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MARK V (P) Core
Need information about MARK V <P> - Protective Core and its TCEA system working structure and related logic
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<P> - Protective Core provide emergency overspeed protection, gas turbine flame detection, the automatic synchronization signal, and testing of overspeed trips for certain applications, but i need more information about the core.


Do you mean the manual? or additional document about the protection core?

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All of the functions of the <P> core are covered in the Mark V Applications Manual, GEH-6195.

Yes, it does emergency overspeed (ALWAYS--even if the unit has a mechanical overspeed bolt, the emergency overspeed is ALWAYS functioning), flame detection, synchronization functions (it accepts the PT (running and bus) inputs, and does the AUTO synch function; the MAN synch function is accomplished in <Q>), AND it also does rate of change of speed detection. So, if the speed signal inputs to the <P> core are intermittent or changing very quickly for some reason, it will also initiate a turbine trip.

The <P> core also contains the synchronizing relays, even the MAN synch check relay (which is driven by <Q> sequencing) is contained in the <P> core. The relay contact which is connected to the generator breaker close circuit is contained on the TCTG card in the <P> core.

The <P> core drives the ETRs (Emergency Trip Relays) on the TCTG card (for a GE-design heavy duty gas turbine), which control the application of the positive leg of the 125 VDC to the trip solenoid(s). Any trip function (emergency overspeed; rate of change of speed exceedance) will cause the ETRs to be dropped out.

The ETRs have an interlock with L4 in the sequencing, via L4_XTP. If L4 goes to a logic "0" the ETRs will also be tripped. (L4 in each control processor of <Q> drives a PTR (Primary Trip Relay)--so there are three sets of PTRs, also mounted on the TCTG in <P>.) The PTRs control the negative leg of the 125 VDC which is connected to the trip solenoid(s).

You should also refer to Appendix D of GEH-6195 for the cards which are contained, or could be contained, in <P> for more information about signal connection (inputs and outputs, and PTRs and ETRs and synch relays and such).

The E-Stop push-button(s) on the Mark V control panel door and possibly elsewhere are also connected to the <P> core.

If you have some specific questions or problems with the <P> core, please--ask them for more specific help. And, refer to GEH-6195 for more information, but not ALL information. (GE documentation can be sorely lacking at times.) We have several people with some good knowledge and experience--if we know what you're looking for.

Hope this helps!

Thank you for your reply sir. its very useful for me.

Thank you for your response, I am new for GT just started to study

1. Need clarity about relationship b/w P core and Q cores.

1. a) Particular inputs are connected to P core and p core communicating to Q (Q giving output (trip/healthy) based on CSP ). Q directly communicating to trip board ---(Y/N)?

2. How communication working b/w P core and Q cores

3. There is any hardware setting for loss of flame in p core (like over speed)?

4. In mark V we have TMR (Q) and 3 TECA cards in P core for redundant, but in P core have only one trip board. why redundant card not installed for trip board (which is giving trip signal to hyd oil system)?

1 out of 1 members thought this post was helpful...

vijaycontrol,

>1. Need clarity about relationship b/w P core and Q cores.

<P> is the Protective core, and <Q> (<R>, <S> & <T>) are the redundant control processors. To my knowledge, there is no "control" done in the <P> core, with the possible exception of the auto synchronization function. The intent of the <P> core was to provide a completely independent method for monitoring and detecting an overspeed condition and tripping the turbine independently of the <Q> primary electrical/electronic overspeed detection/protection. That's the primary "protective" function of the <P> core. There are several standards around the world which require at least two independent methods of detecting overspeed and tripping the turbine in a turbine control system. And, the <P> core meets all of these requirements.

The designers of the Mark V had to add flame detection to the <P> core, because of other considerations. (One of the most important things I learned about designing and building products is: Engineering is a series of compromises. That's what there's no perfect automobile, or perfect anything (not even iPhone is perfect).) Flame detection required a separate 335 VDC power supply (for the infrared flame detectors used at the time the Mark V was designed) and the only place to "elegantly" put it was in the <P> core.

<Q> is for control and protection. Speed control, which requires fuel control, which requires overtemperature protection. Also, there's all the other protection functions--oil pressure, loss of flame (which is done in <Q> using the inputs to <P>), vibration, overspeed, etc. And, <Q> also provides the manual synchronization function, if used (and most generator-drive applications do use both the manual- and auto synch functions of the Mark V).

>1. a) Particular inputs are connected to P core and p core
>communicating to Q (Q giving output (trip/healthy) based on
>CSP ). Q directly communicating to trip board ---(Y/N)?

You need to look at the TCTG card depiction in Appendix D of GEH-6195 to understand exactly how tripping is accomplished. It's done with Primary Trip Relays (PTRs) and Emergency Trip Relays (ETRs), and BOTH use a two-out-of-three hardware voting scheme. <R> has it's own PTRs, <S> has its own PTRs, and <T> has its own PTRs--and again, they are physically connected so that two out of the three have to "agree" in order for the negative leg of the 125 VDC to be applied to the trip solenoid to allow the turbine to run.

<X> (the TCEA in Loc. 1 of <P>) has its own ETR, and so does <Y> (the TCEA in Loc. 3 of <P>), and so does <Z> (the TCEA in Loc. 5 of <P>). They are also physically connected so that two out of three have to "agree" in order for the positive leg of the 125 VDC to be applied to the trip solenoid to allow the turbine to run.

<X>, <Y> & <Z> are also collectively called <W>. They communicate directly to the ETRs on the TCTG (in Loc. 4 of <P>). <R> communicates to its PTR via its IONET (through <X>). <S> communicates to its PTR via its IONET (through <Y>). <T> communicates to its PTR via its IONET (through <Z>).

>2. How communication working b/w P core and Q cores

Via each control processor's IONET. <R> has an IONET that connects from its TCQC to the TCEA in Loc. 1 (<X>) of <P>, then to the TCDA in Loc. 1 of <QD1>, and if so equipped, to the TCDA in Loc. 1 of <QD2>. <S> has an IONET that connects from its TCQC to the TCEA in Loc. 3 (<Y>) of <P>, then to the TCDA in Loc. 2 of <QD1>, and if so equipped, to the TCDA in Loc. 2 of <QD2>. <T> has an IONET that connects from its TCQC to the TCEA in Loc. 5 (<Z>) of <P>, then to the TCDA in Loc. 3 of <QD1>, and if so equipped, to the TCDA in Loc. 3 of <QD2>.

>3. There is any hardware setting for loss of flame in p core
>(like over speed)?

Sort of. The number of counts (in other words, the intensity) at which flame is determined to exist and at which it is determined to be lost, is or can be specified in the I/O Configuration for the TCEA cards in <P>. BUT, the actual "voting" on whether or not flame exists is done in the CSP running in <Q> (using the inputs to <P>, via the IONETs between the control processors and the protective processors).

>4. In mark V we have TMR (Q) and 3 TECA cards in P core for
>redundant, but in P core have only one trip board. why
>redundant card not installed for trip board (which is giving
>trip signal to hyd oil system)?

Again, the trip card for gas turbines is the TCTG card, and you need to refer to the Signal Flow Diagrams for the TCTG card in Appendix D or GEH-6195 for specifics. But, both the PTRs and the ETRs (and, there are individual PTRs and ETRs for both <Q> and <P> (<R>, <S> & <T>; and <X>, <Y> & <Z>). So, there is redundancy--it's just on one board. No need for three--or six--boards; it would have been extremely difficult to connect them all to provide the necessary two out of three for both the PTRs and the ETRs. But, there is two out of three protection on the single trip card--for BOTH <Q> and <P>.

By the way, the synch relays are located on the TCTG, also. A convenient place for them, too.

Hope this helps!

thank you for your valuable reply sir.