TM 9-4940-568-34
5-133
f.
Testing Main Stator.
(1)
Testing Winding Resistance.
(a)
Measure electrical resistance across each pair of stator leads (U1-U2, U5-U6, V1-V2, V5-V6,
W1-W2 and W5-W6) with a Wheatstone bridge or ohmmeter having at least 0.001 ohm precision.
Replace the stator (Para 5-21) if the resistance of any winding is not as specified in Table 5-1.
(b)
Alternatively, winding resistance can be measured line-to-line at the generator terminals (U-V, V-W,
W-U) on “star” connected generators. On a 600 volt generator, line-to-line resistance should be
twice the table value (two winding elements in series). On a “series star” connected generator,
line-to-line resistance should be four times the table value (four winding elements in series). On a
“parallel star” connected generator, line-to-line resistance should be the same as the table value
(two sets of two winding elements in series). Single phase only windings can be measure at W-V
and should be twice the table value.
(2)
Testing Winding Insulation Resistance: Disconnect all stator leads and winding taps from their respective
terminals and make sure the ends do not touch the generator frame. Using an ohmmeter, measure
electrical resistance between any stator lead and the stator laminations. Replace the stator (Para 5-21) if
insulation resistance is less than 1 megohm.
