ELECTRIC PROTECTIVE SYSTEM
ENGINE SHUTDOWN DUE TO FAULT:
When engine speed increases above the overspeed setting ( 118% of
rated speed) of the electronic speed switch (ESS), the overspeed switch
ESS(OSS) will close across terminals ESS-7 and ESS-8 (line 23). This
completes the circuit from the battery through overspeed indicator (OSI)
and also through both slave relays (SRI and SR2) as shown in Fig. 9.
Both slave relays (SR1 and SR2) are now energized at the same time.
SR2 contacts will close across terminals SR2-1 and SR2-3 to activate air
shut-off solenoid (ASOS). ASOS will now shut the inlet air off to the
engine. At the same time, SRI contacts open across terminals SRI-I and
SRI-2 (Line 42) and close across terminals SRI-I and SR1-3 (line 40).
The fuel shut-off solenoid (FSOS) is now activated, and will shut the fuel
off to the engine.
A reset button on the ESS must be pushed to open the overspeed
switch ESS(OSS), and the air shut-off lever (at top of air inlet housing)
must be manually reset before the engine will run.