NATIONAL ALUMINIUM COMPANY LIMITED - Rites

All audio visual annunciation of following parameters should be incorporated in the HMI of
PLC.
(a) 33 kV Breaker Trip (Group wise for each board)
(b) 415 V MCC Breaker Trip (MCC wise)
(c) Bus under voltage for each LT MCC
(d) Following group wise annunci annunciation ation shall be provided for transformers :
(i) Buchholz alarm
(ii) Winding/oil temperature high alarm
(iii) Oil level low alarm
(iv) Buchholz trip
(v) Winding/oil temperature high trip
(e) A.C Control Supply failure.
(f) D.C. Control Supply failure.
(g) Annunciation supply failure.
(h) Both CPU fail
(i) Stand by CPU in service
(j) LT motor overload tripped (Group).
(k) ) Belt sway switch operated (Group)
(l) ) Pull cord switch operated (Group)
(m) ) Zero speed switch operated. (Group)
(n) ) Chute plugged (Group)
(o) Wagon rake arrival.
(p) ) Wagon Tippler tripped (group)
(q) Apron feeder.
(r)Dust Dust suppression/service water system faults and trips (system wise)
(s) ) Water level low in tanks (group)
(t) ) Oil temperature of fluid coupling high
(u) 20% spare windows
For identification of the fault for a particular conveyor or equipment, status indication
against that conveyor / equipment in the mimic will start fast flickering and the annunciation
window will be blinking against that particular fault. In addition, a buzzer (alarm) will also
start tart sounding. After acknowledgement of the fault, the buzzer will stop, but the fast
flickering on the mimic and the steady glow on the annunciation window will continue until
the fault is cleared and the Reset push button is pressed. When the fault is cl cleared and the
Reset push button is pressed, the status indication of that conveyor / equipment on the
mimic will start slow blinking if it is on selected path otherwise it will go off and the steady
glow in the annunciation window will go off. However, pre pressing ssing of the Reset push button
before clearance of the fault, will have no effect on the lamps.
At the time of a fault, the faulty conveyor / equipment, as well as the preceding conveyors /
equipment in the interlock sequence, will stop except H.T. motors for which only scoop
coupling will be disengaged and motor will continue to run for process fault. In case of
motor fault, H.T. motor will trip but the succeeding conveyors / equipment will continue to
run. The status indication against the preceding conv conveyors eyors / equipment will start slow
Technical Specification:Sec-4,System System Parameters, Operation & Control Philosophy
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