Hi,

We have an GE LM2500 equiped with one accelerometer + remote amplifier of charge then to the Speedtronic Mark V (HMI).

It says that the vibrations were measured only after 4500 TPM of TNH (GG speed).

but i cannot find where this limitation is:
where in files of MARK V included.

Or is the remote amplifier did this limitation.
thanks for your help.

When i use a shaker to simulate the GG vibration I can't read THE RESULT in HMI.

 

If you have an LM2500, then you most likely have what's known as a "Mk V LM" turbine control panel. While Mk V LM turbine control panels share a similar name and a similar operator interface (<I> or GE Mk V HMI), and similar enclosure and hardware to the Mk Vs used for heavy-duty gas- and steam turbine control and protection, the similarities just about end there. The list of differences is far longer than the list of similarities. (There were some "regular" Mk Vs used as LM2500 and LM5000 controls, but that was early in the spplication of Mk Vs to LM units. GE Aircraft Engine in Evendale, OH, USA, has some very specific requirements for control systems for all but the most basic LM engines--which the "regular" Mk V doesn't really come close to meeting.)

Where does "it" say that GG (Gas Generator) shaft speed must be above 4500 RPM to register vibration? The BBL pic (picture) file used in the CSP printout? The Control Spec? The Application Manual? The HMI Manual? The IDM (Installation & Design Manual)?

Seismic (velocity) vibration pick-ups do not NEED a rotational shaft speed signal (RPM) in order to indicate "vibration" (shaking, really...). Displacement- and accelerometer vibration measurements are most accurate when "filtered" by a shaft speed signal.

If "it" says that GG speed must be above 4500 RPM and you are simulating vibration with the accelerometer mounted on a shaker table WITHOUT also simulating speed . . . well, it probably needs to see GG speed or it's not going to work very well (as you seem to have found out).

So, you will need to find a ZERO-crossing (NOT zero-based TTL) frequency generator, disconnect the GG speed pick-up wiring from the Mk V, and connect the freq generator in parallel to the GG inputs and simulate a minimum of 4500 RPM _THEN_ start the shaker table.

The frequency generator output can be square-wave, sine wave, saw-tooth--as long as the output crosses the zero volt axis; you only need set the voltage output magnitude to approximately 3-5 VAC peak-to-peak, but generally no higher than 10 VAC pk-to-pk.

BEWARE: The Mk V will think the turbine that's connected to it IS RUNNING when you turn on the frequency generator. ALL MANNER of alarms will be annunciated; fans and pumps and motors will start--it can be quite intimidating. NO fuel will be admitted, but it's best to close the manual fuel shut-off(s) before simulating speed--just in case. And, it's usually a good idea to "rack out" (open the breaker/disconnect switch) to most fan/pump motor starters just to prevent a lot of pandemonium when many things want to start and run and cycle. (Many "events" in the control of GE turbines are a function of some percentage of speed, so as the frequency input is increased in addition to pumps and fans and blowers wanting to start and run, solenoids will be energized or de-energized, also.)

There are few people in the world who really know and understand Mk V LM panels, or, even the few "regular" Mk V panels which were applied to some simple SAC (single annular combustor) LM engines; they had some unique printed circuit cards to accomodate the I/O (accelerometers, for example) and protection schemes and -I/O, and some unique BBLs (such as the vibration one you seem to have).

And the BBLs used in the Mk V LM control PROMsets, well, ... they just weren't documented very well anywhere. About all you can find are the "notes" in the pic files used in the CSP printout.

GE Aircraft Engines, located in Evendale, OH, has several really informative documents--the best one is what's known as the IDM, or, Installation & Design Manual. This document describes EXACTLY how an LM unit is to be packaged and controlled and protected--doesn't talk about the control system, but it does define compartment cooling requirements, fuel flows, oil flows (to the engine--not the generator), vibration alarm- and danger (trip) setpoints, Tnn control (i.e., "Base Load" temperature control) setpoints--basically everything.

They also have some control scheme descriptions, akin to the Control Specifications used for heavy-duty gas turbines, which were written by someone who wasn't all that well-versed in the Mk V turbine control panel, but they did attempt to describe how the turbine was to be operated, controlled, and protected with a Mk V turbine control panel (about 80% of the signal names listed in the document match those actually used in the Mk V turbine control panel; the rest were similar, but different...).

For some reasons, not every owner received either or all of these documents.... They're both full of good and useful information, though it has to be sifted through. No really useful information about the Mk V LM (or even the "regular" Mk V), though--sorry.

If you don't have these documents, see if you can obtain them from your OES (original equipment supplier), or even from GE.

Hope this helps! This author isn't all that familiar with Mk V LM panels, and wishes he couldn't even spell "LM". But that's another story for another forum/blog...someday.

markvguy

 

It is believed "LM" stands for "Land/Marine" or "Land & Marine," a reference to the non-airplane wing usage of these engines.

markvguy

 

If the Mk V is a "regular" Mk V, there is some information on accelerometer inputs in the Mk V Application Manual, GEH-6195, Sect. 7-9.2. If the Mk V is one of the Mk V LM panels, there is some information in the Mark V LM Turbine Control Manual, GEH-6353, Sect. 5-5-4.13, and Sect. 7-6.2. But nowhere is the 4500 RPM value mentioned.... The presumption is that it's a limit of the PROMset software, that is, the firmware on the printed circuit card that scales and conditions the signal; or, that it's a limitation of the BBL, but these are just presumptions.

Is "it" a note on your HMI display?

Who was the packager of the unit (i.e., was it GE, Thomassen, Stewart & Stevenson, or.?.?.?)?

markvguy