TM-9-2350-311-20-1 Maintenance Manual for Volume 1 M109 Hull Download
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1-17 EQUIPMENT OPERATION AND DESCRIPTION — CONTINUED 1-17.6 Electrical System The M109A2/M109A3/M109A4/Ml109A5 Howitzers’ electrical system consists of: a. b. c. d. e. f. g. Batteries (1) — four 12-V connected in series and parallel to deliver 24 Vdc (nominal) to the master relay (2). Master relay (2) — delivers electrical power (24 Vdc [nominal]) to operating systems when the MASTER switch (3) is on. The master relay delivers power directly to the slip ring contact board (TM 9-2350-311-20-2), engine starter (4), slave start receptacle (5) (M109A3 shown), circuit breaker board (6) (M109A2/M109A3 shown), and cab (slip ring segment board) (TM 9-2350-31 1-20-2). MASTER switch (3) — when activated, draws 24 Vdc (nominal) from the battery through the master relay (2) to operate the M109A2/M109A3/M109A4/M109A5 Howitzers’ electrical systems. With the MASTER switch ON, systems can be operated without running the engine. Alternator (7) — engine driven and delivers 24 Vac (nominal) to the rectifier (8). Rectifier (8) — full-wave, bridge rectifier converts the generator ac voltage to dc voltage which is in turn delivered to the voltage regulator (9). Voltage regulator (9) — controls the delivery of 24 Vdc (nominal) to the vehicle operating systems through the master relay (2) and also acts as a recharger for the batteries when the engine is operating. External power receptacle (10) — provides vehicle auxiliary power from an external source. 1-26 TM 9-2350-311-20-1