Generac Power Systems GUARDIAN 04137-0 - Manual (Page 11)

Section 2 ~ Operation
Guardian Liquid-cooled 8 kW Generators
OPERATiON
(pix
^ 2.3.2 "OFF" POSITION
This switch position shuts down the engine. This
position also prevents operation.
# 2.3.3 "MANUAL" POSITION
Set the switch to Manual to crank and start the
engine. Transfer to standby power will not auto-
maticallv occur unless there is a utility failure.
-A WARMING A-
2.4
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 pre­
set level or during the normal exercise cycle. To
prevent 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.
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 con­
nected to the utility power source.
2. Be sure tfiat normal utility power source voltage is
available to transfer switch terrninal lugs N1 and
N2. {See the electrical data in the applicable trans­
fer switch manual.)
3. Set the generator’s Auto/Otl/Manuai 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.”
2.5 SEQUENCE OF
AUTOMATIC OPERATION
The generator’s control panel houses a control logic
circuit board. This board constantly monitors utlli-
bv* power source voltage. Should tiiat voltage drop
below a preset level, circuit board action will signal
the engine to crank and stmt. .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). (See tlie electrical data in tire
applicable transfer switch manual.)
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 sig­
nalled 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
o This sensor monitors utility source voltage.
® If utility source voltage drops below about 60
percent of the nominal supply voltage, the sen­
sor energizes a 15-second timer.
® Once the timer has expired, the engine v/ill
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 standby source.
C. Standby Voltage Sensor
» This sensor monitors generator .EC output volt­
age. 'Wlien the vtytage has reached 50 percent
of the nom.incJ rated voltage, transfer to stand­
by can occur.
D. Utiliw Voltage Pickup Sensor
® This sensor monitors utillbv power supply volt­
age, When that voltage is restored above SO per­
cent of the nominal source volta.ge, a retrcmsfer,
time delay starts timing,
E. Retransfer Time Delay
= This timer runs for about 15 seconds.
® AT end of a 15-second delay, circuit board
acrioii de-energizes transfer relay in the trans­
fer switch.
» Retransfer to utility power source tlien occurs.
F. Engine Cool-down Timer
• When the load is transferred back to utility"
power source, tihe engine cool-down timer
starts timing,
• The timer will run for about one minute, and
the generator will then shut down.
Generac® Power Systems, Inc.