Hello every one
I have question about TMR Analoge output 4-20ma voting in MARk6
Control system .

(Analoge input tmr voting, Discrete input/output , analogue out for servo ....its ok for me )

in the figure attached bellow:

the manual speak about send three current . and read the voltage feedback . To select the voted value. ( Hardware voting).
But how can send three current in same time to the load ...(the current will be 3 times .
So can any one have explanation for this?
Regards

 

Well, this isn't about Mark* VI--it's the Mark* VIe.

Multiple I/ONet packs (I/O Packs) can send signals to a single terminal board (in this case the TBAI from you scan snippets above). And there is circuitry on the TBAI which "chooses" which of the signals (two for DUAL Redundant or three for TMR (and NOT all 4-20 mA outputs are redundant) gets passed through to the device(s) connected to the terminals of the output card. And, to my knowledge, GE doesn't always provide details or schematics of precisely how all of their circuits and schemes actually work.

I think a better reference document would be GEH-6721, Vol. II. And, you need not to focus on the I/O Pack(s) but also the I/O terminal board the I/O Pack(s) is(are) connected to. If the output in question is a triple redundant output there will be three I/O Packs on the I/O terminal board (usually a TBAI) and, again, circuitry on the I/O terminal board will "choose" which I/O Pack's output is connected to the output terminals. (And, usually, GE doesn't use active components on terminal boards, but that seems to be changing lately (active components being integrated circuits like chips, as opposed to passive components like resistors and capacitors and inductors and optical isolators, etc.).

Again, there's not a lot usually written about the specifics of these control schemes. And, if you're experiencing a problem, it's probably best to try to describe the problem here and see if someone can help you with troubleshooting and resolving it. The manuals can be helpful, but when you get down to the component level they usually aren't very helpful.

In my experience, when this works it works very well--and when it doesn't work it's very difficult to troubleshoot and resolve. BUT, there are usually Diagnostic Alarms which can help (in some cases....) to try to resolve the problem. Which is usually replacing I/O Pack(s) and/or the I/O terminal board--PRESUMING the device that is being driven is not experiencing its own problems causing the Mark* VIe outputs to respond with odd outputs.... As hard as it is to believe--MOST problems of this type with GE-design heavy duty gas turbine control systems are the result of wiring problems or field devices.

AND, since you took the liberty of showing a YAIC I/O pack (SIL rated) you might also have passive or active devices in the output circuits which limit energy to prevent explosions--and it's not uncommon for them to fail intermittently before failing completely and causing nuisance and difficult problems.

 

Well, this isn't about Mark* VI--it's the Mark* VIe.

Multiple I/ONet packs (I/O Packs) can send signals to a single terminal board (in this case the TBAI from you scan snippets above). And there is circuitry on the TBAI which "chooses" which of the signals (two for DUAL Redundant or three for TMR (and NOT all 4-20 mA outputs are redundant) gets passed through to the device(s) connected to the terminals of the output card. And, to my knowledge, GE doesn't always provide details or schematics of precisely how all of their circuits and schemes actually work.

I think a better reference document would be GEH-6721, Vol. II. And, you need not to focus on the I/O Pack(s) but also the I/O terminal board the I/O Pack(s) is(are) connected to. If the output in question is a triple redundant output there will be three I/O Packs on the I/O terminal board (usually a TBAI) and, again, circuitry on the I/O terminal board will "choose" which I/O Pack's output is connected to the output terminals. (And, usually, GE doesn't use active components on terminal boards, but that seems to be changing lately (active components being integrated circuits like chips, as opposed to passive components like resistors and capacitors and inductors and optical isolators, etc.).

Again, there's not a lot usually written about the specifics of these control schemes. And, if you're experiencing a problem, it's probably best to try to describe the problem here and see if someone can help you with troubleshooting and resolving it. The manuals can be helpful, but when you get down to the component level they usually aren't very helpful.

In my experience, when this works it works very well--and when it doesn't work it's very difficult to troubleshoot and resolve. BUT, there are usually Diagnostic Alarms which can help (in some cases....) to try to resolve the problem. Which is usually replacing I/O Pack(s) and/or the I/O terminal board--PRESUMING the device that is being driven is not experiencing its own problems causing the Mark* VIe outputs to respond with odd outputs.... As hard as it is to believe--MOST problems of this type with GE-design heavy duty gas turbine control systems are the result of wiring problems or field devices.

AND, since you took the liberty of showing a YAIC I/O pack (SIL rated) you might also have passive or active devices in the output circuits which limit energy to prevent explosions--and it's not uncommon for them to fail intermittently before failing completely and causing nuisance and difficult problems.

Thanks a lot for fast response
Really we don't have problem in our system.
But i want to understand how its work (just for more information).
and also i think GE
Thanks again for your answer .
Regards

Well, this isn't about Mark* VI--it's the Mark* VIe.

Multiple I/ONet packs (I/O Packs) can send signals to a single terminal board (in this case the TBAI from you scan snippets above). And there is circuitry on the TBAI which "chooses" which of the signals (two for DUAL Redundant or three for TMR (and NOT all 4-20 mA outputs are redundant) gets passed through to the device(s) connected to the terminals of the output card. And, to my knowledge, GE doesn't always provide details or schematics of precisely how all of their circuits and schemes actually work.

I think a better reference document would be GEH-6721, Vol. II. And, you need not to focus on the I/O Pack(s) but also the I/O terminal board the I/O Pack(s) is(are) connected to. If the output in question is a triple redundant output there will be three I/O Packs on the I/O terminal board (usually a TBAI) and, again, circuitry on the I/O terminal board will "choose" which I/O Pack's output is connected to the output terminals. (And, usually, GE doesn't use active components on terminal boards, but that seems to be changing lately (active components being integrated circuits like chips, as opposed to passive components like resistors and capacitors and inductors and optical isolators, etc.).

Again, there's not a lot usually written about the specifics of these control schemes. And, if you're experiencing a problem, it's probably best to try to describe the problem here and see if someone can help you with troubleshooting and resolving it. The manuals can be helpful, but when you get down to the component level they usually aren't very helpful.

In my experience, when this works it works very well--and when it doesn't work it's very difficult to troubleshoot and resolve. BUT, there are usually Diagnostic Alarms which can help (in some cases....) to try to resolve the problem. Which is usually replacing I/O Pack(s) and/or the I/O terminal board--PRESUMING the device that is being driven is not experiencing its own problems causing the Mark* VIe outputs to respond with odd outputs.... As hard as it is to believe--MOST problems of this type with GE-design heavy duty gas turbine control systems are the result of wiring problems or field devices.

AND, since you took the liberty of showing a YAIC I/O pack (SIL rated) you might also have passive or active devices in the output circuits which limit energy to prevent explosions--and it's not uncommon for them to fail intermittently before failing completely and causing nuisance and difficult problems.

Thanks a lot for fast response
Really we don't have problem in our system.
But i wanted to understand how its work.
Also i think there is active component
In terminal board.
In general thanks alot for your answer
Regards

 

No experience with any of this equipment, but SIL logic has some common traits.

The relay logic shows 3 DO channels, R, S and T
Each channel drives its own internal driver.
Two of the three DO channels have to be active to trigger the final output.

For instance, if channel S is not active, then channel R will drive the KR coil, channel T will drive KT coil and the KT and KR contacts will then provide an active relay output. 2oo3 logic.

SIL rated Analog Outputs typically sense the current value for a plus/minus tolerance. On another system, I've seen a SIL 2 A/O that required an AI that would monitor the current through the load. The configuration would not 'compile' unless the logic included a designated AI. The AO would 'fault' if the AI's value did not match the AO's value within a fairly tight tolerance band.

Your diagram shows two current sense resistors, one called Current Feedback that senses the current requlator output current and a second current sense resistor on the TBAI terminal board that is sensed as "Total Current Feedback". Exactly what the logic is in the magic current regulator function block is not revealed, but the idea is to make sure that the AO is functioning through monitored feedback.

 

david2 has an excellent response. Although, the analog function is a little different in my experience.

Each core has inputs and outputs to a servo that has 3 coils and each core has access to a 3 lvdt i.e. position feedback.

The cores RST share access to the data and vote.

I do not know if the Mark VI has prevote data screen available. However, on the prevote data screen on a MarkV one can actually see how it works.

For instance; we are watching gas valve one and the valve needs 12ma to maintain its position. In prevote screen you will see that R is providing 6ma and T is providing 6ma. S core is simply awaiting for something to go wrong and then it steps in to provide current.

Do not assume that it is always R and T with S core ready to step in. It is random. Hopefully, this helps. Do not assume that every triple redundant sensors are the same. Some of the TMR stuff is on landed on terminal board to R core which is shared via ribbon cables.

Then one moves on to P Core.

Hopefully, I have shared the enough to help one learn how it works.