90 Rockwell Automation Publication 750-IN119A-EN-P - April 2022
Chapter 6 Service and Maintenance
Operating Mechanisms - Check for proper function and freedom from
sticking or binding. Replace any broken, deformed, or badly worn parts or
assemblies according to individual product renewal-parts lists. Check for and
re-tighten securely any loose fasteners. Lubricate if specified in individual
product instructions. Note: Allen-Bradley® magnetic starters, contactors, and
relays are designed to operate without lubrication. Do not lubricate these
Allen-Bradley devices because oil or grease on the pole faces (mated surfaces)
of the operating magnet can cause the device to stick in the “ON” mode. Some
parts of other devices are factory lubricated – if lubrication during use or
maintenance of these devices is needed, it is specified in their individual
instructions. If in doubt, consult your nearest Rockwell Automation sales
office for information.
Contacts - Check contacts for excessive wear and dirt accumulation. Wipe
contacts with a soft cloth, if necessary, to remove dirt. Discoloration and slight
pitting does not harm contacts. Do not file contacts - this action shortens the
life of the contact. Do not use contact spray cleaners because residue on
magnet pole faces or in operating mechanisms can cause sticking, and on
contacts can interfere with electrical continuity. Replace contacts only after
the silver has become badly worn. Always replace contacts in complete sets to
avoid misalignment and uneven contact pressure.
Terminals - Loose connections in power circuits can cause overheating that
can lead to equipment malfunction or failure. Loose connections in control
circuits can cause control malfunctions. Loose bond or ground connections
can increase hazards of electrical shock and contribute to electromagnetic
interference (EMI). Check the tightness of all terminals and bus bar
connections and torque any loose connections properly. Infrared technology
can be used to check for hot (high resistance/loose) connections during
periodic maintenance. Replace any parts or wiring that is damaged by
overheating, and any broken wires or bond straps.
Coils - If a coil is overheated (contains cracked, melted, or burned insulation),
it must be replaced. In that event, check for and correct overvoltage or
undervoltage conditions, which can cause coil failure. Be sure to clean any
residues of melted coil insulation from other parts of the device or replace such
parts.
Pilot Lights - Replace any burned out lamps or damaged lenses. Photoelectric
Switches-The lenses of photoelectric switches require periodic cleaning with a
soft dry cloth. Reflective devices that are used with photoelectric switches also
require periodic cleaning. Do not use solvents or detergents on the lenses or
reflectors. Replace any damaged lenses and reflectors.
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