51
DISCONNECT SWITCH PREVENTIVE MAINTENANCE
Adapted from Power O&M Bulletin No. 19 -
Maintenance Schedules and Records - October 1965,
Section 11 and NFPA 70B, Appendix H
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 30, "Switches, Disconnect," in the body of this FIST volume.
maintenance annually (indicated by *) or when the equipment becomes
available during an outage. For other maintenance requirements, see
section 30, "Switches, Disconnect," in the body of this FIST volume.
Inspection
Semi-Annual Observe components visible through inspection windows: switch
contacts, auxiliary devices, wiring, terminal blocks, fuse clips and fuses, insulators and
insulating materials, space heater operation, cable terminations, adequate grounding,
cleanliness, evidence of water leaks, and overheating of parts. Observe stress cones
and leakage sections for cleanliness and tracking. Record loads if equipped with
meters.
contacts, auxiliary devices, wiring, terminal blocks, fuse clips and fuses, insulators and
insulating materials, space heater operation, cable terminations, adequate grounding,
cleanliness, evidence of water leaks, and overheating of parts. Observe stress cones
and leakage sections for cleanliness and tracking. Record loads if equipped with
meters.
Weekly Note whether multiple-shot reclosing fuse has operated. Replace as needed.
Check fuse latching and tripping mechanism for proper operation.
Check fuse latching and tripping mechanism for proper operation.
Major Maintenance or Overhaul
Depending on ambient, 3 to 6 years.
Major Maintenance or Overhaul
Maintenance to Perform
Structure and enclosure
Repair rust spots and paint.
Base and mounting
Check for loose bolts and insecure or inadequate supporting
structure.
structure.
Ventilating louvers and air filters
Clean and replace as needed.
Buses, splices, and bolts
Check bolts for manufacturer's recommended torque.
Insulators
Check for chipped or broken porcelain, excessive dirt film,
and tracking; clean as necessary; replace broken insulators;
tighten base and cap bolts.
and tracking; clean as necessary; replace broken insulators;
tighten base and cap bolts.
Space Heaters
Verify operation or operate continuously to overcome
thermostat malfunction.
thermostat malfunction.
Main switch blades and contacts
See that blades are properly seated in the contacts; operate
the switch several times and see that blades are properly
aligned to engage contacts; clean contact surfaces if
corroded; lubricate; tighten bolts and screws.
the switch several times and see that blades are properly
aligned to engage contacts; clean contact surfaces if
corroded; lubricate; tighten bolts and screws.