Gentleman,

Some time behind happened a rain with some atmospheric discharge (rays) that affected some equipments and boards of some processors. One of these boards was TCCA of the processor "C." In this plate we have some entrances of analogical signs that are the example described below:

TTRXTM_CMD C -CTBA-037 Exhaust temp match reference [??]
AFPCS C -CTBA-046 Inlet air total press transmitter [96CS-1]
PQL1 C -CTBA-049 After Conical strainer pressure []
PQL2 C -CTBA-052 Fuel filter suction pressure []
PQL3 C -CTBA-055 Before conical strainer pressure []
SPAJUV C -CTBA-058 96AM-TL1-CH1, 200-450 PSIG []
STAJUV C -CTBA-061 96AM-TL1-CH2, 400-850 deg F []
SDAJ2UV C -CTBA-064 96AM-TL1-CH3, 0-150 inH2O
L90PSEL_REM C -CTBA-070 MWATT SET POINT REMOTE []

I begin her we visualized the problem in the entrance L90PSEL_REM that receives a sign of DCS to control the load of the Unit Generated remotely. When we selected a certain potency for the Turbine, independent of which was this potency, the same was in "-21MW" always. Then we decided to check all of the physical connections and electric signs to try to find some flaw type, however we didn't find none fails related. In this case we substituted the board TCCA. When substituting the board we had an alteration in the potency and now it arrived in the plate with "43MW", however still independent of the load that I selected in DCS this load continued static in "43MW."

It was then that we used "Diagnostic Counters Display" to verify the amperage of entrance of the signs and we noticed that all the analogical entrances were locked (statics) and independent of the variation that happened in the field instrument, nothing happened in Mark V.

The amperage measurement was accomplished in the threads of entrance of the card and it was verified that there was amperage variation. However, when they were put in the card, the same ones didn't oscillate.

Observation: we already changed the CTBA board.

 

This was covered in a recent thread. I wasn't quite clear on what was done to solve the problem, but it has also been covered in other threads.

You say you replaced the CTBA (the input terminal board). I'm not quite clear what an 'alteration in the potency' means.

What Diagnostic Alarms are present on the Mark V (on the Diag. Alarm Display on the operator interface and on the LCC/SLCC Display of the <C> processor)?

But, use the 'Search' function of control.com. You should be able to find some good help there.

 

Mister CSA,

I sought in it lists them and I found the solution for this problem in the post "Diagnostic alarm" being the answer given by the user "markvguy", as in described below:

"(4) Fuse FU1 is blown on the TCPS card in the Q core that the TCDA is attached to. Fuse FU1 protects the P24 voltage output, which is used to drive one of the relays (KR, KS, or KT) on the DTBA contact input terminal board. When dropped out, these relays remove the 125 volt reference signal from the TCDA which is used in generating the BATREF signal. If fuse FU1 is blown, the TCDA will generate all three of the following diagnostics, even if all cables are connected properly:

TCDA Plug JO1 is disconnected
TCDA Plug JO2 is disconnected
TCDA BATREF signal failure (plug JQ)"

Thank you very much for the attention and for the help.

 

I work for a living, too. Please, call me CSA.

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