In GE 6FA gas turbine what stands for 6 and FA ?

 

Good question.

Unfortunately the answer is not simple.

GENERALLY, the number part of a GE-design heavy duty gas turbine designation stands for the electrical motor frame size of the turbine and axial compressor (NOT the generator--just the torque-producing part of the machine). There are websites which can be used to look up electrical motor frame size dimensions (Frame 3, Frame 5, Frame 6, Frame 7, Frame 9)--they are LARGE machines, needless to say.

The next alpha character(s) refer to the version of the machine Frame size. So, a 6FA is the FA revision of the Frame 6 heavy duty gas turbine.

Essentially.

Except when GE designed the F-class revision machines back in the 1990s, they didn't want to invent a new Frame size designation--they wanted to continue to use the long-produced and trusted Frame size designation for Frame 6F- and Frame 7F and Frame 9F (and the A and subsequent successive sub-revisions (like FA, FB, etc.). Now the H and HA class machines--which are WAY bigger than any Frame 7 or Frame 9 electrical motors.

AND, to make things even MORE complicated, GE has started using .nn designations (where 'n' is a whole number) instead of alpha characters, so, for example Frame 9.03 instead of, for example, Frame 9FC (that's just an example; they seem to be switching things up even more....

As an operator or a technician working on GE heavy duty gas turbines it's just important to know a couple of things: IN GENERAL, as newer GE heavy duty gas turbines were designed, developed and released they almost always used tried and true, trusted and proven auxiliary systems (starting means; cooldown systems (turning gear; ratchet; barring means); L.O. system; hydraulic systems; trip oil systems; etc.). BUT, even that is changing now, too. So, people who were familiary with designs which have been used since the 1950s have to relearn new control philosophies and auxiliary systems and designations (device numbering systems). Not entirely impossible, but there is still a learning curve. Whereas for decades experience one had with a Frame 5 could be used to quickly understand a Frame 6 or a Frame 7 or even a Frame 9, even a Frame 3 (we're talking about heavy duty gas turbines designed by GE).

So, that's it. Suffice it to say that as the Frame size number increases, the power produced by the turbine and axial compressor increases, and now no longer can be compared to any electrical motor frame size. Any alpha character "suffix" refers to the revision (and sub-revision, if applicable) of the machine. The Frame size number is just a designation, and GE wanted to continue the same Frame size numbers (even though they no longer correspond to electric motor frame sizes) because it implied the new design was a scaled-up version of machines which had been produced for several decades (even though the F-class machines had a LOT of problems in their early product life--not because the design was marginal so much as because there was a HUGE shift in the way heavy duty gas turbines were used around the world. Instead of starting them and leaving them run for weeks or months gas turbines were started once or even twice per day--and the designs were not originally produced or planned for that kind of operation and the thermal stresses that puts on high-tech combustion parts and turbine blades--and especially axial compressor blades (stationary and rotating). But--GE made good on those machines, sometimes even using Antonov cargo planes to ship components quickly to sites around the world, at GE's expense. (One of the "benefits" of working with an American corporation that has been around for more than 100+ years and has a reputation to maintain and the cash to do it. Yes; some sites lost generation revenue, but they were all eventually made whole as far as the machine and its reliability. GE's reputation did suffer, and its competitors were quick to jump on the issues--as any competitor is likely to do to try to gain market share at the expense of the market leader. Many competitors' salespeople were heard to say, repeatedly and often at trade shows and conferences, "Ours is as good as GE!" when GE was at the top of its game.)