Test 4 - Fixed Excitation Test/Rotor Amp Draw Test - Generac Power Systems GP Series Diagnostic Repair Manual

Section 1 AC Diagnostic Tests
Results
If any other reading than CONTINUITY was
1.
measured, further troubleshooting needs to be done
to determine if it is the receptacle or the wiring.
If receptacles test good, refer to flow chart.
2.
0.01 Ohms
Figure 3-3. Checking Continuity of Receptacles
Test 4 – Fixed Excitation Test/Rotor
Amp Draw Test
General Theory
Supplying a fixed DC current to the rotor will induce a
magnetic field in the rotor. With the generator running,
this should create a proportional voltage output from the
stator windings.
NOTE: A standard 12 Volt battery is needed for this
procedure.
NOTE: Always use the unit specific schematics and
wiring diagrams for brush orientation.
AVR SENSING
WHITE S15 2 BLUE
GREEN S16 6 BLUE
Figure 3-4. Jumper Wires Between Battery and Brush Assembly
10
002967
C1 FEMALE
DPE
BRUSH ASSEMBLY
AVR
Procedure
Remove positive and negative wires connected to
1.
the brush assembly.
Connect one jumper wire to where the positive
2.
brush wire was connected on the brush assembly.
Connect another jumper wire to where the negative
3.
brush wire was connected on the brush assembly.
NOTE: For safety, install an in-line fuse in the positive
jumper wire. Maximum fuse should be 2 amps.
Set DMM to measure AC Voltage.
4.
See Figure 3-4. Connect meter test leads across
5.
the 240 VAC receptacle so the leads read line-to-
line voltage.
Set RUN-STOP switch to RUN and start unit.
6.
While the unit is running connect one jumper wire
7.
to the negative terminal of the battery and connect
the other jumper wire to the positive terminal.
Record the voltage measured on the 240 VAC
8.
receptacle panel. Approximately 130 VAC should
be measured. If no voltage is measured, connect
meter test leads across R1 and L2 at the stator
connection terminal strip.
Set RUN-STOP switch to STOP.
9.
Disconnect meter leads from 240 VAC receptacle.
10.
See Figure 3-5. Connect one meter test lead to
11.
Wire 2 and the other meter test lead to Wire 6 on
the C1 female connector.
Set RUN-STOP switch to RUN and start unit.
12.
12 VOLT
BATTERY
130 VAC
240 VAC
RECEPTACLE
FUSE
(+)
(-)
Diagnostic Repair Manual
004979