you learn. Read the NOTES section of every P&ID for subtly important details and information. Take every opportunity to go out to the machine and locate every control device you possible can; be prepared to get dirty doing so. You can't tell someone else where to find the device (if they don't know where it is) if you don't know where it is. Learn every condition that results in a turbine trip, and what the setpoints are for the trip conditions. Study the Operation & Maintenance Manuals, first by scrolling through them, possibly making some notes, and placing sticky note flags on things you want to go back to. Learn and understand Alarm Management, and do you best to teach operators (and their supervisors) how to manage alarms. Alarms--even Diagnostic Alarms (cryptic as they are--and they can be very cryptic!!!)--are important and not nuisances and need to be understood, resolved and cleared (removed) from the Alarm Display. Deal with dithering alarms--they ARE NOT NORMAL. Never have been; never will be. Having a bunch of dithering alarms leads to operators ignoring ALL alarms, thinking, "Oh; it's just one of those nuisance alarms again; they're such a bother." As the plant controls engineer you need to make sure any alarm that is detected and annunciated is real--or if it's not, then get it fixed. Yes; there's hundreds of alarms. Do your best. If you have questions, you can ask them here; with proper information we can give very good and concise answers.

Go forth and prosper!
 
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