TROUBLESHOOTING
TESTING AND ADJUSTING
POSSIBLE CAUSES
VERIFICATION PROCEDURE
(Continued)
voltage. If the stability of the voltage and rpm are the same as
before, the problem is in the engine (governor).
NOTE: The generator name plate shows the maximum excitation
voltage for full load. At no load, the correct excitation voltage is
approximately 25% of the number on the generator nameplate.
42. Damping Resistor Open (R5)
Disconnect damping resistor (R5) by removing wire (12) between
damping resistor (R5) and suppression capacitor (C2). Check
resistance of (R5) from wire (12) to terminal (26). Typical
resistance is approximately 10 ohms.
43. Temporary Short Circuit in RFI
Disconnect the RFI suppression capacitor (C1) by removing the
Suppression Capacitor (C1)
spade terminal connection of wire (6). Start the engine and look
for voltage stability. If voltage is not correct, remove (C1) and
install a new capacitor.
44. Temporary Short Circuit in
Disconnect suppression capacitor (C2) by removing spade terminal
Suppression Capacitor (C2)
connection of wire (6). Start the engine and look for voltage
stability. If voltage is not correct, remove (C2) and install a new
capacitor.
To check suppression capacitor (C2), measure the resistance. A
resistance measurement of anything but infinity shows that the
suppression capacitor (C2) is defective. If the resistance is infinity
connect 120V AC, 60 Hz, across the terminals. Current must be
approximately one amp.
NOTE: Install a 10 amp fuse in the 120V AC, 60 Hz, circuit. This
is to be a safety limit if the capacitor is defective.
45. Current in Exciter Field (L3) is
With the engine stopped, disconnect wire F1 from terminal F1.
not Stable
Connect the positive cable from a DC ammeter to terminal Fl.
Connect the negative cable to wire F1.
NOTE: The DC ammeter must have a capacity of 15 amps or more.
Start the engine. The DC current in the exciter field (L3) must
increase to a value less than 15 amps and remain constant.
46. Defect in Voltage Level
With engine stopped, disconnect wire (7) from spade terminal (4)
Rheostat (R2)
of module (A1). Measure the resistance between wire (7) and
spade terminal (6) of module (A1). This is the resistance of the
voltage level rheostat (R2). The resistance with the voltage level
rheostat (R2) fully clockwise is 0 ohms. The resistance is 500
ohms at fully counterclockwise. The resistance must change
smoothly as the adjustment of the voltage level rheostat (R2) is
changed between these points.
47. Defect in Voltage Droop
With the engine stopped, disconnect wire (5) from terminal (5) on
Potentiometer (R1)
module (A1). Measure the resistance between wire (5)and
terminal (6) on the module (A1). Resistance with the voltage
droop potentiometer (R1) fully counterclockwise is 0 ohms. The
resistance is 8 ohms at fully clockwise. The resistance must change
smoothly as the adjustment of the voltage droop potentiometer
(R1) is changed between these points.
70
