Composite Trip was inevitable. It came all of a sudden and stayed there. What we got was positive supply not being extended to Trip Solenoids even after forcing Cross Trip signal (L4_XTP) to 0. Finally it came to us as a revelation that the problem was because of one of the 7 Trip contacts which may be connected directly to TREG Board for Emergency tripping. These contacts are to be Normally Closed so that positive supply can get extended to the terminals. One such contact of Generator Class-A trip (l86tgt1) was connected to TREG but it was Normally Open and the day it was connected our problem of Composite Trip (L5Cmpst_trp1) started.
The possible remedy was either use a NC contact of that trip or shift it to ordinary Contact Input terminal (TBCI). Since NC contact was not available at Generator Relay Panel, it was shifted to TBCI. Thus we could get rid of Composite Trip.
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