Mobile Generator Output Voltage Troubleshooting
wc_tx000726gb.fm 77
8.9 Checking Stator Windings at the Lugs
Prerequisites Generator shut down
Two alligator clips each connected to 12 inches of 14-gauge wire
Procedure Follow the procedure below to check the stator windings at the lugs.
1. Place the voltage selector switch in the 480/277 position.
2. Open the lug door. Connect the alligator clips/wires to Lug 1 and to the neutral lug (N).
3. Close the lug door and place the main circuit breaker in the ON (closed) position.
4. Measure the resistance between Lug 1 and the neutral lug. Enter the reading in the
table below. Also measure the resistance between Lug 2 and the neutral lug, and lug 3
and the neutral lug. Enter these values in the table below.
5. Measure the resistance between Lug 1 and Lug 2; Lug 1 and Lug 3; and Lug 2 and
Lug 3. Enter these values into the table below. All values are in Ohms.
Are your readings approximately equal to the ideal measurements?
The stator windings have now been checked at the lugs. Continue with Checking the Recti-
fier Diodes.
480/277 posi-
tion
L1–N L2–N L3–N L1–L2 L2–L3 L1–L3
Ideal 0.2 0.2 0.2 0.4 0.4 0.4
Your reading
Yes____ No____
The main stator win-
dings and the voltage
selector switch are
OK.
1. Clean the voltage selector switch with contact cleaner.
2. Check the windings at the generator.
See Checking Stator Windings at the Voltage Selector Switch.
1000
200
20
2
200m
F
V
A
V- COM
1000
200
20
2
200m
F
V
A
V- COM
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