Table 5-1. DS and GS Troubleshooting
TEST OR INSPECTION
1. GENERATOR FAILS TO BUILD UP RATED VOLTAGE
Check to see if the field flash switch is broken or cracked. Test as follows: Using a multimeter,
check for continuity of the switch contacts. Test the field flash switch for continuity while the
switch is held in the closed (ON) position.
If the field flash switch is damaged or defective replace it. Refer to paragraph 7-4 for removal
and installation. If the switch is not defective, go on to Step 2.
Test for a defective resistor as follows:
a. Disconnect the current transformer leads and remove the three resistors.
Never disconnect the leads of a current transformer, either at the transformer or at
a meter connected to the transformer, when the equipment is energized. The three
resistors used with this equipment are connected across the secondary windings of
the current transformer and they ordinarily prevent an open circuit condition. But,
if a resistor were to fail and then the secondary was to be open circuited by discon-
necting its load (the meter), extremely high voltages would be induced in the windings.
Serious damage to the equipment and possibly the death of personnel could result.
b. Use a multimeter set on the RX1 scale and test between terminals A1 and A2, B1 and B2,
arid Cl and C2. Continuity should be shown in all three tests.
c. Now, test between terminal A1 and B1, between A1 and C1, and between B1 and C1. There
should be no continuity indicated in any of these three tests.
d. Connect the multimeter, in turn, across the terminals of each resistor and measure the
resistance. The resistance should measure within one percent above or below 305 ohms.
If test shows resistors are defective, replace them. Refer to paragraph 7-5 for removal and
installation of the resistors. If the malfunction is not caused by faulty resistors, go on to
Determine if the voltage regulator is defective by performing voltage regulator on-equipment
test as described below.
a. Put output selector switch to desired output setting (fig. 2-4) and disconnect the load cables.
b. Start the generator set (fig 2-7 or fig. 2-8). Place the circuit breaker to the ON position and
check output selector switch to indicate load terminals where output voltage is applied.
c. Check set voltmeter for correct setting. Using a multimeter, check load terminals to verify
reading on set voltmeter. If voltage is low and the variable resistor on the control panel will not
correct the deficiency, check exciter voltage across terminals 20 and 21 of the voltage regulator
terminal board. This voltage will vary but should be about 30 volts. If voltage at terminals 20
and 21 of the voltage regulator terminal board fails to meet specifications, the voltage regulator
is defective and should be replaced.
d. Using a multimeter as a check against the set voltmeter, test the output terminals of the
generator set against all position settings of the voltage switch.
Stop the generator set and connect the load cables.
Repeat steps 2 and 3 above.
If the regulator is faulty replace it. Refer to figure 7-3 for voltage regulator with PN
13211E6975 (97403) or 13212E8950 (97403) and to figure 7-4 for voltage regulator PN
13219E0883 (97403). Refer to paragraph 7-6 for removal and installation instructions. If faulty
voltage regulator is not the cause of the malfunction, go on to Step 4.