Thermo King SGCO 3000, Руководство пользователя

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Alternator Operation and Diagnosis
116
Alternator Function
Starting Excitation
The initial excitation for the alternator is supplied
by the SG+ Controller approximately 15 seconds
after the engine starts. The controller energizes
wire F1, which sends the current through the
exciter field to build voltage in the stator
windings. The current then travels through wire
F2 where the circuit is completed to chassis
ground.
NOTE: When the Delayed Cold Start feature is
set to ON, the exciter field is not energized until
the engine temperature rises to 32 C (90 F).
Running Excitation and Control
The magnetic field that was formed in the exciter
field stator winding by current from the controller
induces a current in the exciter rotating winding.
This current is changed from three-phase ac to dc
by the rotating rectifier. The dc current is
transferred to the main alternator field winding.
The main alternator field now becomes magnetic.
The magnetic field formed in the main field
winding now induces a voltage in the alternator
stator windings. This voltage is either 230 Vac or
460 Vac, 3-phase, depending on stator
connections.
It is sent out of the alternator stator leads to the
power plug and then to the load. The controller is
tapped into the alternator stator leads. The
controller reads the alternator output voltage and
steps this voltage down to around 12 Vac (1/20th
of output voltage). This current is rectified to dc
current and is used to charge the battery and
energize the exciter field. The controller monitors
the alternator output voltage and adjusts the
output to the exciter field as necessary to maintain
the alternator output at the correct voltage.
Battery Charging
The unit battery is recharged by the alternator
through the controller, which performs the
functions of a voltage regulator and rectifier. Fuse
SI2 (30 amps) protects the battery charger output
circuit.
Overload Shutdown
The overload shutdown is provided by the
controller.
If an overload condition becomes more than
temporary, the reduction in alternator output
voltage due to the overload causes the controller
to increase field current through wire F2. The
controller senses the overload current and then
de-energizes the fuel solenoid to stop the engine.
If the controller shuts down unit operation, it
indicates one of the following:
1. There is a malfunction in the load causing the
load to fail to start or to draw single phase
current.
2. The engine speed or power is low due to
improper speed adjustment, fuel supply
problems or other mechanical conditions
while the generator is supplying motor starting
current to the load.
3. Internal component failure in the excitation
control system, resulting in excessive field
current. This includes possible malfunction of
protective elements in the excitation control.
4. Failure in the alternator rotating elements
(exciter armature, rotating diode assemblies or
main field) can cause the regulator to supply
excessive exciter field current.
5. Engine shutdown on low engine oil level, low
oil pressure or high water temperature.