TM 9-6115-604-34
NAVFAC P-8-633-34
(1)
Tripping low fuel level alarm relay Al OK5 energizes low fuel level time delay shutdown relay K23. After a
preset time delay (normally 35 minutes), relay K23 will energize fault shutdown relays K20A and K20B.
Relays K20A and K20B will shut down the engine and disconnect generator G1 from the load, as described
in step h (2), above. Theoretically a generator set shutdown will not occur because the operator will
replenish the generator set fuel supply and reset the alarm circuit before the time delay (normally 35
minutes) elapses. Note that if the operator replenishes the fuel supply, but fails to reset the alarm circuit
via ANNUNCIATOR RESET pushbutton S1 2, low fuel level time delay relay K23 will still time out and
cause a generator set shutdown. The operator will not be able to reset the alarm circuit before replenishing
the fuel, but failure to reset the circuit after refueling will result in a shutdown. The purpose of this circuit is
to back up the fuel transfer system circuit. I the fuel transfer system circuit is operational and set to AUTO,
low fuel level alarm relay L1 OK5 will not trip if the generator set is connected to an adequate external fuel
supply.
(2)
Tripping high fuel level alarm relay Al OK6 will energize high fuel level fault slave relay K5. Relay K5 will
open its normally dosed contacts to deenergize fuel pump contractor K1 3. Contactor K1 3 will open its
normally dosed contacts to cut-off 1 20 V ac from fuel transfer solenoid L1 02 and fuel transfer pump
contactor K1 06. Contactor K1 06 will deenergize, cutting off 240 V ac from fuel transfer pump motor B1
02. Solenoid valve L1 02, deenergized, will dose to block the fuel inlet line, preventing any more fuel from
entering the generator set fuel tank The primary purpose of this protection circuit is to prevent overfilling of
the generator set fuel tank by gravity feed (siphoning) from the external fuel supply. Secondarily, the
circuit guards against fuel transfer system "runaway" which could occur if high fuel level float switch FL2
failed to open upon a high fuel level condition.
j.
Remote Indicator Circuits. Two of the alarm system self-latching relays have additional contact sets used to
annunciate faults on the remote control module control panel. These contact sets function as follows: (1)
Tripping high coolant temperature alarm relay Al 0K3 will connect battery positive, through the remote control
cable assembly, to the RCM viaJ26-q. The voltage is applied to HIGH WATERTEMP indicator light DS23.
Ground return to the generator set is via J26-h.
(2)
Tripping low oil pressure alarm relay Ai1K2 will connect battery positive, through the remote control cable
assembly, to the RCM via J26-AC. The voltage is applied to indicator light DS2, LOW OIL PRESSURE.
Ground return to the generator set is via J26-h.
10-2. ANNUNCIATOR ALARM SYSTEM REPAIR . Repair of the annunciator alarm system consists of replacing
defective elements in the annunciator alarm system circuit and repairing annunciator box A9 in the event it should fail.
a.
Relays. Relays are the most common component of the annunciator alarm system. Refer to Chapter 5, Section
VI, for testing and replacement of generator set relays.
b.
Wiring. Defective wires and incorrect wiring will result in annunciator alarm system failures. When tracing wiring
to detect failures, refer to FO-1, DC Electrical Schematic; FO-2, AC Electrical Schematic; FO-3, Remote Control
Module AC and DC Schematic; and FO-4 through FO-39, the generator set and RCM wiring diagrams.
c.
Annunciator Panel A9 Repair. When troubleshooting indicates an annunciator panel A9 failure, refer to Figure
10-2 and accomplish repair as follows:
(1)
To replace defective lampbulb (2), remove lampsocket (1) from back of the printed circuit board (5),
remove and discard lampbulb (2), install good lampbulb in lampsocket (1), and install lampsocket (1) into
back of printed circuit board (5).
(2)
To replace or change nameplates (4), proceed as follows: (a) Remove screws (3) from comers of printed
circuit board (5).
(a)
Open printed circuit board (5) on its hinge, like a door.
(b)
Remove and replace nameplates (4), as required.
(c)
Close printed circuit board (5) on its hinge, like a door.
(d)
Install screws (3) in comers of printed circuit board (5).
10-3
