TM 55-1930-209-14&P-9-1
2-12.
Generator set alarm and shutoff systems The SSG’s and SAG have built-in alarm and shutoff systems. Alarms
and emergency shutoff systems, discussed in this section, function whether SSG’s are operated at the engine or at the
switchboard.
2-12.1
Alarm systems Three alarm switches are set at levels of coolant temperature, oil pressure, and rotations per minute
(rpm) less critical than the emergency shutoff controls described in paragraph 2-12.2. When alarm conditions exist, three
red lights in a row of four ENGINE FAILURE lights (Figure 2-11) on affected generator set switchboard panel, light up. When
EMS is on (TM 55 930-209-14&P-1 1), these critical conditions are also made known to the crew by a blinking display on the
EMS video monitor on the forward ROWPU bulkhead, by a strobe light and horn in the ROWPU space, a horn on the
deckhouse top, and a buzzer in the day room. Alarms warn operators that an unsafe condition is developing and that
corrective action must be taken immediately. If action is not taken, an emergency shutoff solenoid will shut down the SSG.
Alarms continue until turned off or until the unsafe condition is corrected. When the unsafe condition is corrected, switches
automatically reset The fourth alarm condition, reverse power, is discussed in paragraph 2-14.
2-12.2
Shutoff systems. During operation, four electrically-operated shutoff systems function in the following manner.
When a critical condition exists, a switch automatically doses the circuit to a shutoff solenoid. This action stops fuel flow to
the cylinders and shuts off the engine. The shutoff control either resets itself or must be reset by a crew member before the
engine restarts. These shutoff systems are discussed below.
CAUTION
Sensing element must be submerged In coolant to operate. If coolant Is low, engine can
overheat and automatic shutoff will not function to prevent damage to engine.
a.
High water temperature shutoff switch is located in the water temperature regulator housing. When the water
temperature is too high, the solenoid fuel cutoff switch closes and the engine shuts off. When the engine stops,
switch the ECS or ENGINE START/STOP switch to STOP. This will prevent the temperature shutoff switch
from automatically restarting the engine when this switch resets after the coolant cools. Troubleshoot the
cooling system and repair as necessary. Restart the engine by following the procedures in paragraphs 2-11
and 2-13.
b.
Low oil pressure shutoff switch is on the side of engine with oil lines connecting to the switch. When engine oil
pressure is too low, the solenoid fuel cutoff switch doses and shuts off the engine. When engine stops, switch
the ECS or ENGINE START/STOP switch to STOR Troubleshoot lubricating system and repair as necessary.
Before restarting engine, reset oil pressure shutoff switch by pushing reset button until it latches. After engine
starts and develops oil pressure, pressure will push reset button to extended position. If button remains in reset
position, engine is not developing normal oil pressure. Troubleshoot and correct as necessary. Restart engine
by following procedures in paragraphs 2-11 and 2-13.
CAUTION
If the oil pressure shutoff switch reset button does not move to extended position after
engine Is running, the shutoff switch Is not protecting the engine from low oil pressure.
c.
Electronic overspeed shutoff switch protects the engine as follows:
CAUTION
Sudden stopping of engine under load may be hazardous to operations being powered by an online
generator self engine overspeeds, however, f must be stopped immediately as a runaway engine will
destroy Itself.
2-24
