Section 3 — Operation
3.1.4 CHOKE OPERATION
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.
3.2AUTOMATIC 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 (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.
3.3SEQUENCE 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). 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:
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
•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
•Retransfer to utility power source then occurs.
F.Engine
•When the load is transferred back to utility power source, the engine
•The timer will run for about one minute, and the generator will then shut down.
3.4MANUAL 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).
DANGER
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 possibly fatal elec- trical shock.
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