Guardian Technologies 005283 Manual De Usuario

 16 

1.  990 engines have an electric choke in the air box 

that is automatically controlled by the electronic 
control board.

2.  530 engines have an electric choke on the divider 

panel air inlet hose that is automatically con-
trolled by the electronic control board.

3.  410 engines do not have a choke.

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 (Figure 3.2).

2.  Be sure that normal UTILITY power source volt-

age is available to transfer switch terminal lugs 
N1 and N2 (Refer to the Electrical Data section).

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 the 
Sequence of Automatic Operation section.

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). 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 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:

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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 trans-
ferred to the 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 above 75 per-
cent 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 tim-
ing.

• 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 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).

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