i'd be grateful if someone can briefly explain what's the difference between TTXD_x and TTXD1_x in GE Speedtronic Mark V Turbine Control System?

Which 1 is more important to monitor ?

What's the mathematical formula relating the two ? Can in be calculated ie. TTXD1_x = some formula * TTXD_x ??

pls help me sir.

 

The easiest way to see what each of the arrays consists of is to use a Demand (User-defined) Display for each array and then analyze the results.

In general, TTXD_nn is the "raw" value of the exhaust T/C feedback from the numbered location. For example, TTXD_7 would be the raw exhaust T/C feedback from the exhaust T/C at location number 7.

TTXD1_nn is the "massaged" value of exhaust T/C feedback from the numbered location. (T/C output at elevated temperatures degrades over time and so there is a little "multiplier" in the algorithm that attempts to account for the degradation and that's why there may be a slight difference between TTXD_7 and TTXD1_7 if the multiplier is in use for your site.)

There's also TTXD2_nn.

Again, the best way to get an understanding of all these is to look at the algorithm in the CSP where they are used and generated, and then to put them on displays where you can analyze them and see how they "work".

I believe that the "massaged" value (TTXD1_nn) is the value that is used in the control and protection of the unit, and are generally the values displayed on the Exhaust T/C display. But, that can vary from site to site, so check your CSP and display configurations to be sure.

 

Hai to all,

TTXD_1 is the exhaust temperature measured by the thermocouple no-1

TTXD1_1 is the compensated exhaust temperature value. This is calculated value based on the Exhaust thermocouple measured value.

Normally TTXD1 is the thermocouple array by position.

TTXD2 is the exhaust thermocouple by value.

waiting for reply

 

TTXD1_x is the calculated compensated value of the measured raw value TTXD_x.

Due to construction/physical limitations the thermocouples are not located at the ideal location in the exhaust. The multiplication constant used is TTKXCOEF. There maybe separate ones for part and base load.

The value is dependent on the frame size. Some records at hand show for a Frame 6B TTKXCOEF = 0.9955, 9E = 0.989, and a 7E = 1.0. The GE performance guys often change this value to squeeze out a bit more power.

 

The originator asked what was the difference between TTXDn and TTXD1_n and which was the more important parameter to monitor. Physical placement of exhaust T/Cs is accounted for in the monitoring scheme.

GE performance engineers have the data, the software applications and the knowledge to properly adjust performance characteristics to optimize the power output of a gas turbine to match the exact on-site operating parameters, which may differ slightly from the expected parameters supplied when the turbine was being ordered and built. (For example, the exhaust duct back-pressure may be higher or lower than expected, or a change in inlet air filter media or the addition of a chiller or evaporative cooler may impact the inlet pressure drop, and these can be measured and accounted for only during on-site testing and analysis.)

Making adjustments to any exhaust temperature control-related parameter without express knowledge and understanding of all the knock-on effects is not advisable.

The value of any exhaust temperature control-related parameter is specific to a particular turbine and it's operating conditions. It's not uncommon for two Frame 9Es at the same site, installed at two different times, to have slightly different parameters and yet still produce virtually exactly the same power output. There are many, many variables which affect exhaust temperature control, some of which can be automatically compensated for and many which cannot.