Man Hours 6
Special Instructions:
1. Schedule shutdown with operating personnel as necessary.
2. Coordinate this maintenance with the motor controller and
the driven equipment.
3. Some units require removal of access screens or plates.
4. Review manufacturer's instructions.
5. De-energize, tag, and lock out power circuits.
6. Ground electrical circuits in the unit prior to cleaning or servicing to
discharge any capacitors.
7. Record and report deficiencies.
8. Cleaning: Without disturbing adjacent areas or redistributing dirt, dust,
and contaminants, use a small vacuum cleaner to enter into narrow openings,
such as end bells, ventilation ports, etc.
10. Do not spray liquid solvents onto motor windings. If solvents must be used,
only those approved for electric motor cleaning should be used. Wipe with
damp but not wet rags. Several wipings may be required for heavily soiled
areas.
11. Lubrication: Use lubricants specified by the manufacturer only, or get
approval from the regional office for substitutes.
Items to Check & Initial Completion:
1. All Motors:
a.___ Clean ventilation ports of accumulations of dirt, dust, and other
foreign material with vacuum cleaner (see special instruction no. 7).
b.___ Closely examine condition of all motor covers, screens, protective
shields, inspection plates, and motor lead connection compartments.
c.___ Inspect for proper anchoring coupling, mounting, grounding, and ground
connection. Look for signs of loose or broken bolts, motor housing
cracks, broken motor support brackets, and any evidence of abnormal
rust or chemical action on mechanical and electrical parts.
d.___ Inspect bearings for signs or wear and deterioration. Where journal
bearings are used evaluate bearing condition and clearance.
e.___ The lubrication system of all bearings should be inspected for
satisfactory and normal operation. Change oil and grease. Do not over
lubricate.
f.___ Ground motor windings according to manufacturer's instructions or 30
minutes prior to performing electrical testing, and 30 minutes after
completion of the test.
g.___ All protective devices should be tested in accordance with all
applicable procedures.
2. Synchronous and wound rotor motors:
a.___ Clean and check condition of slip rings and indicators.
b.___ Check condition of all brushes. Look for chipped, cracked, broken, or
otherwise defective brushes. Inspect brush pigtails for damage
resulting from wear and environmental effects.
c.___ Inspect all brushes for satisfactory operation and correct length.
d.___ Check brush box, look for signs of brushes binding due to carbon dust.
e.___ Measure the brush contact pressure of all brushes. Using
manufacturer's instructions, verify the amount of brush pressure to be
applied per square inch.
f.___ Clean and visually inspect resistor bank associated with motor.
3. Shaft Driven Exciters:
a.___ Measure distance from brush box to commutator on all brush boxes.
Refer to manufacturer's specifications for the correct clearance.
b.___ Check spacing between each brush box for equal spacing around
commutator.
c.___ Inspect commutator surface for indication of sparking, threading, drag
grooving, feathering, etc.
d.___ Inspect commutator for chips from broken brushes which may get stuck
between commutator segments.
e.___ Check mida insulation between segments.
f.___ Resurface commutator if necessary, by hand stoning, sandpapering, etc.
g.___ Check the runout of the commutator at several points to verify the
accuracy of the commutator surface. Look for high bars and out of
round conditions.
4. Non Shaft Driven Exciters:
a.___ Remove access covers and vacuum the unit.
b.___ Tighten all connections and look for signs of overheating.
5. Electrical Tests (All Motors):
a.___ Perform dielectric absorption or polarization test on all windings
including exciter windings.
b.___ Conduct dielectric absorption test for a ten minute duration.
Sixty/thirty ration test shall be for a one minute duration.
Polarization test shall be for a ten minute duration. Record test
results. Evaluate test results on motor condition. NOTE: On
synchronous motor with solid state excitation, disconnect exciter
circuits for motor before performing tests.
Tools and Materials:
1. Standard Tool Kit
Plus Insulated pliers and screwdrivers
Wire strippers
Wire crimpers
Voltmeter - Ohmmeter - Milliammeter
Clamp on meter(volt - ohm - amp meter)
Soldering kit
1/8" 25' fish tape
Burnishing tool
2. Megger
3. Vacuum cleaner with attachments
4. Grease gun and fittings
5. Oil can and funnel
6. Cleaning material, rags, sandpiper, small brush, etc. Consult the Material
Safety Data Sheets (MSDS) for hazardous ingredients and proper personal
protective equipment (PPE).
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