WACKER Group LTC 4 - Checking Stator Windings

Electrical Troubleshooting Procedures LTC Repair
wc_tx000429gb.fm 120
7.28 Checking Stator Windings
See Graphic: wc_gr003097
The generator terminal block is located on top of the generator. When
checking the stator windings at the terminal block, if there is any
evidence of burned windings (such as melted wire insulation or odor),
replace the generator.
Carry out the following tests with the engine shut down.
Note: Before making resistance measurements, determine the value
of your meter’s internal resistance by touching the meter’s leads.
Subtract this value from the values you measure.
7.28.1 Remove the RED, BLACK, and WHITE wires from the generator
terminal block.
7.28.2 Remove the leads from the capacitors and place an insulated
screwdriver across the capacitors to discharge them.
7.28.3 Using the Ohm (resistance) setting on the multimeter, measure the
resistance T1 to T2. Also measure resistance T4 to T5. In both cases
the resistance measured should be 0.36 +0.5/-0.0 Ohms. Measure the
resistance #60 lead to #0 lead. The resistance measured should be 1.7
+0.5/-0.0 Ohms. If there is no continuity (meter reads “OPEN” or “OL”),
replace the stator.
7.28.4 Using the Ohm setting on the multimeter, measure the resistance T1
to ground, and T5 to ground. The multimeter should read “OPEN” or
“OL” for both tests. If the meter does not read “OPEN”, replace the
entire generator.
7.28.5 Using the Ohm scale on the multimeter, measure resistance #60 lead
to ground, #60 lead to T1, and #60 lead to T5. The multimeter should
read “OPEN” or “OL” for all three tests. If the meter does not read open,
replace the entire generator. Consult with factory to confirm.
Note: Do not touch the machine frame when making this test. A
reading error will occur.
Note: A meter reading of 2 megohms (2 M Ohms) or larger is
acceptable.
For a more thorough insulation test, use a megger meter capable of
500 Volts or have a motor repair shop test it. If readings are 2
megohms or greater, the stator is good. If readings are less than 2
megohms, replace the generator end. Consult factory to confirm.