Guardian Technologies 04760-2 Manual De Usuario

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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 (Figure 3.2).

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 
Section 3.4, “Sequence of Automatic Operation.”

The generator’s control panel houses a control logic 
circuit board. This board constantly monitors util-
ity 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 acti-
vate 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 

percent of the nominal supply voltage, the sensor 
energizes 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 standby source.

C. Standby  Voltage  Sensor 

• This sensor monitors generator AC output volt-

age. 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 volt-

age. When that voltage is restored to above 70 
percent of the nominal source voltage, a retrans-
fer 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 the 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.

To start the generator and activate the transfer switch 
manually, proceed as follows:

1.  Set the generator’s main circuit breaker to its 

OFF (or open) position.

2.  Set the generator’s AUTO/OFF/MANUAL switch to 

OFF.

3.  Turn OFF the utility power supply to the transfer 

switch using the means provided (such as a utility 
main line circuit breaker).

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