Section 1.5 - Automatic Operating Parameters; Introduction; Utility Failure; Cranking - Generac Power Systems CorePower Repair Manual

Section 1.5
Automatic Operating Parameters

INTRODUCTION

When the generator is installed in conjunction with a transfer
switch, either manual or automatic operation is possible.

UTILITY FAILURE

Initial Conditions
The generator is in AUTO, ready to run, and the transfer switch
is running on Utility. When Utility fails (below 65% of nominal),
a 10 second line interrupt delay time is started. If the Utility is
still not present when the timer expires, the engine will crank
and start. Once started a five (5) second engine warm-up timer
will start.
When the warm-up timer expires the controller will transfer load
to the generator. If Utility voltage is restored (above 75% of
nominal) at any time between the initiation of the engine start
and when the generator is ready to accept load, (five 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 switch will remain in the "Utility" position.

CRANKING

The controller will cyclic crank the engine 5 times as follows:
16 second crank, 7 second rest, 16 second crank, 7 second
rest, followed by 3 additional cycles of 7 second crank followed
by 7 second rests.
Failure To Start
Failure to start is defined as any of the following occurrences
during cranking.
1. Not reaching starter dropout within the specified crank
cycle.
Note: Starter dropout is defined as 4 cycles at 1,000 RPM
2. Reaching starter dropout, but not reaching 2200 rpm
within 15 seconds. After which the controller will go into
a rest cycle of 7 seconds, the continue the rest of the
crank cycle.
Note: 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 the crank cycle
1. Starter motor will not engage within 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 star ter energizes, the controller will begin
looking for engine rotation. If it does not see an RPM
signal within 3 seconds it will shut down and latch out on
"RPM Sensor loss"
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5. Once the controller sees an RPM signal it will energize the
fuel solenoid and continue the crank sequence. The fuel
solenoid does not activate earlier because if the engine
does not crank, this would potentially fill the engine/
exhaust up with unspent fuel. It takes at least 3 seconds
to detect cranking on the engine with a magneto RPM
measurement. This would result in 3 seconds of fuel
being delivered, increasing the chances of a backfire.
6. The 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 the engine stops turning between starter dropout and
2200 RPM the controller will go into a rest cycle of 7
seconds and re-crank ( if additional crank cycles exist.)
9. Once star ted the generator will wait for a hold off
period before starting to monitor oil pressure and oil
temperature. Refer to Section 4.2 "Engine Protective
Devices"
10. During a MANUAL crank attempt, if the AUTO-OFF-
MANUAL switch is set from MANUAL to OFF, the crank
attempt will abort.
11. During automatic crank attempt, if the Utility returns, the
crank cycle does NOT abort, but continues until complete.
Once the engine starts, it will run for one minute then
shutdown.

LOAD TRANSFER PARAMETERS

The transfer of load when the generator is running is dependent
upon the operating mode as follows:
Manual
• No transfer to Standby when Utility is present
• Transfer to Standby will occur if Utility fails (below 65% of
nominal) for 10 consecutive seconds.
• Transfer back to Utility when Utility returns for 15 consecu-
tive seconds. The engine will continue to run until removed
from the Manual mode.
Auto
• Transfer to standby will occur if Utility fails below (65% of
nominal) for 10 consecutive seconds.
• A five second engine warm-up timer will initialize
• Transfer back to the "Utility" position if Utility subsequently
returns
• Transfer to the "Standby" position if Utility is still not pres-
ent.
• Transfer back to Utility once Utility returns (above 75% of
nominal) for 15 seconds.
• Transfer back to Utility, if present, if the generator is shut-
down for any reason ( such as the switch turned to the OFF
position or a shutdown alarm.
GENERAL INFORMATION