Generac Power Systems 04759-0 Automatic Transfer Operation, Sequence of Automatic Operation

Section 3 — Operation

Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

8.Turn ON the utility power supply to the transfer switch, which will allow the transfer switch to transfer back to utility power. The unit will con- tinue to run for one minute and then shut down.

9.Allow the unit to cool.

10.Drain the oil and remove the oil filter. Replace the oil filter according to Section 4.4, “Changing the Oil Filter” (Page 18). Replace the oil with synthet- ic oil as recommended in Section 4.3, “Changing the Engine Oil” (Page 17).

11.The generator is now ready for service.

3.2USING THE AUTO/OFF/MANUAL SWITCH (FIGURE 3.1)

‹3.2.1 “AUTO” POSITION

Selecting this switch position activates fully automatic system operation. It also allows you to start and exercise the engine every seven days with the setting of the exer- cise timer (see Section 3.6, Page 16). This position also is used for remote starting, when it is set up.

‹3.2.2 “OFF” POSITION

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

‹3.2.3 “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 3.1 – Generator Control Panel

FUSE

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.
5A	SYSTEM SET
AUTO OFF MAN.

LOW OIL

3.3AUTOMATIC 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 3.2, Page 15).

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.”

3.4SEQUENCE 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 connect load circuits to the standby power sup- ply (load terminal lugs T1/T2 connect to terminal lugs E1/E2).

Upon restoration of utility source voltage above a pre- set 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:

FUSE		HIGH TEMP.
		OVER SPEED
		OVER CRANK
15A	SET	F L A S H IN G G R E E N L E D =
	EXERCISE	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 =
	TIME	E X E R C IS E R	N O T S E T

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 gen- erator panel and on the transfer switch.

A.Utility Voltage Dropout Sensor

•This sensor monitors utility source voltage.

•If utility source voltage drops below about 70 per- cent 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.

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