Generac Power Systems NP-40G - Manual (Page 12)

Section 1.2- MAJOR GENERATOR COMPONENTS
Rotor Hub
See Figure 2. The Rotor Hub Is balanced with the
Rotor and must be replaced with the Rotor as an
assembly. Part of the engine ignition system is
pressed onto the Hub and can be replaced only as
part of the Rotor and Hub assembly.
Stator Retaining Ring
The Stator Retaining Ring is made of dIe-cast
aluminum. Four hex head capscrews with
lockwashers pass through holes in the Retaining
Ring, to retain the Stator Assembly to the Stator
Adapter (Item 7, Figure 1).
Stator Assembly
The 2-phase Stator is made up of eight (8) wind­
ings, with leads brought out as shown in figure 3.
Figure 4 is a schematic representation of each sta­
tor winding. Note that there are four (4) power
phase windings (Leads AC2, AC1, SI2, SI1 and 11);
a timing winding (Leads TIM1 and TIM2); a power
supply winding (Leads PS1, PS2); and a dual bat­
tery charge winding (Leads 55, 66, 77).
The Stator produces a frequency of 336 to 540
Hertz, which corresponds to engine speeds
between 2520 and 4050 rpm. This means the gen­
erated frequency is between six and nine times
the desired frequency of about 60 Hertz.
Stator Adapter
The Adapter Is retained to the engine by means
of four hex head capscrews. The Stator Is retained
to the Stator Adapter and Is “sandwiched'' between
the Adapter and the Stator Retaining Ring.
Lower Fan & Flywheel
The Lower Fan and Flywheel are retained to the
engine PTO shaft by means of a conical washer and
an Ml 6-1.50 hex nut. When assembling, tighten the
flywheel nut to 75 foot-pounds.
Engine
The engine is a single cyclinder, overhead valve
type manufactured by Generac Corporation. De­
pending on the specific generator Model Number,
either a GN-190 or a GN-220 engine is used on
NP-30 and NP-40 RV generators.
Stepper Motor
The Stepper Motor (Figure 5, next page) consists
of a stepper motor along with a gear and cam
arrangement which allows motor movement to
change the engine carburetor throttle setting. The
Motor Is controlled by output signals from the Com­
puter Control Circuit Board, which calculates the
number of steps the stepper needs to take and
generates the required signals to the Motor. The
circuit board signals the Motor to actuate in re­
sponse to changes In AC output voltage. Thus, In
response to decreasing AC output voltages, the
Motor will increase the throttle setting and engine
speed will Increase. Conversely, Increasing AC
output voltages will cause the Motor to decrease
throttle setting and engine speed will decrease.
Figure 3. Stator Pictorial View
-55 (BLACK)--------»<§)
-66 (BROWN)-
—77 (BROWN) T1M1 (ORANGE)
PS2 (YELLOW)
—TM2 (GRAY)
H T1M1 (
-PS1 (BROWN)-
■11 (BLUE) ---------
-AC2 (YELLOW)
-AC1 (GRAY)—
-SL1 (ORANGE)—
----- SL2 (BROWN)-------------
Figure 4. Schematic- Stator Windings
POWER
PHASE 1
AC1 a C2 AC2
b
POWER
PHASE 2
I ! I
I (7»CT«r|
II è
SL2
è
POWER I TIMING
SUPPLY I I
PS1 PS2
C «r ® ®
BATTERY
CHARGE
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