Guardian Technologies 4760, 4456, 4390, 4389, 4759, 4758 Test 13 Check and Adjust Voltage Regulator

SECTION 2.4

DIAGNOSTIC TESTS

PART 2

AC GENERATORS

TEST 13 - CHECK AND ADJUST

VOLTAGE REGULATOR

DISCUSSION:

For additional information, refer to description and components Page 2.1-3.

PROCEDURE:

With the frequency between 61-62 Hertz, slowly turn the slotted potentiometer (Figure 12) until line voltage reads 244-252 volts.

NOTE: You must remove the access panel on top of the control panel to adjust the voltage regulator.

NOTE: The voltage regulator is housed above the generator control panel. The regulator maintains a voltage in direct proportion to frequency at a 2-to-1 ratio. For example, at 62 Hertz, line-to-neutral voltage will be 124 volts.

Figure 12. Voltage Adjustment Potentiometer

RESULTS:

PROCEDURE:

1.Connect an accurate AC frequency meter and an AC voltmeter across the stator AC power winding leads.

2.Start the engine, let it stabilize and warm-up.

3.Apply electrical loads to the generator equal to the rated capacity of the unit.

4.Check the AC frequency and voltage. Frequency should not drop below approximately 58-59 Hertz. Voltage should not drop below about 230 volts (plus or minus 2 percent).

RESULTS:

1.If frequency and voltage drop excessively under load, go to Test 15.

2.If frequency and voltage under load are good, discontinue tests.

TEST 15 - CHECK FOR OVERLOAD CONDITION

DISCUSSION:

An "overload' condition is one in which the generator rated wattage/amperage capacity has been exceeded. To test for an overload condition on an installed unit, the best method is to use an ammeter. See "Measuring Current" on Page 1.4-2.

PROCEDURE:

Use a clamp-on ammeter to measure load current draw, with the generator running and all normal electrical loads turned on.

RESULTS:

1.If the unit is overloaded, reduce loads to the unit's rated capacity.

2.If unit is not overloaded, but rpm and frequency drop excessively when loads are applied, go to Test 16.

1.If the frequency and voltage are now good, discontinue tests.

2.If frequency is now good but voltage is high or low, go to Problem 1, Test 4.

TEST 14 - CHECK VOLTAGE AND

FREQUENCY UNDER LOAD

DISCUSSION:

It is possible for the generator AC output frequency and voltage to be good at no-load, but they may drop excessively when electrical loads are applied. This condition, in which voltage and frequency drop excessively when loads are applied, can be caused by (a) overloading the generator, (b) loss of engine power, or (c) a shorted condition in the stator windings or in one or more connected loads.

TEST 16 - CHECK ENGINE CONDITION

DISCUSSION:

If engine speed and frequency drop excessively under load, the engine may be under-powered. An under-powered engine can be the result of a dirty air cleaner, loss of engine compression, faulty carburetor settings, incorrect ignition timing, etc.

PROCEDURE:

For engine testing, troubleshooting and repair procedures refer to Problem 11 on Page 4.3-3. For further engine repair information refer to the following manuals:

•P/N 0C1103 - Service and Repair Manual for Single Cylinder GN Engines.

•P/N 0E2081 - Service Manual for GTV-990/760 V-Twin OHVI Engines.

Page 2.4-10