MKV Simplex Problems

D

Thread Starter

Danno

We have a Simplex MKV and after the unit was put online and water injection was selected, the unit dumped. The <C> core did an automatic reboot and we smelled something burning. After some searching around I found that a relay had burned up on the TCRA card <CD>. The TCDA <CD> also did not have any LED's illuminated. I replaced both cards and although both <R> and <C> go to A7 status, there are still alarms present that deal with the Digital IO.

There are also some alarms on TCCA and TCCB relating to 4-20mA inputs out of limits and these are all on the <C> core.

Here are a few of the alarms I noted, but there are more that are most likely due to the IO not being recognized I'm assuming:

DTBA <CD> Battery system ground fault
DTBA <CD> Batery system LOW DC Volts
DTBA <CD> Battery system AC power charger failure
DTBB <CD> Generator Excessive volts/hertz (24G)


A few others that are curious:

TCD1 <C> Plug J01 Disconnected
TCD1 <C> Plug J02 Disconnected

These are two ribbon cables on the TCDA card that connect to the two TCRA cards in <CD>. Yes, they are connected correctly.

TCD1 <C> Battery Reference Signal Failure (Plug JQ).

All cables are connected correctly.

Is there a common theme here that I'm missing? I'd appreciate any insight to this problem.

Thank you!
 
I know you said the two cables connecting the TCDA to the TCRAs are plugged in, but are they plugged in correctly (ribbon cable trace to PIN1)? Could they be reversed (J01 in place of J02, and vice versa)?

I believe the TCCA is where the IONET for <C> "begins" and it "ends" on the TCDA in <CD>.

Sure seems like something is amiss with the cabling.

I don't understand the alarms signals as you have listed them, DTBA..., DTBA..., DTBA...., DTBB. I've never seen alarms like those; are you just indicating these contact inputs are terminated on these contact input terminal boards?
 
Could you provide some power supply data from your diagnostic counters screens? I believe you have some VERY serious grounds on CD core.
 
Yes, I just listed the termination boards for reference.

The cables are in their designated spots, double and triple checked.

We've since found that a solenoid on one of the water injection block valves was toast, and a level switch in one of the generator run-down tanks was causing a ground fault. These issues have been repaired.

We still have a negative ground fault and the voltage is at a 120VDC/-15VDC imbalance right now. If I remove power from the <C> we "gain" another 20V and I traced it down to the ribbon cable from the TCDA <CD> that leads to the DTBA <CD> termination card. If I disconnect the ribbon cable the fault imbalance is reduced by that 20VDC previously mentioned. Disconnecting the power to the DTBA card does nothing to the fault. We've disconnected every input on the card with no results. Just the ribbon cable plugged/unplugged makes the difference.

We also removed power one by one in the PD core and did not see any reduction of our fault other than when the power to the <C> core is removed (ribbon cable on DTBA ordeal).

So we still have those input alarms from the DTBA card as well as the 4-20mA inputs out of limits alarms.
 
I agree. Voltage readings from DIAGC menu:

P24 = 0.00
N24 = -29.97
P125 = 102.3
N125 = -27.2

Where does the 24V originate?

One side question, I used to have a print-out of all the diagnostic alarms and their drop numbers but it has mysteriously disappeared. For every drop number it had the alarm title and suggestions for what to look for and where to fix the problem... about a sentence or two about possible reason why the alarm ocurred. It was a text document and it was somewhat helpful in troubleshooting at times. Does anyone know where I person could find that document again? I found another one in our files that was similar in appearance that dealt with calibrating the GMV. I don't know if it's a file on the <I> or if it was downloaded from GE at one time or another. It would be nice to find a copy again if anyone has any knowledge of the document I'm referring too.

Thanks a bunch.
 
Sometimes due to heavy currents caused by short circuits especially on the 125VDC solenoid circuits, the terminal board prints get burned and some kind of Varistors get damaged causing a low resistance towards common ground. It maybe worth removing the terminal board and inspecting the printed circuit side of the board as well as the MOVs.

It might also be worth checking your power supply board for same symptoms/signs as above.
 
Sorry; I'm not clear. Have the J01 and J02 alarms cleared?

The ground you described is not a solid ground, and is probably indicative of some kind of moisture; most of these "soft" grounds like this are. (I call a "soft ground" a voltage imbalance where one leg of the DC supply is not 0 VDC with respect to ground.) If the solenoid that failed was a DC solenoid powered by 125 VDC from the <CD> core, it's likely that some other components were damaged, as well, and that might be part of the problem.

I've seen cards fail that are installed after one is damaged but before the field problem that caused the first card to be damaged is resolved. In other words, if the field problem still existed when the new card was installed, it sometimes gets damaged and once the field problem gets resolved it's necessary to replace the card again. Again, that could be the case if the solenoid was powered through the Mark V/<CD>.

I'm not very trusting of DIAGC information, but have you used DIAGC to look at the TCCA mA inputs to see what might be happening? What mA inputs are out of limits? Anything from the Water Injection skid? Have you verified the 4-20 mA inputs are okay?

The three battery-related Process Alarms you listed in your first email are from contact inputs; from some battery charger? I ask because usually the battery supply ground fault and the low DC supply voltage detection is done in the Mark V. And, the third alarm, the AC power failure is usually from a battery charger alarm output. It's just unusual to see a battery charger annunciating a ground alarm and low battery voltage with contact outputs (contact inputs to the Mark V). So, if the Mark V isn't reporting a ground (usually signal name L64D or something similar) and isn't complaining about a low battery supply voltage, then one might wonder if something in the battery charger didn't get zapped with the solenoid failure.

It's also possible that the DTBA card is damaged.
 
There are usually two files in the F:\Unitn directroy called HELP_QD.DAT and HELP_BD.DAT which contain explanations about the <Q> Diaganostic Alarms and <B>(meaning <C> ) Diagnostic Alarms.

The low voltage power supplies can be traced from <Q>TCPS Loc.5 card. If you have a Mark V Application manual this can be found on sheet D55 of Appendix D.

Good luck
 
The 24 VDC is the supply power for non self-powered analog (4-20ma) inputs.

The help file you seek might be HELP_QD.DAT located in your unit folder.

I would also recommend locating geh-5980 Mark V Maintenance Manual and geh-6195 Mark V Application Manual. After locating these manuals, the instructions for removing jumpers on <CD> core will allow the isolation of several digital inputs without lifting the wires. The manuals will also describe the test points to measure the power supplies with a VOM during your ground fault analysis. Diagnostic counter screen cannot be fully trusted for accuracy.

Pond and Lucier (http:\\www.pondlucier.com) also has a turbine tips section which contains a 3 part series on basic ground troubleshooting for the Mark V turbine controller.
 
Thanks for all the help so far.

J01/J02 alarms have not cleared. Also still have that Bat Ref signal failure (Plug JQ) alarm.

The mA inputs with alarms are those that are internally powered via the MKV. All on the TCCA/TCCB. They show 0mA input.

The 24V for these mA inputs originates in the <R> power supply??

I'm starting to wonder if the CTBA is causing some of this?

I do not have the help file as mentioned above on either of our <I>'s.
 
>>>UPDATE!<<<

I found the culprit to my remaining alarms. There was a blown fuse in the TCPS <C>, FU1. Replaced fuse and all but a handful alarms cleared.

The last few alarms are "mA inputs out of range" and they are terminated on the CTBA board. These inputs are self-powered but each have their own separate power supplies, so I'm still wondering if this is the CTBA board causing problems or not? The rest of the inputs on CTBA are active but haven't verified if the analog outputs are working
 
If the mA inputs are connected to <C>, the power originates from the <C> TCPS card in Loc. 5 of the <C> processor. I was asking specifically which mA inputs are not reading, and if any of them were from the Water Inj. Skid, since that's where the "toasted relay" was found.

Why are you asking about the CTBA? It could be a problem, since all the <C> 4-20 mA inputs are connected to it; do you have some reason to suspect it? If DIAGC reports there is no positive 24 VDC from <C>, then that's a good place to start checking for those alarms..

Have you check the fuses on the TCPS in <C>? Usually, it's necessary to remove the card to check all the fuses; it's very difficult to see a couple of the fuses if the card is in the processor. The fuse locations are shown on the card drawings in the plastic pockets on the backside of the <C> processor door.

Are you using the Signal Flow Diagrams in Appendix D of the Mark V Application Manual, GEH-6195, to follow signals from TB to I/O card, or vice versa?

Have you used a voltmeter to check the mA input terminals on CTBA for power?

It sure sounds like the TCDA card you installed may also have been damaged. You haven't provided any information about the three battery charger-related alarms from the previous response. If those three alarms are indeed coming from a single device like the battery charger, then usually there's a single contact input "common" wire (wire no. (107)) used for multiple signals. Have you checked to see if there's power on the (107) wire in the battery charger?

Another possibilty is that the "Berg" jumper for the contact input "bus" on the DTBA card is not installed; have you made sure all the jumpers on the DTBA are installed and the wires you removed were put back where they belong? (We're not there to know what's been done or how it was done; we're just asking to be sure!).
 
>>>>UPDATE #2!<<<

Replaced the TCCA <C> card today and all systems go.

BTW, the maintenance crew dissembled the water injection block valve that I suspected caused this problem and found that it had come apart internally and would not let the valve move when the solenoid was energized. Apparently something had unthreaded which allowed the spring to pop off inside and bind the valve stem, restricting it from opening. They also took the other block valve apart and inspected it but everything looked good and tight.

I appreciate all the suggestions and help throughout this ordeal. The only thing I wished was that this forum was more "real-time" so that information could flow much more quickly with the ability to make edits if mistakes are made. This would especially be helpful when time is an issue and help is needed urgently.

Thanks again!
 
If one doesn't have much experience with troubleshooting Mark Vs and doesn't want to call in an experienced person (and pay for the privilege of their company!), it's the next best thing since sliced bread.

I've always heard "any port in a storm is a good port."

I'm always afraid to ask, "Did you check the fuses?" (Some people take offense at such simplistic troubleshooting questions, and yet, sometimes it's the right question. Win some, lose some.)

Other people have wished for "avatars" so that posters can put information about their site and their experience; still others have wished for the ability to post drawings or pictures or files.

If wishes were horses, I'd be eternally shovelling manure!

I'm still unclear how a burned-up solenoid can cause a problem with analog inputs on the <C> core.

But, if it's working, all is golden.

As one of our earlier responders used to say: Feedback is our most important contribution! So, thanks for the updates and feedback. It really is what makes this forum useful, being able to see what works and what doesn't when troubleshooting.

Don't be a stranger!
 
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