Section 2 Direct Excitation (Brush Type)
Diagnostic Repair Manual
15
AC Diagnostic Tests
Introduction
The Diagnostic Tests in this chapter may be performed in
conjunction with the
Troubleshooting Flow Charts
. Test
numbers in this chapter correspond to numbered tests in
the flow charts.
NOTE:
Test procedures in this manual are not
necessarily the only methods for diagnosing the condition
of components and circuits. All possible methods that
might be used for system diagnosis have not been
evaluated. If any diagnostic method is used other than
the method presented in this manual, the technician must
be sure that neither his personal safety, nor the product's
safety, will be endangered by the procedure or method
that has been selected.
NOTE:
For graphics of different configurations of stators
and the wire numbers associated with different
components, see appropriate wiring diagrams and
schematics for the generator.
Test 1 – Check No-Load Voltage and
Frequency
Procedure
1.
Disconnect or turn OFF all electrical loads
connected to the generator.
2.
Set digital multimeter (DMM) to measure AC
voltage.
3.
Reset all circuit breakers to ON.
4.
Start engine and let stabilize and warm up.
5.
See
. Place meter test leads into an
outlet.
Figure 1-5. DMM Test Leads Connected to a 240 VAC
Receptacle
6.
Read AC voltage.
7.
Connect an AC frequency meter as described in
Step 5.
8.
Read AC frequency.
Results
Refer to flow chart.
Test 2 – Check Main Circuit Breaker
Procedure
The generator has circuit breakers located on the control
panel. If outlets are not receiving power, make sure
breakers are set to ON or “Closed”.
If a breaker is suspected to have failed, test as follows:
1.
Set DMM to measure resistance.
2.
With generator shut down, disconnect all wires
from suspected circuit breaker terminals to prevent
interaction.
3.
See
. With the generator shut down,
connect one meter test lead to one terminal of the
breaker and the other meter test lead to the other
terminal.
4.
Set breaker to ON or “Closed”. The meter should
read CONTINUITY.
5.
Set breaker to OFF or “Open”. The meter should
indicate INFINITY.
Figure 1-6. 20/30 Amp Breaker Test Points
Results
1.
If circuit breaker tests good, refer to flow chart.
2.
If breaker tests bad, replace.
Test 3 – Check Continuity of
Receptacle Panel
General Theory
Continuity of the receptacle panel is important as it
recognizes the receptacle has continuity through the
wiring and is physically connected to the stator. Most
stator winding values are between 0.01 and 0.02 Ohms
of resistance. If a higher than normal ohm reading is
shown, a poor connection could be the problem
preventing that receptacle from receiving power.
240
No Load Voltage
No Load Frequency
223.2 – 256.8 VAC
62.5 – 62.0 Hz
00.01
C.B.
20/30A
