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Airgap
* Check airgap at four quadrature positions and recenter rotor if necessary. On
horizontal machines, the bearings may need replacing if the bottom airgap is
appreciably smaller than the top.
appreciably smaller than the top.
Air Fans
* Check rotor air fans for fatigue cracks. Check and tighten holding bolts and screws.
Windings
* Inspect for damaged insulation, dirt, oil, or moisture. Blow out dust with clean, dry
air at pressure not exceeding 40 pounds per square inch. Clean exposed parts of
windings thoroughly with a noninflammable solvent using suitable brushes for
hard-to-reach places. The use of carbon tetrachloride is not recommended because
of the toxic hazard. Revarnish windings if insulation is becoming hard, brittle, or
dull. Check for insulation deterioration such as tape separation, cracking,
brittleness, or evidence of corona. Check insulation with high-voltage direct current
method. (See FIST Volume 3-1, Testing Solid Insulation of Electrical Equipment.)
windings thoroughly with a noninflammable solvent using suitable brushes for
hard-to-reach places. The use of carbon tetrachloride is not recommended because
of the toxic hazard. Revarnish windings if insulation is becoming hard, brittle, or
dull. Check for insulation deterioration such as tape separation, cracking,
brittleness, or evidence of corona. Check insulation with high-voltage direct current
method. (See FIST Volume 3-1, Testing Solid Insulation of Electrical Equipment.)
Banding and Lashing
* Check wire and string banding on direct-current armature windings. Check end-
turn lashing of alternating current stator coils. Apply lashing if end turns vibrate
excessively.
excessively.
Slot Wedges
* Check slot wedges and replace loose ones. Tighten coils in slots by rewedging, if
necessary.
necessary.
Commutator or Collector Rings
* Daily Check commutator or collection rings and brush operation. Wipe
commutator or rings if needed. Have brushes replaced if worn too short.
Brushes and Brush Rigging
* Turn down, stone, or polish commutator or collector rings if grooved, rough, or
eccentric. Undercut mica if high. If commutator or rings have a good polish, they
should not be disturbed. Check brush spring tension and brush fit. Tighten bolts,
screws, and connections. Reset brush holders if not properly spaced. Check brush
neutral position. Replace and sand in new brushes if needed. Clean up carbon or
metallic dust.
should not be disturbed. Check brush spring tension and brush fit. Tighten bolts,
screws, and connections. Reset brush holders if not properly spaced. Check brush
neutral position. Replace and sand in new brushes if needed. Clean up carbon or
metallic dust.