Engine Protective Devices - Generac Power Systems 004721-0, 004722-0, 004723-0, 004724-0, 004725-0, 004725-1, 004725-2, 004725-3, 004726-0 Owner's Manual

Model Rating
004721/004722 15,000
004723/004724 20,000
004725/004726 25,000
Recommended fuels should have a Btu content of at
least 1,000 Btus per cubic foot for natural gas and at
least 2,520 Btus per cubic foot for LP gas. Ask the
fuel supplier for the Btu content of the fuel being
used.
Fuel pressure for a natural gas set up should be five
inches to 14 inches of water column (0.18 to 0.5
psi) at all load ranges.
Fuel pressure for an LP vapor set up should be 11
inches to 14 inches of water column (0.4 to 0.5
psi) at all load ranges.
A seperate gas line and regulator may be needed
to assure proper gas pressure to the generator.
Improper gas pressure can cause hard starting and
affect engine durability.
Gaseous fuels such as natural and LP
!
(propane) gas are highly explosive. Even the
slightest spark can ignite such fuels and cause
an explosion. No leakage of fuel is permitted.
Natural gas, which is lighter than air, tends to
collect in high areas. LP gas is heavier than air
and tends to settle in low areas.
1.7

ENGINE PROTECTIVE DEVICES

The engine has several safety switches which cause
the engine to automatically shut down under the fol-
lowing conditions: low oil pressure, high coolant tem-
perature, engine overspeed, low coolant level or over-
crank (Figure 1.3).
Figure 1.3 - Engine Protective Devices
Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators
Figure 1.2 - Main Circuit Breaker
Phase Actual Current
1
1
1
* Amp Rating of CB structured under model.
NOTE:
Section 1 - General Information
C/B Rating*
62.5 70
83.3 90
104.2 125
1.7.1
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 1.4).
Figure 1.4 - Low Oil Pressure Switch
1.7.2 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 1.5).
Figure 1.5- High Coolant Temperature Switch
1.7.3
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 1.6 on page 6).
% over rating
112%
108%
120%
LOW OIL PRESSURE SWITCH
LOW COOLANT LEVEL SWITCH
Generac ® Power Systems, Inc.
Circuit Breaker
70A BQ2
90A BQ2
125A BQ2
5