In our installation we have gas turbine MS5002 controlled by MK5 system.

I want to know, the formula used to calculate the COMBUSTION MONITOR ACTUAL SPREAD Signal Name TTXSP1 shown on the TTXSPV5 –Combustion Spread Monitor BBL.

Thanks for any input

 

You know, people who are familiar with Woodward's GAP program just swear that it's better than GE Speedtronic logic diagrams. They are adamant, but that do you see when you look at the logic? Empty blocks. You have to know what the block does or read some manual (which is sometimes not correct for the version of GAP being used) or look at some help file which also does not match the version of GAP being used.

On the Mark V, you can actually see what's happening inside the block. If you follow the inputs, you can see exactly what's happening. It's not easy, but it's all there. Every bit of it. And people complain because the internals of the block aren't "live", but the entire formula is there. All of if.

Create a User Defined Display and put the two arrays created in the block, JXD1_n and JXD2_n (I think those are the right CDB pointnames; look in your block to see them). The algorithm basically sorts the exhaust T/C inputs into two arrays: one for the values sorted from highest to lowest, and one for the exhaust T/C number associated with the highest to lowest values. That way the algorithm can check for adjacency to see if the highest and the lowest and the highest and the second lowest and the highest and third lowest are adjacent (close to each other). It calculates each of these values as TTXSP1, TTXSP2, and TTXSP3. And, then it generates logics based on the various combinations (L60SP1, -2, -3, -4, -5, and -6) and uses them in some rungs to determine if there is a real problem which needs to trip the turbine.

***NOTE*** I don't have a CSP with a TTXSPV5 block, and there are some subtle differences between different blocks, so CHECK YOUR BLOCK TO BE EXACTLY SURE HOW IT WORKS

Because a turbine can have a 240 deg C or even a 400 deg C spread, but if the highest and lowest T/C values are opposite each other, that doesn't mean the turbine should be tripped. If the highest and lowest T/C values are

 

Here is a picture, I hope it will help.

Exhaust temperature spread:
This function shows the asymmetric spread of the exhaust temperatures among those thermal couples. It can show them animatedly by clicking the "Auto Refresh" menu item.

http://www.leiosoft.com/ana/win/eng/Snap4.png