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Updated Logic for LF Purge Isolation Valve Control

Proposed modifications to the existing logic for LF purge isolation valve control, including the addition of a time delay and the removal of unnecessary contacts.

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Updated Logic for LF Purge Isolation Valve Control

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  1. This is the “fix” logic that was initially sent from GE. I originally suggest to close the valve at the end of Warm-up, but they specified to initiate instrument air to the 20PL-3 valves at light-off…..which I am OK with……..However……goto next slide.

  2. I replied back……stating that I didn’t see a reason to include this group of contacts, since this logic is included in L20FLX or controlled by L20FLX (i.e. L4FP1)…….it’s like having 3 L20FLX normally-open contacts in a row in the same rung. I stated that I would rather minimize the additional logic to l20pl3c with just the time delay (L20FLX_TD)……..along with the conditions “not at FSNL” and “not in normal shutdown below FSNL”. In some site situations there are Lead/Lag fuel pump configurations, would rather see run status of fuel pump(s) then commands. See next 3 slides.

  3. I suggested to change the tag name of the signal L20FLX_TD to L20FLX_PL3 (that will be added for the time delay output), so that its designation relates to the logic it affects (l20pl3c)…..since there are other 20FLX time delay blocks in the logic (e.g. L20FLXZ).

  4. I suggested the Time Delay Constant for the L20FLX_PL3 Logic.

  5. I requested concurrence that it is permissible to incorporate the described logic shown above into the l20pl3c logic. I wanted to eliminate some of the contacts that made up the initial string of logic (e.g. L28FDX, L2TVX, etc……see slide 1), since L20FLX is made up of that particular string sequence in slide 1 and that l4fp1 is controlled by L20FLX. I wanted to see verification of LF pump(s) running (L52FP) instead of the command to the LF Pump (l4fp) .

  6. With GE not concurring with my suggestions………which I am very comfortable with the suggestions I made. I will have to leave it up to you now……You can use the initial logic that GE sent …..or you can use my position on the matter now, and that is to just add the L20FLX time-delay, with the L94X & L14HS normally-closed contacts (shown circled above) and you’ll be good for your next LF runs where the LF purge isolation valves will close off before you begin to accelerate to FSNL.

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