Speedtronic control system and vibration measurements on Mark IV


Thread Starter

Jose Orlando R.

We are trying to upgrade our control system for 4 Frame 5 Turbines. We are actually more interested in updating the control system specifically for vibration measurements.

Right now we only get relative vibration measurements using velocity transducers on the housing of several points in the turbines. So I want some tips on what to do.

Probably a list of disadvantages of using a Mark IV control system would help.

Thanks guys!
The velocity vibration pick-ups (also called "seismic" pick-ups) on most GE-design heavy duty gas turbines have proved extremely reliable over decades. One of the reasons is that heavy duty gas turbine (and axial compressor) rotors are very large (have a lot of mass) and so when they start moving (vibrating) the effect can be determined with simpler velocity (seismic) pick-ups.

Have you experienced problems/failures caused by high vibrations you believe were not detected by the Mark V and the seismic vibration pick-ups? If so, please describe them.

I have been to MANY sites equipped with Mark IV turbine control systems over the years where the site personnel have replaced the original equipment sensors with sensors of a different make--which is not such a problem in itself; but the real problem is that all sensors do not have the same sensitivity. If a sensor with a different sensitivity (millivolts per inch-per-second) is used and the Mark IV isn't re-configured (and older Mark IVs couldn't be easily re-configured) then problems can result.

Improper maintenance; poor maintenance; and simply ignoring failed sensors have also led to problems. There are some "unusual" vibration monitoring configuration settings in Speedtronic turbine control panels, too, which quite often were not properly set during commissioning.

If you are simply looking for better vibration monitoring and an ability to detect what might be causing the high vibration and where to make a balance shot (and how much weight to add/subtract) you can always buy and install a stand-alone vibration monitoring system and use the high-high vibration output trip the gas turbine(s).

There are many manufacturers of vibration monitoring equipment in the world. Of course, there's Bently-Nevada (owned by none other than GE), Metrix, and many others. Have some representatives visit your site and make some recommendations. If you want to install a proximity-based vibration monitoring system (such as the B-N system), there is going to be a significant investment in installing the equipment in the bearings/bearing housings. (And, of course, if you buy anything from GE, you pay a premium to begin with. Though you don't have to have them install the proximity probes.)

The Mark IV, when properly maintained, is a fine turbine control system. Yes; it's aging, but there are still many of them in service around the world (though lots of them are being upgraded to GE Speedtronic Mark VIe systems by GE using their 'Mark IV Migration' packaged which saves a lot of wiring work.

There are also lots of control system integrators who sell PLC-based turbine control systems which have been used for decades on GE-design heavy duty gas turbines--mostly with the original seismic vibration pick-ups. Personally, I'm not a fan of such systems, as they usually require lots of signal converters and can be complicated, but if properly implemented they have proven to be reliable (though they almost never meet their oft-quoted selling-point of being able to buy parts "off-the-shelf" from a variety of sources; there are invariably some proprietary cards/components). If you go this route (PLC-based) be sure you are working with a vendor who has experience (LOTS of it) on GE-design heavy duty gas turbines.

Hope this helps!

Jose Orlando R.

We are actually having trouble with the history log. Apparently it only saves 10 registers of data per parameter, with times separated at an exponencial difference. This cant let me make a vibration analysis. Plus, the Mark IV doesnt have a database for this parameters. U would need to print the history log every certain time and then pass it to a computer.

Here is a list of all the equipment i've researched on, some are complete monitoring system and others strictly vibration.

- Bently Nevada 3500 series system
- Bently Nevada 3500 Encore system
- METRIX Setpoint MX2020
- Vibro-Meter VM600
- ABB CM11 System
- CEMB TDSP System
- Erbessd Instruments EIMU Continuous monitoring system
Jose Orlando R.,

The "trip history" function of the Mark IV is not configurable; it is what it is.

CSE Engineering, Inc., sells a PC-based HMI for the Mark IV that can be used to gather and archive data for Mark IV inputs and outputs and internal database signals. It would be much less expensive than replacing the entire Mark IV. (The URL is: http://www.itc-info.us.)

In fairness, there are other control system integrators also selling Mark IV-compatible operator interfaces; use your preferred Internet search engine. But be sure to get a list of references from any potential HMI supplier and contact them for their impressions and history with product service, support and performance before making any purchase.

The Mark IV is a good control system, and there are lots of spare parts available out there (though they seem to be increasing in price as the product ages). Are there better control systems out there? Yes, but there are really very few that bear consideration for GE-design heavy duty gas turbine control. And, if you ever wish to upgrade to DLN combustors, your choices will be limited--so if this is even a remote possibility be sure to consider it in your deliberations when choosing a turbine control system vendor.

Let us know how you proceed! Many people have similar concerns and needs, and through forums like this when people share their thought processes, concerns, and impressions a LOT of people can benefit.

Jose Orlando R.


Thanks a lot for the link ;). Im cheking it out right now and will make a decision y a couple of days. I'll tell u how it goes. Thanks for all the help.