Figure 1-6 A−C Generator Circuit Diagram - Carrier TRANSICOLD 69UG15 Series Operation And Service

1.4 ENGINE SCREW THREADS
All threads used on the engine are metric except for the
oil drain plug, which is American Standard Pipe Thread
(NPT).
1.5 ALTERNATING CURRENT GENERATOR
1.5.1 Principle of Operation
The Marathon Alternator Company (Lima) brushless
alternating current generator (see Figure 1-2, item 11) is
a self−regulated, rotating field synchronous unit. The
generator stator and exciter stator are combined in a
common housing. The generator field, exciter rotor, and
rotating rectifier assembly are mounted on a common
shaft. The output of the exciter rotor is applied to the
generator field winding through a rotating, full−wave
bridge, silicon rectifier unit.
All connections between the exciter stator windings and
generator stator windings are internal within the stator
housing. Only the output power leads are connected at
the terminal box, which is located on top of the
generator.
FIELD
STATOR
GENERATOR
RECTIFIER
ASSEMBLY
Figure 1-6 A−C Generator Circuit Diagram
T-343
SHUNT
SERIES
STATOR
L
O
A
D
ROTOR
EXCITER
1.5.2 Alternating Current Generator Diagram
Figure 1-6 shows the internal schematic diagram of the
generator, exciter, and rectifier unit. The generator is a
three−phase unit, the exciter stator and exciter rotor
also have three−phase windings. A portion of the exciter
stator windings is connected across a tap on the
generator stator winding. This exciter shunt winding
provides the generator field excitation power required
for generator no−load voltage. Another portion of
exciter stator windings is connected in series with the
output of the generator and provides a compounding
excitation characteristic.
The rotor is, in effect, the secondary of a rotating current
transformer induction frequency converter. The exciter
rotor output voltage is applied to the generator field
windings by a three−phase, full wave rotating silicon
rectifier unit. The response time of the excitation system
is very fast as the exciter stator carries an alternating
current corresponding to the load current that appears
immediately on the exciter primary. An increase in load
current will cause an immediate increase in the exciter
secondary output voltage, which is rectified and applied
to the generator field windings. The inherent
compounding characteristics of the excitation system
provide excellent voltage regulation even under heavy
overload conditions.
1.6 BATTERY CHARGING SYSTEM
The solid state battery charger (see Figure 1-2) is
located to the left of the radiator. The charger is powered
by the generator, and this input is protected by a circuit
breaker located on the control panel. The battery
charger produces a tapered charge (25 amps
maximum) and is designed not to overcharge the
battery.
Observe proper polarity when installing the
battery or connecting a battery charger. The
negative battery
grounded. Reverse polarity may damage
the charging system. When charging the
battery in unit, isolate the battery by
disconnecting the negative battery terminal
first, then the positive. Once the battery has
been charged, connect the positive battery
terminal first, then the negative.
1−6
CAUTION
terminal must be