During weekly Mix fuel operation of Gas turbine Frame 9E following Diagnostic alarms appeared on screen and they are not getting reset.<pre>
><R>0058 TRUE DALARM DCC I/O CARD OBJ ID #14 RESET
><s>1696 TRUE DALARM TCE1 TMR CHECK TROUBLE ,ETR1
><s>1697 TRUE DALARM TCE1 TMR CHECK TROUBLE ,ETR2
C>1824 TRUE DALARM VOTER MISMATCH, <r> 28FDA
C>1825 TRUE DALARM VOTER MISMATCH, <r> l28FDA
C>1826 TRUE DALARM VOTER MISMATCH, <r> l28FDA
C>1827 TRUE DALARM VOTER MISMATCH, <r> l28FDA
C>1832 TRUE DALARM VOTER MISMATCH, <r> L5E_TCEA
C>1833 TRUE DALARM VOTER MISMATCH, <r> L4_FB
C>1834 TRUE DALARM VOTER MISMATCH, <r> L52B_SEL
C>1835 TRUE DALARM VOTER MISMATCH, <r> l12H_P
C>1836 TRUE DALARM VOTER MISMATCH, <r> l12L_P
C>1838 TRUE DALARM VOTER MISMATCH, <r> l14L_ZE
C>1840 TRUE DALARM VOTER MISMATCH, <r> l30AS1
C>1841 TRUE DALARM VOTER MISMATCH, <r> l30AS2
C>1842 TRUE DALARM VOTER MISMATCH, <r> l30AS3
C>1846 TRUE DALARM VOTER MISMATCH, <r> l4ETR1
C>1847 TRUE DALARM VOTER MISMATCH, <r> l4ETR2
C>1848 TRUE DALARM VOTER MISMATCH, <r> l4PTR1_FB
C>1849 TRUE DALARM VOTER MISMATCH, <r> l4pTR2_FB
C>3534 TRUE DALARM VOTER MISMATCH, <r> TNH_OS</pre>
Kindly suggest which card like PTBA TCT, TCEA I SHOULD CHECK OR JL CABLE 1, 2, 3, 4, 5, 6 NEED TO BE CHECK

 

syed_hassan08,

Your post is unclear. Also, without time/date stamps of the alarms in the list below it's very difficult to say what initiated the problem.

<b>IF</b> the alarm at the bottom of the list is the first alarm in the string of alarms, then it would seem the TCEA in Loc. 1 of the <P> core (also referred to as <X>, and associated with <R>) has lost (at least temporarily) its turbine shaft speed input signal OR the its turbine shaft speed input signal has exceeded the <P> overspeed setpoint. This would cause the other Diagnostic Alarms in the list because <X> has determined the turbine should be tripped.

To view this, use the Prevote Data Display, and search for signal name TNH_OS. The value should be the same (when the turbine is running) for all three processors. (Remember, <X> is associated with <R>; <Y> (the TCEA in Loc. 3 of <P>) is associated with <S>; and <Z> (the TECA in Loc. 5 of <P>) is associated with <T>.)

If the Mark V was provided new with a new turbine, then there should be six (6) turbine shaft speed pick-ups. One each for <R>, <S> and <T>; and one each for <X>, <Y> and <Z> in the <P> core. The three for the <P> core will be connected to the PTBA in Loc. 6 of <P>, at terminals (1) & (2) (for <X>), and terminals (5) & (6) (for <Y>), and terminals (9) & (10) (for <Z>). You can also use a digital frequency counter, or a VOM with the ability to measure frequency, to monitor the inputs at the terminals (NO; connecting a frequency-measuring device to the terminals will NOT trip the turbine). GE makes it easy: 1 Hz equals 1 RPM, so 3000 Hz on the frequency measuring device would equal 3000 RPM.

It's odd, though, that only during the weekly test of mixed fuel operation this alarm would occur....

Depending on the vintage of Mark V and the PROMsets installed in the Mark V, it may be possible to initiate a MASTER RESET to clear the alarms--presuming the <P> overspeed condition is resolved (in other words, <X>'s value of TNH_OS is the same as <Y>'s and <Z>'s). If that doesn't work--and all three protective processors are indicating the same value for TNH_OS, you could power down <X>, wait approximately 30 seconds, and then re-apply the power to <X>. Presuming there are NO other Diagnostic Alarms, this will NOT trip the turbine if it is running when you cycle the power to <X>. (The protective processors (TCEA cards) in <P> are designed to be independent and are able to tolerate this--again, presuming there are no other Diagnostic Alarms, and that the condition that caused the alarms has been resolved.)

But, again, it's hard to imagine why one turbine shaft speed pick-up would not work correctly only during mixed fuel operation. And the bit about the alarm for persisting for 12 seconds is also very unclear and confusing.

Please write back to let us know what you find!

 

It seems speed pickup an issue but as CSA said why it appear only in mix fuel operation is strange.

Please try to replace the defective magnetic pickup and see.

Take care
G.Rajesh

 

Dear CSA

Alarm starts from the top of the list.

 

Dear syed_hassan08,

What have you done to troubleshoot the problem, and what were the results of your troubleshooting?

Have you looked at the Pre-Vote Data Display as suggested? If so, what did you observe? If not, why not?

Have you tried changing any cards or cables? If so, what were the results?

Again, it isn't really logical that these alarms would appear only once a week during a test of the liquid fuel system. So it's difficult to suggest what might be the problem and what to do to try to resolve the problem. You have not provided enough information--except to say check all the cables on the TCEA card in Loc. 1 of the <P> core. It's suggested to do this with the turbine at zero speed and with <R> and <X> powered down.

What changed prior to this problem starting? Was a maintenance outage performed? Was a card changed in one core, and if so, which card in which core?

Again, <b>from the information provided,</b> this is not a logical problem. So you're going to need to provide a LOT more information for any useful suggestions. So, tell us more, or start checking cables and changing cards one at a time (with the turbine at zero speed). And hoping the problem goes away as mysteriously as it seems to have appeared. Leaving you with a pile of questionable cards and no clue as to what the root cause was or how to prevent it from happening again.

Troubleshooting a problem like this is (or should be) a logical process but without more information we can't suggest a logical progression. It would be wonderful if everyone could provide little or no information about a problem to an Internet website and get an exact solution to the problem. But that's an unrealistic expectation.

Best of luck. Please write back with the requested information if you want more help. Or write back to let us know what you did to resolve the problem.