What are the works to be done in generator in major overhauling?

1 Answer

Answer :

Works on stator
a) Hydro test (DM water at 5 kg/cm2 pressure, leak acceptable is 5% for 24 hrs).
b) Hydro test of H2 coolers (DM water at 4 kg/cm2 for 30 seconds no leak is
allowed)
c) Pneumatic test with mask air.
d) Drying out of stator conductor. Hot air blower is used.
e) IR value check.
f) Stator overhang portion inspection.
g) Inspection of Teflon tubes and rubber grummets.
h) Stator wedge tightness test with 200 grams hammer.
i) Inspection of RTD’s.
j) Maintenance of end shields.
k) Hot air and hot water test of stator conductors to check whether flow through all
stator conductors is uniform.
l) Measurement of IR and PI value.
m) Capacitance and tan-delta measurements.
n) Partial discharge test.
o) Winding resistance measurement.
p) DC step voltage.
q) ELCID (electromagnetic core imperfection detection) test. 

Works on Rotor
a) Nitrogen leak tightness test of CC bolts at 4 kg/cm2.
b) Inspection of rotor slots.
c) Purge test of rotor ventillation canals.
d) DP test on slip-ring hub to detect micro crack.
e) DP and Ultrasonic test on retaining rings to detect any cracks.
f) Measurement of IR and PI value.
g) Impedance measurement.
h) Recurrence surge oscillograph.
i) Winding resistance measurement.
j) Slip-ring groove cutting and machining.
k) Patina formation. Then OCC test. 

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