So,lets say I have a GE frame 5 machine, and I have 13 thermocouples.How many of them need to be faulty for the machine to have a trip?Also how does the exhaust thermocouples open trip L86TFB happen?

 

Of course I have 13 of them,4 of them connected to 2 simplex boards of the PCAA and another 5 of them connected to another simplex TERMINAL board of PCAA

 

nikidi.control,

Have you tried looking at the Item Help or Block Help for the block that generates the L86TFB logic signal? If so, what did you discover?

Without actually being able to see the block generating L86TFB in the Mark* at your site, we can’t say anything more with any degree of certainty. If the turbine uses Mark VI or Mark VIe you should be able to right-click on the block that generates L86TFB and be able to click on Item Help or Block Help and get some written description of the internal workings of the block if you can’t follow the signals through the pictorial representation in the block.

Prior to the L86TFB scheme three t/C values below a certain temperature when the unit was running would result in a trip. The philosophy is that a single failed T/C is a serious problem; two failed T/Cs is even a more serious problem. Three failed T/Cs is indicative of a failure to recognize and timely resolve what could be (and often is) a more serious combustion problem.

People always tell me the Mark* will protect the turbine, and when it does trip the turbine to protect it they always say, “The Mark* is so unreliable!!!” And when the Mark* doesn’t trip the turbine and the turbine gets damaged because the operators haven’t taken appropriate action to protect the turbine they always tell me, “The Mark* isn’t reliable!!!”

If the Mark* took action for every protective condition that operators—AND their supervisors—failed to recognize or take appropriate action for the Mark* would have an even worse reputation than it does!

There’s a saying that goes, “You can’t please all of the people all of the time.” And it’s very true. Especially when it comes to automation—which has been promoted to do so much. But still has a long way to go to really begin to reach its potential. (No matter what the salespeople say—and they say it a lot.)

 

nikidi.control,

Have you tried looking at the Item Help or Block Help for the block that generates the L86TFB logic signal? If so, what did you discover?

Without actually being able to see the block generating L86TFB in the Mark* at your site, we can’t say anything more with any degree of certainty. If the turbine uses Mark VI or Mark VIe you should be able to right-click on the block that generates L86TFB and be able to click on Item Help or Block Help and get some written description of the internal workings of the block if you can’t follow the signals through the pictorial representation in the block.

Prior to the L86TFB scheme three t/C values below a certain temperature when the unit was running would result in a trip. The philosophy is that a single failed T/C is a serious problem; two failed T/Cs is even a more serious problem. Three failed T/Cs is indicative of a failure to recognize and timely resolve what could be (and often is) a more serious combustion problem.

People always tell me the Mark* will protect the turbine, and when it does trip the turbine to protect it they always say, “The Mark* is so unreliable!!!” And when the Mark* doesn’t trip the turbine and the turbine gets damaged because the operators haven’t taken appropriate action to protect the turbine they always tell me, “The Mark* isn’t reliable!!!”

If the Mark* took action for every protective condition that operators—AND their supervisors—failed to recognize or take appropriate action for the Mark* would have an even worse reputation than it does!

There’s a saying that goes, “You can’t please all of the people all of the time.” And it’s very true. Especially when it comes to automation—which has been promoted to do so much. But still has a long way to go to really begin to reach its potential. (No matter what the salespeople say—and they say it a lot.)

Thanks for your reply CSA!Actually I saw that block and I gave it more thought and actually,although normally a gas turbine would go in trip if it had 4 or more faulty thermocouples this would in trip if it had less than 3 functioning thermocouples!The reason why this was happening was because the logical variable which enabled this function(if 4 or more TCs are not working well) was disabled