Under-Frequency; Clearing An Alarm - Generac Power Systems 7 kW NG Repair Manual

ENGINE/DC CONTROL
3. The 410cc engines have a choke behind 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
1,500 RPM (1,800 RPM for 8kW units).
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.
3. During a rest cycle the star t and fuel outputs are
de-energized and the magneto output is shor ted to
ground.
Cranking Conditions
The following notes apply during the 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 star ter 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 cranking, if the AUTO-OFF-MANUAL switch is
switched to the OFF position, cranking stops immediately.
11. During Auto mode cranking, if the Utility returns, the
cranking cycle does NOT abor t but continues until
complete. Once the engine starts, it will run for one (1)
minute, and then shut down.
PART 4

UNDER-FREQUENCY

After starting, if the generator stays under a set frequency for
more than 30 seconds, it will shutdown.
Table 21. Under-frequency Shutdown Settings
Unit Hertz
50 Hz
60 Hz with 0H6680A Controller
60 Hz with 0H6680B Controller

CLEARING AN ALARM

When the generator is shut down due to a latching alarm, the
AUTO-OFF-MANUAL switch must be set to the OFF position and
the "Enter" key pressed to unlatch any active fault and clear the
corresponding fault alarm message.
Section 4.2
Engine Protective Devices
Shutdown Frequency
40 Hz
50 Hz
55 Hz
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