D346 MARINE ENGINE Caterpillar

Single Unit Operation


Initial Start-Up

1. Remove the left side access panel of the generator.
2. Loosen the locknuts on the voltage droop, voltage level, and voltage gain controls.
3. Turn the voltage droop control (1) counterclockwise to zero droop and tighten the locknut.

1. Voltage Droop 2. Voltage Level 3. Voltage Gain 4. Circuit Breaker (SR4 Generator Only).

4. Turn the gain control (3) counterclockwise to zero, then turn the gain control to about 1/4 of full range of clockwise travel.
5. Perform required maintenance on engine before starting.
6. Start the engine and allow it to warm.
7. Increase engine speed to full governed speed (high idle).
8. Observe the voltmeter reading. If desired voltage is not indicated, set no load voltage with voltage level control (2).
9. Close the load circuit breaker and apply full load gradually. Adjust governor control until nameplate frequency is on the Hertz meter.
10. a. If voltmeter reading increases with full load applied, turn gain control (3) slightly in counterclockwise direction.
b. If voltmeter reading decreases with full load applied, turn gain control (3) slightly in clockwise direction.
11. Remove load, adjust voltage level control (2) if necessary to obtain desired voltage.
12. Apply the load, observe voltmeter reading. Repeat steps 9 thru 12 until no load voltage equals full load voltage.
13. Tighten the locknuts on all controls and install the access panel of the generator.
14. Circuit breaker (4) will open if excessive field current should occur. Push to reset the circuit breaker. If breaker opens again, contact your Caterpillar dealer.


1. Make all preliminary engine starting checks.
2. Be sure the main or line circuit breaker is open.
3. Start the engine and allow it to warm up.
4. Adjust to full load RPM.
5. Close the main circuit breaker.
6. Apply the load. Do not try to apply full load in one move, rather apply the load in increments to maintain system frequency at a constant level.
7. Readjust governor for rated frequency.


1. Remove the load in increments.
2. Open the circuit breaker.
3. Allow the engine to run for 5 minutes to cool.
4. Stop the engine.
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