ARMY TM 9-6115-604-12NAVY NAVFAC P-8-633-12(6)Speed switch SS1/SS2/SS3 is connected to the tachometer drive on the engine fuel pump and sensesengine speed at all times. When engine speed rises above 600 rpm, SS1 trips to simultaneously connectbattery positive to M7 pin A and disconnect battery positive from M7 pin 4. Loss of battery positive at K7pin 4 results in loss of power at M7 pin 7, crank relay K3 deenergizes and starter motors B1 and B2 are cutoff as described in step (5), above. The engine will rapidly continue to accelerate under its own power.(7)SS2 will close when engine speed reaches 1200 rpm. Thereafter, shutdown relay K14 is self-latching ifEMERGENCY SHUTDOWN pushbutton S7 is pressed or MASTER SWITCH S9 is set to STOP whileengine speed is above 1200 rpm. When the relay is energized, the normally closed contacts of relay K14open to cut off battery positive from the DC control circuits. Crank timer relay M7 Is Inhibited, preventingthe operator from attempting to restart the engine while it is freewheeling at 1200 rpm or higher. Theoperator should wait until the engine comes to a complete halt before restarting.(8)Engine speed stabilizes at 1500 rpm (50 hertz operation) or 1800 rpm (60 hertz operation) Engine speed iscontrolled thereafter by load sharing module A104.(9)15 to 25 seconds after the appearance of battery positive at M7 pin A (refer to step (6), above), batterypositive appears at M7 pin B to energize relays K17A and self-latching relay K17B. Normally opencontacts of K17A close to arm oil pressure shutdown relay K18. A second set of normally open K17Acontacts close to arm undervoltage annunciator fault relay A10K8, low oil pressure annunciator fault relayA10K2, and underfrequency annunciator fault relay. All K5 Battery positive remains available at K7 pin Bfor about 40 seconds, then switches off with no effect upon the circuitry.(10)The engine will continue to run at operating speed until manually shut down (refer to step f, below) orautomatically shut down by a protective circuit (refer to step d, below). Control of of the engine atoperating speeds is accomplished via the AC power generation and electrical control circuits. Refer toparagraph 4-32 for details.d.GeneratorSetProtectiveCircuits.There are nine fault sensors used to monitor conditions in the engine, coolingsystem, lubricating system, and fuel system. They are the fuel level switches FL3 and FL4; oil pressure alarmswitch OP2, and oil pressure shutdown switch OP1, high oil temperature switch OT2, overspeed switch SS3,coolant level switches S13 and S14; coolant temperature warning switch WT2, and coolant temperatureshutdown switch WT1. On a fault condition, these sensors cause a warning to be displayed to the operator.Additionally, some of them cause a generator set shutdown. These sensors function In the DC control circuit asfollows:(1)Low Fuel Level Switch FL3. Low fuel level switch FL3 is mounted through the top of the generator set fueltank and is accessible through the floor of the control room. FL3 will close on a low fuel condition to energize self-latching relay A10K5 in the annunciator alarm system. Annunciator horn LS1 sounds and annunciator panel light A9DS5flashes while the generator set continues to run. A10K5 also energizes low fuel level time delay relay K23. After apreset time delay (normally 35 minutes) relay K23 will energize fault shutdown relays K20A and K20B. Relay K20Adeenergizes self-latching engine run relay K15B. As a result, engine fuel solenoid L1 loses power, closes, and cuts offfuel to the engine; the engine shuts down. Relay K20B energizes circuit breaker trip relay K30. Relay K30 energizes thetrip coil n load circuit breaker CB101, opening the breaker to disconnect generator G1 from the bus. The generator setcannot be restarted until the annunciator alarm system is reset via ANNUNCIATOR RESET pushbutton S12 on the upperdoor of cabinet A. Theoretically, low fuel level fault shutdown will not occur because the operator will replenish thegenerator set fuel supply and reset the alarm circuit before the time delay (normally 35 minutes) elapses. Note that If theoperator replenishes the fuel supply, but fails to reset the alarm circuit via ANNUNCIATOR RESET pushbutton S12, lowfuel level time delay relay K23 will still time out and cause a generator set shutdown. The operator will not be able toreset the alarm circuit before replenishing the fuel, but failure to reset the circuit after refueling will result in a shutdown.The purpose of this circuit is to back up the fuel transfer system circuit. If the fuel transfer system circuit is operationaland set to AUTO, low fuel level alarm relay A10K5 will not trip. If the generator set is connected to an adequate externalfuel supply.4-68
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
