Generac Power Systems 53187 - Manual (Page 108)

SECTION 5.1
INTRODUCTION TO DC CONTROL SYSTEMS
1
PARTS
ENGINE ELECTRICAL SYSTEM
Operating Diagram- Type 1 DC Control System
See Figure 2, below. Operation of the Type 1 DC
control system may be briefly described as follows:
ENGINE SHUT DOWN:
1. Battery voltage is available to the normally-open
contacts of the starter contactor iSC), via Wire 13.
However, SC is de-energized and the circuit is open.
2.
Battery voltage is available to the normally-open
contacts of crank relay (CR1) and run relay (CR2), via
Wire 13, circuit breaker (CBS), and Wire 15. With CR1
and CR2 de-energized, the circuit is held open.
CRANKING:
Setting the start/stop switch to ’Start* closes the Wire
17 and CR1 circuit to ground. Crank relay (CR1) ener­
gizes and its contacts close to initiate the following:
a. Battery voltage is delivered to Terminal 1 of the
engine control circuit board, to turn the circuit board
on.
b. Wire 17A from circuit board Terminal 3 is con­
nected to ground. Circuit board action then delivers
a DC voltage to the starter contactor (SC) coil, via
Wire 56. SC energizes, its contacts close, and
battery power is delivered to the starter (S) via Wire
16. The engine cranks.
c. Circuit board action delivers a DC voltage to Wires
14. Run relay (CR2) energizes. An hourmeter is
turned on. A fuel pump (FP) and a fuel solenoid (FS)
are energized by Wire 14 power and the engine
starts.
RUNNING:
On startup, the start/stop switch is released. This
opens the CR1 circuit and that relay de-energizes to
terminate cranking. Relay CR2 remains energizes to
sustain operation.
SHUTDOWN:
Setting the start/stop switch to “Stop* closes the
Wire 18 circuit to ground. Circuit board action then
opens the DC circuit to Wire 14. The fuel solenoid (FS)
closes and the fuel pump (FP) shuts down. Fuel flow is
terminated and engine shutdown occurs.
CB3
CR1
CR2
f1
FP
FS
HM
HWT
LOP
S
sc
= 10 AMP CIRCUIT BREAKER
= CRANK RELAY
= RUN RELAY
= 14 AMP FUSE
= FUEL PUMP
c FUEL SOLENOID
B HOURMETER
= HIGH TEMP. SWITCH
B LOW OIL PRESSURE
SWITCH CB3^
- STARTER
= STARTER CONTACTOR ^
1 3
BATTERY
NEGO
"”"O hm '
-f-i
TO
FIELD
BOOST
AC FREQUENCY
ENGINE CONTROL HWfT
CIRCUIT BOARD
rh
Figure 2. Operating Diagram- Type 1 DC Control System
PAGE 5.1-2