Section 3 — Operation
Air-cooled Generators
SEQUENCE OF AUTOMATIC
OPERATION
Initial Conditions: Generator in Auto, ready to run, load being supplied by utility source. When utility fails (below 65% of nominal), a 10 second line interrupt delay time is started. If the utility is still gone when the timer expires, the engine will crank and start. Once started, a five (5) second engine warm-up timer will be initiated.
When the warm-up timer expires, the control will transfer the load to the generator. If the utility power is restored (above 75% of nominal) at any time from the initiation of the engine start until the generator is ready to accept load (5 second warm-up time has not elapsed), the controller will complete the start cycle and run the generator through its normal cool down cycle; however, the load will remain on the utility source.
3.3.2 CRANKING
The system will control the cyclic cranking as follows: 16 second crank, seven (7) second rest, 16 second crank, seven (7) second rest followed by three (3) additional cycles of seven (7) second cranks followed by seven (7) second rests.
Choke Operation
1. The 990 engines have an electric choke in the air box that is automatically controlled by the electronic control board.
Failure to Start
This is defined as any of the following occurrences during cranking.
1. Not reaching starter dropout within the specified crank cycle.
Starter dropout is defined as four (4) cycles at 1,000 RPM.
2. Reaching starter dropout, but then not reaching 2200 RPM within 15 seconds. In this case the control board will go into a rest cycle for seven (7) seconds, then continue the rest of the crank cycle.
During a rest cycle the start and fuel outputs are de-energized and the magneto output is shorted to ground.
Cranking Conditions
The following notes apply during cranking cycle.
1. Starter motor will not engage within five (5) seconds of the engine shutting down.
2. The fuel output will not be energized with the starter.
3. The starter and magneto outputs will be energized together.
4. Once the starter is energized the control board will begin looking for engine rotation. If it does not see an RPM signal within three (3) seconds it will shut down and latch out on RPM sensor loss.
5. Once the control board sees an RPM signal it will energize the fuel solenoid, drive the throttle open and continue the crank sequence.
6. Starter motor will disengage when speed reaches starter dropout.
7. If the generator does not reach 2200 RPM within 15 seconds, re-crank cycle will occur.
8. If engine stops turning between starter dropout and 2200
RPM, the board will go into a rest cycle for seven (7) seconds then re-crank (if additional crank cycles exist).
9. Once started, the generator will wait for a hold-off period before starting to monitor oil pressure and oil temperature
(refer to the Alarm Messages section for hold-off times).
10. During Manual start cranking, if the Mode switch is moved from the Manual position, the cranking stops immediately.
11. During Auto mode cranking, if the Utility returns, the cranking cycle does NOT abort but continues until complete. Once the engine starts, it will run for one (1) minute, then shut down.
The transfer of load when the generator is running is dependent upon the operating mode as follows:
1. Manual
•
•
Will not transfer to generator if utility is present.
Will transfer to generator if utility fails (below 65% of nominal for 10 consecutive seconds.
• Will transfer back when utility returns for 15 consecutive seconds. The engine will continue to run until removed from the Manual mode.
2. Auto
• Will start and run if Utility fails for 10 consecutive seconds.
•
•
Will start a five (5) second engine warm-up timer.
Will not transfer if utility subsequently returns.
• Will transfer to generator if utility is still not present.
• Will transfer back to utility once utility returns (above 75% of nominal) for 15 seconds.
•
•
Will transfer back to utility if the generator is shut down for any reason (such as the switch is in the OFF position or a shutdown alarm.
After transfer, will shut down engine after one (1) minute cool-down time.
3. Exercise
•
•
Will not exercise if generator is already running in either Auto or Manual mode.
During exercise, the controller will only transfer if utility fails during exercise for 10 seconds, and will switch to Auto mode.
Initial Condition: Generator supplying power to customer load.
When the utility returns (above 75% of nominal), a 15 second return to utility timer will start. At the completion of this timer, if the utility supply is still present and acceptable, the control will transfer the load back to the utility and run the engine through a one (1) minute cool down period and then shut down. If utility fails for three (3) seconds during this cool down period, the control will transfer load back to the generator and continue to run while monitoring for utility to return.
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