Bryant ASPAS1BBA007, Руководство по диагностике и ремонту

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Page 44
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 Section 2.1.
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:
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.
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" in Section 1.4.
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.
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 in Section 4.3. 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.