Generac Power Systems 05176-0 Sequence of Automatic Operation, Automatic Transfer Operation

Section 4 — Operation

Air-cooled 15 kW Generators

4.1USING THE AUTO/OFF/MANUAL SWITCH (FIGURE 4.1)

‹4.1.1 “AUTO” POSITION

Selecting this switch position activates fully automatic system operation. It also permits starting and exercising of the engine every seven days with the exercise timer (see "Generator Test Under Load"). This position also is used for remote starting, when it is set up.

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 “Sequence of Automatic Operation.”

‹4.1.2 “OFF” POSITION

This switch position shuts down the engine. This position also prevents automatic operation.

‹4.1.3 “MANUAL” POSITION

Set the switch to MANUAL to crank and start the engine. Transfer to standby power will not occur unless there is a utility failure.

Figure 4.1 – Generator Control Panel

4.3SEQUENCE 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).

FUSE
5A	OFF MAN.
AUTO
FUSE
15A	SET
	EXERCISE
	TIME

L o c a t e y o u r n e a r e s t d e a le r a t :

POWER SYSTEMS, INC.

SYSTEM SET

LOW OIL

HIGH TEMP.

OVER SPEED

OVER CRANK

F L A S H IN G G R E E N L E D =

N O U T IL IT Y S E N S E 4 F L A S H IN G R E D L E D S =

E X E R C IS E R N O T S E T

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 70

percent of the nominal supply voltage, the sensor

energizes a 15-second timer.

• Once the timer has expired, the engine will crank

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 both fuses 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.

4.2AUTOMATIC 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 connected to the utility power source (Figure 4.2).

2.Be sure that normal utility power source voltage is available to transfer switch terminal lugs N1

14

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.