1.12.1 LOW OIL PRESSURE SWITCH
This switch is normally-closed (N.C.) but is held open
by engine oil pressure during engine running. Should
operating oil pressure drop below about 8-10 psi
(55-68 kPa), the switch contacts close and the engine
shuts down automatically (Figure 1.6).
Figure 1.6 - Low Oil Pressure Switch
1.12.2 HIGH COOLANT TEMPERATURE
SWITCH
This normally open (N.O.) thermostatic switch has
sensing tip which is immersed in captive coolant.
Should coolant temperature exceed about 230°F
(110°C), the switch contacts close, which causes the
engine to shut down automatically (Figure 1.7).
Figure 1.7 - High Coolant Temperature Switch
1.12.3 LOW COOLANT LEVEL SWITCH
Should engine coolant level drop below the level of
the high coolant temperature switch, it is possible for
the engine to overheat without automatic shutdown.
To prevent such overheating without automatic shut
down, the engine has a low coolant level sensor. If the
engine coolant drops too low, the engine automatical-
ly shuts down (Figure 1.8).
Figure 1.8 - Low Coolant Level Sensor
1.12.4 OVERSPEED SHUTDOWN
The circuit board on liquid cooled units receives AC
frequency (rpm) signals directly from the stator AC
power windings, via sensing leads S15 and S16.
Should AC frequency exceed about 72 Hertz, circuit
board action will automatically shutdown the engine
(Figure 1.9).
*Rated power of generator is subject to and limit-
ed by such factors as ambient temperature, alti-
tude, engine condition, and other factors. Engine
power will decrease about 3.5% for each 1000 feet
above sea level and will decrease an additional 1%
for each 10°F above 60°F. Maximum output power
of the generator is limited by maximum engine
power.
Figure 1.9 - Control Circuit Board
1.12.5 PCB OPERATION LED’S
• LED 1 is RED. This LED will be on when UTILITY
sensing is NOT available to the circuit board. This
LED will function only when the AUTO/OFF/
MANUAL switch is set in the AUTO position.
• LED 2 is YELLOW. This LED will be on when the
circuit board battery charger is on. This LED will
cycle on and off with the battery charger, 4.85
hours on then 4.85 hours off.
• LED 3 is GREEN. This LED will flash when the cir-
cuit board has LOAD voltage available to it. This
LED will function when voltage is available across
T1 and T2.
A
E
17
1
2002 GENERAC POWER SYSTEMS, ASSY #076009A
CUT R83
FOR 50HZ
PRE-PACKAGED STANDBY
U1
U12
U2
U14
U13
U3
U5
U8
U15
U10
U16
U17
U9
U4
U7
C
R2
C
R
3
C
R1
2
C
R1
3
C
R1
4
C
R1
5
CR16
C
R2
0
C
R2
1
C
R2
4
C
R3
0
C
R3
2
C
R3
6
C
R2
9
CR1
CR7
C
R1
7
C
R3
3
C
R3
4
C
R3
5
C
R1
8
C
R
8
C
R1
9
C23
C24
C1
C3
C19
C20
C21
C13
C2
R12
R
66
R
16
R
81
R1
R2
R3
R4
R5
R6
R7
R
8
R9
R10
R11
R
13
R
17
R
18
R
22
R
23
R
24
R
25
R
26
R
27
R
29
R
30
R
31
R
32
R
33
R
35
R
36
R
37
R
38
R
39
R
40
R
41
R
42
R
43
R
44
R
46
R
47
R
50
R
51
R
52
R
53
R56
R
57
R
59
R60
R
61
R
62
R
63
R
65
R
67
R68
R
69
R
70
R
71
R
72
R
74
R
75
R
76
R77R
R
78
K1
K2
SW1
R
14
R
20
R
15
R
21
R
19
CR37
J2
M
M2
M3
M4
M5
M1
M1
Q13
U6
Q7
K3
C
R3
8
C
R4
0
C25
K4
R
82
R55
Q9
Q1
Q3
Q5
Q4
Q6
Q11
Q12
Q2
M8
M1
M1
M M
M1
M1
M1
M1
C5
C
C4
C8
CR41
U18
U19
R
83
U20
C14
C15
C16
C7
C10
C9
C11
C 1
C17
C18
C12
C22
BR1
J1
M9
M10
R
54
M14
M15
LED1
LED2
LED3
Q14
Q16
R
48
R
84
R
85
R
86
R
87
R
88
Q15
Section 1 — General Information
Generac Liquid-cooled 20 kW Generator
Generac
®
Power Systems, Inc.
7
