- Guardian Liquid-Cooled, Prepackaged Standby Generator Owner's Manual

3.2.2 “OFF” POSITION
This switch position shuts down the engine. This posi-
tion also prevents operation.
3.2.3 “MANUAL” POSITION
Set the switch to Manual to crank and start the engine.
Transfer to standby power will not automatically occur
unless there is a utility failure.
With the switch set to AUTO, the engine may
crank and start at any time without warning.
Such automatic starting normally occurs when
utility power source voltage drops below a preset
level or during the normal exercise cycle. To pre-
vent possible injury that might be caused by such
sudden starts, always set the switch to OFF and
remove the fuse before working on or around the
generator or transfer switch. Then, place a “Do
Not Operate” tag on the generator panel and on
the transfer switch.
3.3 AUTOMATIC TRANSFER OPERATION
To select automatic operation, do the following:
1. Make sure the transfer switch main contacts are set
to their “Utility” position, i.e., loads connected to the
utility power source.
2. Be sure that normal utility power source voltage is
available to transfer switch terminal lugs N1 and N2.
3. Set the generator’s Auto/Off/Manual switch to AUTO.
4. Set the generator’s main circuit breaker to its ON
(or closed) position.
With the preceding steps complete, the generator will
start automatically when utility source voltage drops
below a preset level. After the unit starts, loads are
transferred to the standby power source. Refer to
“Sequence of Automatic Operation.”
3.4 SEQUENCE OF AUTOMATIC
OPERATION
The generator’s control panel houses a control logic cir-
cuit board. This board constantly monitors utility
power source voltage. Should that voltage drop below a
preset level, circuit board action will signal the engine to
crank and start. After the engine starts, the circuit
board signals the transfer switch to activate and connect
load circuits to the standby power supply (load terminal
lugs T1/T2 connect to terminal lugs E1/E2).
Upon restoration of utility source voltage above a preset
level, generator circuit board action signals the transfer
switch to transfer loads back to that power supply. After
retransfer, the engine is signalled to shut down.
The actual sequence of operation is controlled by
sensors and timers on a control logic circuit board, as
follows:
A. Utility Voltage Dropout Sensor
• This sensor monitors utility source voltage.
• If utility source voltage drops below about 60 per-
cent of the nominal supply voltage, the sensor ener-
gizes a 15-second timer.
• Once the timer has expired, the engine will crank
and start.
B.Engine Warm-up Time Delay
• This mechanism lets the engine warm up for about
10 seconds before the load is transferred to a stand-
by source.
C.Standby Voltage Sensor
• This sensor monitors generator AC output voltage.
When the voltage has reached 50 percent of the
nominal rated voltage, transfer to standby can
occur.
D.Utility Voltage Pickup Sensor
• This sensor monitors utility power supply voltage.
When that voltage is restored above 80 percent of
the nominal source voltage, a retransfer time delay
starts timing.
E.Retransfer Time Delay
• This timer runs for about 15 seconds.
• At end of a 15-second delay, circuit board action de-
energizes transfer relay in the transfer switch.
• Retransfer to utility power source then occurs.
F. Engine Cool-down Timer
• When the load is transferred back to utility power
source, the engine cool-down timer starts timing.
• The timer will run for about one minute, and the
generator will then shut down.
3.5 ENGINE HEATER
This Generac standby generator comes equipped with a
block heater (Figure 3.2, page 14) that is similar to the
block heaters used in automotive applications. The
block heater must be connected to a customer supplied
120V AC circuit.
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Generac
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Power Systems, Inc. 13
Section 3 — Operation
Guardian Liquid-cooled 40 kW Generator