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 ELECTRIC PROTECTIVE SYSTEM
SYSTEMS OPERATION
ENGINE SHUTDOWN DUE TO FAULT:
LOW OIL PRESSURE
(AT ENGINE SPEEDS BELOW OIL STEP SPEED
SETTING)
As engine is started and begins to run, crank terminate switch ESS(CT)
opens across terminals ESS-11 and ESS-12 and closes across terminals
ESS-11 and ESS-10. This immediately arms the system when current is
sent to Control I (terminal 1) of time delay relay (TD1), which closes TD1
relay contacts (line 25) across terminals TD1-6 and TDI-7.
At the same time that TD1 is armed, there is current flow to Control 2
(terminal 2) of time delay relay (TD2) if oil pressure switch (OPS I ) has not
yet opened. The engine oil pressure has 9 seconds (from the time that
TD1 is armed) to increase to the 140 kPa (20 psi) necessary to open
OPS1. If OPSI does not open, TD2 contacts will close across terminals
TD2-6 and TD2-7 and slave relay (SRI) will be energized. SR1 relay
contacts (line 42) will now open across terminals SRI-I and SRI-2, and SRI
relay contacts (line 40) will close across terminals SR1-1 and SR 1-3. The
fuel shut-off solenoid (FSOS) is now energized, and will shut the fuel off to
the engine.
If the engine had been running (with no faults) at a speed less than the
oil step setting, and then lost engine oil pressure, the protection system
would cause engine shutdown in the same way as shown in Fig. 7. OPS1
would close when oil pressure decreased to 105 kPa (15 psi), and 9
seconds later the engine would shut down.
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