if suddenly gas fuel valve gets its complete open, in your thought, what will be the first protection work? over speed or exhaust temp.?

 

If I am not wrong, machine must trip on 'GCV not following reference'

 

GE-design heavy duty Frame 5 gas turbines are used to drive generators as well as compressors and pumps. Mostly, single-shaft Frame 5s are used to drive generators, and mostly two-shaft Frame 5s are used to drive compressors and pumps.

Is the Frame 5 single-shaft or two-shaft unit? (In other words, is it an MS-5001 or an MS-5002?)

Is it a generator drive or a compressor drive? If the unit is a generator-drive application, is it operated in parallel with other machines or in Isochronous ("island") mode?

The answer will depend on the application and type of Frame 5.

 

very simple. its overspeed..

dear Karim, plz tell me the actual sense of this question...so can tel u in detail.

Thanks,,
Ali Shah

 

Ali Shah,

If the unit is a generator drive being operated in parallel with other turbines and generators on a grid, and the fuel valve goes from some mid-stroke position to full open relatively quickly, the speed will NOT change appreciably and the unit will likely trip on exhaust overtemperature.

If the unit is a generator drive and the generator breaker is open and the fuel valve goes from some mid-stroke position to full open relatively quickly the unit will most likely trip on overspeed, but if the fuel valve moves very quickly it may trip on exhaust overtemperature.

If the unit is a compressor- or pump drive, and the fuel valve goes from some mid-stroke position to full open relatively quickly it will still probably trip on exhaust overtemperature, but depending on the load on the compressor or pump it may trip on overspeed.

So the answer depends on what the application is (generator or mechanical drive), and how the unit is being operated.

I was hoping to get the originator to provide more information and address the condition he would be experiencing, instead of trying to describe possible conditions for many different applications.

To GTG's answer, we don't know what type of turbine control system is being used on the Frame 5 in this question. Early Speedtronic control systems did not check for an error between reference and actual position to initiate a trip on an excessive difference. And, we don't know what condition resulted in the fuel valve moving to full open--perhaps the turbine control system had some input or inputs that drove the reference, and the actual position, to full open. In that case, there would have been no differential.

So, the answer to this question is not as simple as it might seem. We did not (as usual) receive enough information in the original post. I was hoping to engage the originator to get more information.

 

If there is any load on the turbine I think it will trip on high exhaust temperature before it gets to overspeed, regardless of whether the load is a generator or a compressor or pump. I am slightly less certain if it is a generator drive at FSNL (breaker open) at the time of the GCV going full open. The bigger question is whether the fuel is tripped off before the buckets melt.

The only machine I have inspected after a full fuel failure, a Frame 1002 compressor drive, never got to overspeed - the HP buckets disappeared first! (In addition to the failure that opened the GCV, corrosion prevented the hydraulic trip relay from operating, in a dramatic demonstration of Murphy's Law.)

 

To CSA,
As the question was asked in a very simple and to the point way. and you are very right that answer is totally depends on further clarification of the question, that is why I have asked karim sb to mention the sense of Question.
so lets wait.