Sequence Of Automatic Operation; Crank Cycles And Overcrank Shutdown; Auto Start; Manual Start - Generac Power Systems Stationary emergency generator Owner's Manual

SEQUENCE OF AUTOMATIC OPERATION

Initial Conditions: Generator in Auto ready to run, load being sup-
plied by the Utility Source through the transfer switch.
1. When the utility voltage fails (falls below 60% of nominal), a
10-30 second (programmable) "line interrupt" delay timer is
started. The factory set time delay is 10 seconds. If at the
end of the line interrupt time the utility voltage is above 60%
the engine will not crank. If the utility voltage is still below
the 60% of nominal at the end of the line interrupt time, the
unit will crank and start. If the unit cranks for more than 10
seconds and the utility voltage rises above 80% of nominal
(programmed pickup voltage) and the unit has not started, the
crank cycle will abort.
2. As soon as the unit starts a 5 second "warm-up" timer is initi-
ated. When the warm-up timer expires the control will transfer
the load to the generator (through the RTS switch) if the utility
voltage is less than 80% of nominal. If the utility voltage is
greater than the 80% of nominal at the end of the warm-up
time the load will not be transferred to the generator and a one
minute low-speed cool down period will start. At the end of
the one minute cool down period the generator will stop.
3. Once the unit is running and the switch has transferred the
load to the generator the unit will monitor utility voltage.
When utility voltage returns (above the programmable pickup
voltage, normally 80% of nominal), a 15 second "Return to
Utility" timer will start. At the end of the return to utility time,
if the utility voltage is still above the pickup voltage, the unit
will transfer the load back to the utility source and run the unit
through a one minute cool down period. When the cool down
period is over the unit will shut down and be ready for the next
outage.
4. If during the cool down period utility voltage should fall below
60% of nominal the 5 second warm-up timer is initiated and
the unit will transfer the load back to the generator and con-
tinue to monitor the utility.

CRANK CYCLES AND OVERCRANK SHUTDOWN

If the unit fails to start during a cranking period it will display the
Overcrank Shutdown Alarm. The system will control the cranking
cycles as follows:
The first crank cycle is a 16 second crank time followed by a 7
second rest. The next 5 cycles will be 7 seconds of cranking time
each followed by a 7 second rest time.
If the unit fails to start by the end of the 6 crank/rest cycles
the Overcrank Shutdown Alarm will display and the unit will not
attempt to crank until the alarm is reset.

AUTO START

This unit is designed to automatically start in the event of a util-
ity failure or brown out condition. Brown out is defined as utility
voltage less than 60% nominal, while utility is considered good
when it is restored to at least the pickup value, 80% of nominal.
These levels are fixed. The "Line Interrupt period" is an adjustable
parameter by the dealer. If 2-wire start mode is activated, the unit
will start when 2-wire start is active.
12/11 E Rev. CntrlNexus001
Control Panel

MANUAL START

Allows the user to start and run the generator manually.
Transfer of the load to the generator will occur if utility is lost while
the unit is running in the manual mode (only if activated).

ALARM AND WARNING MESSAGES

Alarms are defined as "Latching" which means they must be
cleared before the alarm message on the screen will clear. They
can be of type "Shutdown" or not and are logged in the alarm log.
Alarms are all annunciated on the display).
Warnings are "Non Latching" meaning the message automati-
cally clears when the warning condition goes away. Warnings can
not be of type "Shutdown" but they are logged in the alarm log.
Warnings are all annunciated on the display.

LOW OIL PRESSURE SHUTDOWN ALARM

There is a 10 second delay before oil pressure is monitored.

HIGH COOLANT TEMPERATURE SHUTDOWN ALARM

There is a 10 second delay before engine temperature is moni-
tored.
Once running there is a 1/4 second delay before shut down. The
limit is set at 125° C or 257° F.

OVERCRANK SHUTDOWN ALARM

Occurs if the engine has not started within the specified crank
cycle.

OVERSPEED SHUTDOWN ALARM

Warning indicator is measured and calculated by the microproces-
sor. Overspeed is defined as +20% of nominal engine speed for 3
seconds, or +25% immediate.
Nominal engine speed = 60.0 Hz

RPM SENSOR FAILURE SHUTDOWN ALARM

During cranking: If the board does not see a valid RPM signal
within four (4) seconds of cranking it will shut down and lock out
on RPM sensor loss.
During running: If the RPM signal is lost for one full second the
board will shut the engine down, wait 15 seconds, then re-crank
the engine if in AUTO, it will not re-crank in MANUAL.
If no RPM signal is detected within the first four (4) seconds of
cranking, the control board will shut the engine down and latch out
on RPM sensor loss.
If the RPM signal is detected the engine will start and run normally.
If the RPM signal is subsequently lost the control board will try
two more re-cranks before latching out and flashing the RPM
Sensor Failure message (if it is in AUTO).
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