Sequence Of Automatic Operation; Manual Transfer Operation - Generac Power Systems Guardian 005240 Installation And Owner's Manual

Operation
3.3 SEQUENCE OF AUTOMATIC
OPERATION
The generator's control panel houses a control logic circuit 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 con-
nect load circuits to the standby power supply (load terminal lugs
T1/T2 connect to terminal lugs E1/E2). Refer to the Electrical Data
section.
The generator must run at 50 Hz or greater for the transfer output
to be activated. Once activated, it will remain active even if the
frequency dips below 50 Hz.
Upon restoration of utility source voltage above a preset level,
generator circuit board action signals the transfer switch to trans-
fer 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 65 percent of the
nominal supply voltage, the sensor energizes a 10 second
timer.
• Once the timer has expired, the engine will crank and start if
utility is still low.
B. Engine Warm-up Time Delay
• This mechanism lets the engine warm up for about five
(5) seconds before the load is transferred to the standby
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 75 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 if utility is still present.
• 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.
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3.4 MANUAL TRANSFER
OPERATION
3.4.1 TRANSFER TO GENERATOR
POWER SOURCE
To start the generator and activate the transfer switch manually,
proceed as follows:
1. Set the generator's AUTO/OFF/MANUAL switch to OFF.
2. Set the generator's main circuit breaker to its OFF (or OPEN)
position.
3. Turn OFF the utility power supply to the transfer switch
using the means provided (such as a utility main line circuit
breaker).

Do not attempt to activate the transfer switch
manually until all power voltage supplies to
the switch have been positively turned off.
Failure to turn off all power voltage supplies
may result in extremely hazardous and pos-
sibly fatal electrical shock.
4. Use the manual transfer handle inside the transfer switch to
move the main contacts to their STANDBY position, i.e., loads
connected to the standby power source (Figure 3.2).
5. To crank and start the engine, set the AUTO/OFF/MANUAL
switch to MANUAL.
6. Let the engine stabilize and warm up for a few minutes.
7. Set the generator's main circuit breaker to its ON (or CLOSED)
position. The standby power source now powers the loads.
Figure 3.2 – Manual Transfer Switch Operation