GENERATOR AND LARGE MOTOR PREVENTIVE MAINTENANCE
Adapted from Power O&M Bulletin No. 19 -
Maintenance Schedules and Records - October 1965, Section 8.
NOTE: Unless the maintenance interval is specified, conduct preventive
maintenance annually (indicated by *) or when the equipment becomes
available during an outage. For other maintenance requirements, see section
19, "Generator and Large Motors," in the body
of this FIST volume.
Foundation, Base, or Support
* Check concrete foundation for cracks. Check base or support for broken, loose, or
weakened parts. Check and tighten anchor bolts. Check sound-absorbing base for
* Check for cracks and loose or broken parts. Clean and repaint as necessary. Check
frame ground connection.
Laminations and Pole Pieces
* Check for loose laminations and tighten clamping bolts. If laminations vibrate and
cannot be stopped by tightening clamping bolts, force some quick-drying varnish or
shellac between the loose laminations while the machine is out of service. Check for
damaged laminations at airgap due to rubbing or objects caught in airgap. Check
and tighten field pole piece clamping bolts. (Refer to manufacturer's instructions or
contact the Hydroelectric Research and Technical Services Group at 303-445-2300
for proper torque values.)
Armature or Rotor
* Check squirrel-cage rotor bars or amortisseur windings for loose or broken bars or
end connections. Check field circuit connections and tighten if necessary. Check
voltage drop across each pole by applying alternating current at the collector rings.
This method will show a turn-to-turn short better than using direct current. Check
pole keys for tightness. Rebalance armature or rotor if vibration is objectionable.
(See FIST Volume 2-2, Field Balancing of Large Rotating Machinery.)
* Check overall rotor resistance or impedance.