1
−
12
T-343
1.8 SAFETY DEVICES
Safety devices, such as circuit breakers, fuses, and
safety switches, protect system components from
damage.
The
AC generator, solid state battery charger, fuel
heater, high water temperature, safety relay, total time
meter and intake heater are protected by circuit
breakers. If a safety device opens and there is an
interruption of electrical current, the electronic governor
module will be de
−
energized, which will also
de
−
energize the fuel solenoid, interrupt the fuel flow to
the engine and stop the engine.
In units with auto restart, the engine, engine control
devices, and engine monitoring devices are protected
by the auto restart module, low coolant sensor (if
equipped), circuit breaker, low oil pressure switch, and
high water temperature switch. These safety devices
monitor system operating conditions and open a set of
electrical contacts when an unsafe condition occurs. If a
safety device opens and there is an interruption of
electrical current, the electronic governor module will be
de
−
energized, which will also de
−
energize the fuel
solenoid, interrupt the fuel flow to the engine and stop
the engine.
De
−
energizing the fuel solenoid shuts off the fuel supply
to the engine; thus stopping the engine. Safety device
specifications are provided in Table 1-4.
Table 1-4 Safety Devices
Unsafe Condition
Safety Switch
Switch Setting
ENGINE
Low engine lubricating oil pressure
Low oil pressure switch (LOP)
−
Automatic reset
Opens below 18 psig
(1.27 kg/cm
2
)
High engine cooling water temperature
Water temperature switch (HWT)
−
Automatic reset
Opens at 230
°
F (110
°
C)
Low coolant
Low coolant sensor
Automatic reset
Opens with a loss of 32
ounces of coolant
Excessive current draw by the safety re-
lay, fuel heater, water temperature gauge,
oil pressure gauge or total time meter
Circuit breaker (CB
−
2)
−
Automatic reset
Trips at 30 amps
Excessive current draw by the electronic
governor module
Fuse 1, 2, 3
Trips at 10 amps
INTAKE HEATER
Excessive current draw on intake heater
circuit
Circuit breaker (CB
−
3)
−
Automatic reset
Opens at 50 amps
BATTERY CHARGER
Excessive current draw on 230 volt feed
circuit
Circuit breaker (CB
−
5)
−
Manual reset
Opens at 3 amps
GENERATOR
Excessive current draw by load
Circuit breaker (CB
−
1, 460 volt)
−
Manual reset
Trips at 26 amps
(460 VAC)
