Erratic Voltage Regulation; Separate Excitation - Kohler Power Systems 8RESV Service Manual

5.3.2

Erratic Voltage Regulation

Dramatic variations in the alternator voltage (more than
5 VAC) while the generator is operating at a steady load
may cause flicker. Connect a flicker lamp to the
generator output to determine if the generator is
producing flicker. If flicker is observed, it can be caused
by any of the following:
Engine speed fluctuation. Refer to Sections 5.10 and
D
5.11 for troubleshooting.
Alternator fault. Refer to Sections 5.4 and 5.5 for
D
troubleshooting.
Outer loop gain too high. Refer to Section 5.9.
D
Internal controller stability circuit failure, indicated by
D
excessive throttle movement, excessive voltage
fluctuation, and dramatic flicker.
TP-6881 7/15
5.3.3

Separate Excitation

Use the following procedure to separately excite the
generator using an external voltage source (a 12-volt
automotive battery).
Separately exciting the generator can identify faulty
voltage regulation by the controller or reveal a running
fault in the rotor and/or stator. An external power source
duplicates the role of the voltage regulator and excites
the generator field (rotor). A generator component that
appears to be in good condition while stationary may
exhibit a running fault (open or short circuit) while
moving. Centrifugal forces acting on the windings
during rotation may cause a broken circuit to open.
Increasing temperatures can cause the insulation to
break down, resulting in a running fault. If this test
shows that the rotor and stator are in good condition,
test the voltage regulation using the tests in Section 5.8.
WARNING
Hazardous voltage.
Can cause severe injury or death.
Operate the generator set only when
all guards and electrical enclosures
are in place.
Testing live electrical circuits.
current can cause severe injury or death. Have trained and
qualified personnel take diagnostic measurements of live
circuits. Use adequately rated test equipment with electrically
insulated probes and follow the instructions of the test
equipment manufacturer when performing voltage tests.
Observe the following precautions when performing voltage
tests: (1) Remove all jewelry. (2) Stand on a dry, approved
electrically insulated mat. (3) Do not touch the enclosure or
components inside the enclosure. (4) Be prepared for the
system to operate automatically.
(600 volts and under)
Grounding electrical equipment. Hazardous voltage can
cause severe injury or death. Electrocution is possible
whenever electricity is present. Ensure you comply with all
applicable codes and standards.
generator set, transfer switch, and related equipment and
electrical circuits. Turn off the main circuit breakers of all
power sources before servicing the equipment. Never contact
electrical leads or appliances when standing in water or on wet
ground because these conditions increase the risk of
electrocution.
Short circuits. Hazardous voltage/current can cause
severe injury or death. Short circuits can cause bodily injury
and/or equipment damage.
connections with tools or jewelry while making adjustments or
repairs. Remove all jewelry before servicing the equipment.
Section 5 Component Testing and Adjustment
Moving parts.
Hazardous voltage or
Electrically ground the
Do not contact electrical
77