Generac Power Systems CorePower 6/7 kW 60 Hz Diagnostic Repair Manual page 39

AC GENERATORS
Table 8. Test Points – Shorted Condition (CorePower)
Test Point A
C1 Pin 1 (Blue Wire)
C1 Pin 1 (Blue Wire)
Table 9. Test Points – Shorted Condition (PowerPact)
Test Point A
Stator Lead (Wire 22)
Stator Lead Blue (Wire 2)
Stator Lead Blue (Wire 6)
Table 10. Stator Test Results - CorePower
Test Point A Test Point B
Resistance Tests
Stator Lead Blue Wire Stator Lead Black Wire
Stator Lead Blue Wire C1 Pin 3 (White Wire)
Stator Lead Blue Wire C1 Pin 4 (Green Wire)
Shorts to Ground
Ground Stator Lead Blue Wire
Ground Stator Lead Black Wire
Ground C1 Pin 1 Wire 44 (Blue Wire)
Ground C1 Pin 4 (Green Wire)
Shorted Condition
C1 Pin 1 (Blue Wire) Stator Lead Blue Wire
Table 11. Stator Test Results - PowerPact
Test Point A Test Point B
Resistance Tests
Stator Lead Blue (Wire 2) Stator Lead Blue (Wire 6)
Stator Lead (Wire 22) Stator Lead (Wire 11)
Stator Lead (Wire 22) Stator Lead (Wire S1)
Stator Lead (Wire 11) Stator Lead (Wire S1)
Stator Lead (Wire 33) Stator Lead Blue (Wire 44)
Stator Lead (Wire 33) Stator Lead Blue (Wire S2)
Stator Lead (Wire 44) Stator Lead Blue (Wire S2)
Shorts to Ground
Ground Stator Lead Blue Wire
Ground Stator Lead (Wire 11)
Ground Stator Lead (Wire 44)
Ground Stator Lead (Wire S1)
Ground Stator Lead (Wire S2)
Shorted Condition
Stator Lead (Wire 22) Stator Lead (Wire 44)
Stator Lead Blue (Wire 6) Stator Lead (Wire 33)
Note: These results may be needed when requesting factory
support.
PART 2
Test Point B
Stator Lead Blue Wire
Stator Lead Black Wire
Test Point B
Stator Lead (Wire 44)
Stator Lead (Wire 33)
Stator Lead (Wire 22)
Results
Results
Note: Stator winding resistance values are very low and
some VOM's will not read such a low resistance, and will
simply indicate CONTINUITY. The manufacturer recommends
a high quality digital type meter capable of reading a very
low resistance.
Results
1. Resistance Test: If the VOM indicated a very high resistance
or INFINITY, the windings are open or partially open.
2. Grounded Condition: Any resistance value other than
INFINITY indicates a grounded winding.
3. Shorted Condition: Any resistance value other than INFINITY
indicates a shorted winding.
Note: If the winding tests good, perform an insulation
resistance test. If the winding fails the insulation resistance
test (using a meg-ohm-meter), clean and dry the stator. Then,
repeat the insulation resistance test. If the winding fails the
second resistance test (after cleaning and drying), replace
the stator assembly.
TEST 11 – CHECK AC OUTPUT VOLTAGE
Discussion
A Volt-Ohm-Meter (VOM) may be used to check the generator
output voltage. Output voltage may be checked at the unit's main
circuit breaker terminals. Refer to the unit's DATA PLATE for rated
line-to-line and line-to-neutral voltages.
DANGER! Use extreme caution during this test. The

generator will be running. High and dangerous voltages
will be present at the test terminals. Connect meter test
clamps to the high voltage terminals while the generator
is shut down. Stay clear of power terminals during the
test. Make sure meter clamps are securely attached and
will not shake loose.
Procedure
1. With the engine shut down, connect the AC voltmeter test
leads across the 11 (Blue) and 44 (Black) wire terminals of
the generator main circuit breaker. These connections will
permit line-to-line voltages to be read.
2. Set the generator main circuit breaker to its OFF or "Open"
position. This test will be conducted with the generator
running at no-load.
3. Start the generator, let it stabilize and warm up for a minute
or two.
4. Take the meter reading. On unit's having a rated line-to-line
voltage of 240 volts, the no-load voltage should be about
242-252 volts AC.
5. Shut the engine down and remove the meter test leads.
Results
1. If zero volts or residual voltage is indicated, proceed to Test 4.
Section 2.4
Diagnostic Tests
Page 37