Generac 86640 - Manual (Page 24)

Test 12< Test DPE Circuit Breaker (Con­
tinued)
PROCEDURE:
1. With the generator shut down, disconnect the leads from
the two breaker terminals, to prevent interaction. Then,
connect the test leads of a volt-ohm-milliammeter (VOM)
across the two circuit breaker terminals. The meter should
read continuity or a very small resistance.
a. If meter indicates 'continuity' or a small resistance, go
to Step 2.
b. If the meter reads 'infinity' replace the circuit breaker.
2. Reconnect the two leads to the circuit breaker terminals.
3. Start the generator engine.
4. Check the generator's AC output voltage (see Test 1).
a. if AC output voltage is excessively low, go to Step 5.
b. If AC output voltage is normal, discontinue tests.
5. Connect a jumper wire across the two terminals of the
excitation (DPE) circuit breaker. Again, check the unit’s AC
output voltage.
RESULTS:
1. In Step 1, if the meter reads 'infinity' it should be replaced.
2. If AC output voltage was excessively low in Step 4, but
normal in Step 5, replace the excitation (DPE) circuit breaker.
Test 13- Test Thermal Protector
DISCUSSION:
Also see 'THERMAL PROTECTOR' on Page 1.1-4. A
thermal protector that has failed open will cause the same
effects as an excitation circuit breaker that has failed open.
PROCEDURE:
RESULTS:
1. If the VOM indicated excitation winding resistance in Step
4, but read 'infinity' in Step 6, the thermal protector will have
to be bypassed as follows:
a. Cut Wire 2 as close as possible to the end of Wire 5.
b. Strip the Insulation from the end of Wire 2 that goes to
the excitation circuit breaker.
c. Strip the iunsulation from the end of Wire 5.
d. Connect the stripped ends of Wire 2 and 5, retain with
the wire nut.
2. If the meter indicated excitation winding resistance In both
Steps 4 and 5, go to Test 14.
Figure 32. Thermal Protector In the Circuit
A. Pictorial B. Schematic
Figure 33. Thermal Protector Bypassed
-.-t
2A
A. Pictorial
CXCrTATtON
^ ^ WINDINO
rr*T)ON I
ÓO
TO EXCrTATION
ClftClHT BBBAKER
B. Schematic
1. Disconnect lead 2 from the excitation circuit breaker.
2. Disconnect lead 6 from the Voltage Regulator.
3. Locate lead 5. This lead is brought out of the Stator and is
unattached. A wire nut covers its end.
4. Connect the test leads of a VOM across leads 5 and 6. The
meter should read a small resistance (the resistance of the
Stator excitation winding).
5. Now, connect the VOM test leads across leads 2 and 6.
Again, the resistance of the Stator excitation windings shouid
be indicated (about 0.73 ohm for 10 kW units; 1.00 ohm for 8
kW units).
Test 14- Test Stator DPE Windings
DISCUSSION:
An open condition in the stator excitation windings wiii
result in loss of excitation output to the Voltage Regulator.
The Regulator will then shut down and generator AC output
voltage will drop to a value commensurate with Rotor residuai
magnetism (about 2-7 volts).
A grounded or shorted condition will also result in prob­
lems with generator AC output. This test will test the Stator
excitation windings for (a) open condition, and (b) for a
grounded condition.
Page 1.6-4