Generac Power Systems IM Series - Manual (Page 8)

OPERATIONAL ANALYSIS OF D-C CONTROL SYSTEM
Introduction
This section of your Manual is intended to familiarize the
reader with how the RV generator’s d-c control system
functions. The d-c control system provides the means to
obtain engine cranking, engine ignition and fuel flow, car­
buretor choking, field boost and battery charging. If
problems with any of these functions are encountered,
the technician must have a working knowledge of how the
system operates.
Circuit Condition- Engine Shut Down
A
With engine stopped, the circuit condition may be
described as follows:
1. Battery voltage is available to the normally-open
Starter Contactor (SC) contacts. The contacts are open
and the circuit is incomplete.
2. Battery voltage is available through a 15 amp Fuse (FI)
and to the normally open contacts of Control Relay (CR1).
These contacts are open and the circuit is incomplete.
3. Battery voltagte is available through Fuse (Ft), through
the normally-closed contacts of Control Relay (CR1),
through the Starter Contactor (SC) coil, and to the
Start/Stop Switch (SW1). However, the Switch contacts
are open and the circuit is incomplete.
4. Battery voltage is available through Fuse (F1), through
the Control Relay (CR2) actuating coil, and to the
Start/Stop Switch (SW1). However, the Switch contacts
are open and the circuit is incomplete.
5. Battery voltage is available to the Battery Charge Rec­
tifier (BCR), via Wire #13, 15 amp Fuse (FI), Wire #15,
and to a Battery Charge Rectifier (BCR). However, BCR
diode action inhibits Current flow.
Circuit Condition- Engine Cranking
B
When the Start/Stop Switch is held at its START posi­
tion, the following sequence of events occurs
1. Start/Stop Switch closure connects the Control Relay
(CR2) and the Starter Contactor (SC) actuating coils to
frame ground.
2. The Starter Contactor (SC) energizes and its contacts
close to deliver battery voltage to (a) Starter Motor (SM)
and (b) a Choke Solenoid (CS) and (c) a Choke Module
(CM). The following events then occur:
a. Starter Motor (SM) energizes and the engine
cranks.
b. Battery voltage is delivered to the Choke Module
(CM), via Wire 16, the Choke Solenoid coil, and Wire
90. Choke Module (CM) action opens and closes
this circuit to ground at a rate dependent on ambient
temperature, to energize and de-energize the Choke
. Solenoid. Choke Solenoid (CS) opens and closes
the carburetor choke.
c. Battery voltage delivered to the Choke Module
(CM) is delivered to the generator Rotor windings via
a Field Boost Resistor and Diode (housed in the
Choke Module), Wire 4 and the Rotor brushes and
slip rings. This is field boost.
LEGEND
-
" 1
>-
►-
7
^ &
■ t °
Ife
-gAAAn
&
BCRc
CB1 a
CB2a
CH -
CM c
CR1 -
CR2-
CS -
FI a
FP -
QT -
HM c
IMI -
IM2.
ISD.
LI
-
. LOP-
R1 -
. BATTERY CHARGE RECTIFIER
CIRCUIT BREAKER- 30 AMP
CIRCUIT BREAKER
. CHOKE HEATER
.CHOKE MODULE
I CONTROL RELAY
. CONTROL RELAY
. CHOKE SOLENOID
FUSE- 15 amp
FUEL PUMP
GROUND TERMINAL
. HOURMETER (Optional)
IGNITION MAGNETO
IGNITION MAGNETO
K3NmON SHUTDOWN
RUN LIGHT
. LOW OIL PRESSURE, SWITCH
RESISTOR-1 ohm, 25 watt
SC - STARTER CONTACTOR
SM - STARTER MOTOR
SW1 - START/STOP SWITCH
SPI - No. 1 SPARK PLUG
SP2 - No. 2 SPARK PLUG
TC o TERMINAL CONNECTOR
- WIRE NUT CONNECTION