TP-5606 6/02 Controller Troubleshooting 5-5
Three-Phase Generator
Sequence of Operation
Starting
Preheating—Preheating of the air heater in the diesel
engine is initiated by rocking the start/stop switch on the
control panel to the STOP/PREHEAT position for the
time period specified in Section 2. This action energizes
the AH relay. As a result, normally open contacts of the
AH relay close to energize the air heater.
At the end of the specified time period, the start/stop
switch is released or switched out of the
STOP/PREHEAT position. Either of these actions
opens the ground path to the AH relay, de-energizing the
AH relay and the air heater.
Engine Start-up—The engine is started after air heater
preheating by rocking the start/stop switch on the
control panel to the START position. At this point, the
10-ampere fuse must be good. If not, power to the
starting circuits is interrupted and none of the following
actions described in this section occur.
Setting the Start/Stop switch to the START position
energizes the K2 relay (LED2 lights). As a result,
normally open contacts of K2 close to energize the K3
relay, the K25 relay, and the FP (Fuel Pump) motor.
Energizing the K3 relay (LED3 lights) causes a set of
normally open contacts to close and energize relay K20.
A set of normally open contacts of K20 then close to
energize the S solenoid (Starter Solenoid). As a result,
normally open contacts of the S relay close to energize
the M (starter) motor and the starter motor gear engages
the ring gear on the engine flywheel to begin cranking
the engine. At the same time, the power supplied to the
starter motor also energizes the pull-in coil of the FS
(Fuel Solenoid).
Energizing the K25 relay closes a set of normally open
contacts to energize the hold coil of the fuel solenoid to
complete the conditions necessary for engine start-up.
Releasing the Start/Stop switch allows the switch to
return to its neutral position. If the switch is released
before the engine starts (the K1 relay is still
de-energized), the K2 relay de-energizes. The normally
open contacts of the K2 relay then open to interrupt
power to the engine start-up circuits. As a result the K3
relay, the K25 relay, the K20 relay, the Fuel Pump, the
Fuel Solenoid, and the Starter Solenoid all de-energize
to cease start-up of the engine.
TO REMAINING
CIRCUITS
12 VDC
AIR HEATER
AH
M
FS
S
10 A.
K25
FP
10 A.
START
STOP/
PREHEAT
K1C
K1D
K1E
K2
K3
K3
K2
K20
S
B.C.
ALT
LED3
LED2
AH
K25
K4
K20
Figure 5-5. Three-Phase Generator Sequence
of Operation, Starting
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