Auto Exercise Time; Fine Voltage Adjustment; Shutting Down The Unit - Generac Power Systems MAGNUM MLT4250 Owner's Manual

Operation

Auto Exercise Time

Units installed in a standby application should be
exercised regularly to maintain operating condition and to
ensure responsiveness in an emergency situation. The
following procedure demonstrates how to run (exercise)
the unit on a time schedule:
1. Press PAGE SELECT until "Password" appears at
the top of the screen.
2. Press  until "Date/Time" is selected and press
ENTER.
3. Press  until "Timer1 Repeat" is selected and
press ENTER.
4. Choose the day or days the unit should run and
press ENTER.
5. Press  until "Timer1 ON Time" is selected and
press ENTER.
6. Adjust the desired time to start running and press
ENTER.
7. Press  button until "Timer1Duration" is selected
and press ENTER.
8. Adjust the time period to the length of time the unit
should run after starting and press ENTER.
9. Press PAGE SELECT three times to return to the
main menu.
10. Press the AUTO button to switch modes to
automatic.
NOTE: The controller must be in AUTO mode to run at
the programmed time. Use a trickle battery charger or
solargizer to prevent the controller from draining the
battery while in AUTO mode.

Fine Voltage Adjustment

Upon startup of the unit, the Running screen will display
V Detect and will countdown from 45 seconds to zero.
This is a safety feature of the controller to protect the
generator from over or under voltage upon startup.
V Detect is a 45 second time delay and countdown
process before the MDC records the generator nominal
output voltage. This nominal generator voltage is then
compared to the current set point voltage of the voltage
selector switch. If the nominal voltage recorded by the
controller is greater than or lower than the current set
point voltage of the voltage selector switch setting by
10% or more, the controller will shut the unit down
automatically. The display will read: "Wrn Gen L1 <V",
"Wrn Gen L2 <V", "Wrn Gen L3 <V" or "Sd Gen L1 <V",
"Sd Gen L2 <V", "Sd Gen L3 <V". This means the
controller warned ("WRN") or shutdown ("SD") the unit
due to an output voltage irregularity.
The output voltage of the generator may be adjusted
after the unit is running by using the fine voltage
adjustment screw (A). The adjusting screw is located
directly below the Control Power switch on the control
26
panel. This screw turns a rheostat that will provide an
increase (+) or a decrease (-) in the generator output
voltage as displayed on the generator display screen on
the MDC. If the voltage is increased or decreased too
fast or too slow, the unit will automatically shut down.
This adjustment needs to be made within the 45 second
delay and countdown to zero period.
CONTROL
CONTROL
Figure 3-22. Fine Voltage Adjustment Screw
To adjust the output voltage, check the output voltage on
the Liquid Crystal Display (LCD) window labeled Gen
freq & Hz. Look at the "L1N" voltage or the "L12" voltage
on the display. The generator nominal output voltage
should be within 10% of the voltage rating on the voltage
selector switch.
To adjust the output voltage, use a flat head screwdriver
to turn the screw in the desired direction until the required
voltage shown on the LCD window matches the stated
voltage on the voltage selector switch.
For Example: With the voltage selector switch set to 208/
120V 3 phase position, the voltage displayed on the
screen must be within ± 10% of the 208/120 position
(188-228V Line to Line/108-132V Line to Neutral).
NOTE: Each time the voltage selector switch is changed
from one setting to another, an adjustment will need to be
made using the fine voltage adjustment screw.

Shutting Down the Unit

Check with personnel using power supplied by the unit
and let them know the power is going to be turned off.
Make sure the power shutdown will not create any
hazards by accidentally turning off equipment that needs
to remain running (pumps, compressors, lights, etc.).
1. Remove all loads from the outlets.
2. See Figure 3-23. Switch the individual circuit
breakers for each light OFF (O) (A).
Owner's Manual for MLT Light Tower
ON
A
OFF
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