Test 9 - Check Capacitor - Generac Power Systems 10 kW LP Repair Manual

sEctioN 2.4
DiaGNostic tEsts
• An open circuit condition
• A "short-to-ground" condition
• A short circuit between windings
note: the resistance of stator windings is very low.
Some meters will not read such a low resistance,
and will simply indicate continuity. recommended
is a high quality, digital type meter capable of read-
ing very low resistances.
PROCEDURE, 8 kW:
1. Disconnect Stator Leads 11 and 44 from the main circuit
breaker.
2. Disconnect Stator Leads 22 and 33 from the neutral
connection separate the leads.
3. Make sure all of the disconnected leads are isolated
from each other and are not touching the frame during
the test.
4. Set a VOM to measure resistance.
5. Connect one test lead to Stator Lead 11. Connect the
other test lead to Stator Lead 22. Note the resistance
reading and compare to the specifications in the front of
this manual.
6. Connect one test lead to Stator Lead 33. Connect the
other test lead to Stator Lead 44. Note the resistance
reading and compare to the specifications in the front of
this manual.
PROCEDURE, 10 kW:
1. Isolate the generator from the transfer switch by dis-
connecting the load wires from the main breaker inside
the generator.
2. Disconnect Stator Leads 22 and 33 from the neutral
connection and separate the leads.
3. Make sure all of the disconnected leads are isolated
from each other and are not touching the frame during
the test.
4. Turn the Main Breaker to the "ON" or CLOSED position.
5. Set a VOM to measure resistance.
6. See Figure 4 for proper testing points. Connect one
meter test lead to Wire 11 on the load side of the main
breaker. Connect the other meter test lead to Wire 22
(power winding). Note the resistance reading and com-
pare to the specifications in the front of this manual.
7. Connect one test lead to Stator Lead 44 on the load
side of the main breaker. Connect the other test lead
to Stator Lead 33 (power winding). Note the resistance
reading and compare to the specifications in the front of
this manual.
Page 46
Part 2
note: Wire 11 and Wire 44 could be switched on
the main breaker. if an inFinity reading is indi-
cated try putting the meter leads on the other
output terminal of the breaker. if inFinity is still
read then an actual fault may exist.
TEST WINDINGS FOR A SHORT TO GROUND:
7. Make sure all leads are isolated from each other and are
not touching the frame.
8. Connect one test lead to a clean frame ground. Connect
the other test lead to stator lead Wire 11.
a. The meter should read INFINITY.
b. Any reading other than INFINITY indicates a
"short to ground" condition.
9. Repeat Step 7 using stator lead 44
TEST FOR A SHORT CIRCUIT BETWEEN WINDINGS:
10. Connect one test lead to stator lead 11. Connect the
other test lead to stator lead 33.
a. The meter should read INFINITY.
b. Any reading other that INFINITY indicates a
short between windings.
11. Repeat Step 10 using Wire 44.
RESULTS:
1. Stator winding resistance values is a test of winding conti-
nuity and resistance. If a very high resistance or INFINITY
is indicated, the winding is open or partially open.
2. Testing for a "grounded" condition: Any resistance
reading indicated the winding is grounded.
3. Testing for a "shorted" condition: Any resistance reading
indicated the winding is shorted.
4. If stator tests good and wire continuity tests good, refer
back to flow chart.
teSt 9 – check capacitor
DISCUSSION:
The brushless rotor system relies on the charging and
discharging of a capacitor to induce voltage into the
rotor and also to regulate voltage once 240 VAC is
achieved. If the capacitor fails, only residual magnetism
of the rotor will be measured at the Main Breaker.
*
Danger: the capacitor may need to be dis-
charged before testing. a capacitor can be
discharged by crossing the terminals with
a metal insulated screw driver.
*
Danger: use proper protective equipment
when dealing with a capacitor that has
exploded.
AC GENERATORS