Rockwell Automation Safety Guidelines for the Application, Installation, and Maintenance of Solid-State Control - Manual (Page 24)

Publication SGI-1.1 - August 2009
24 Section 5 : Preventive Maintenance and Repair Guidelines
7. Enclosures should be inspected for evidence of deterioration.
Accumulated dust and dirt should be removed from the top of the
enclosures before opening doors or removing covers.
8. Certain hazardous materials removed as part of maintenance or repair
procedure (e.g., polychlorinated biphenyls (PCBs) found in some liquid-
filled capacitors) must be disposed of as described in Federal regulations.
C.5.2 Preventive Maintenance
Lithium batteries are frequently used for memory backup in solid-state
equipment due to their excellent shelf life and high energy-to-weight ratio.
Lithium is a highly reactive metal that can cause burns if there is contact
with skin. The batteries are sealed so there is seldom a problem of contact
with lithium as long as reasonable care is exercised when handling them.
They should only be used in their intended application and not subjected
to rough handling. When batteries are replaced in equipment, the batteries
removed should be disposed of in accordance with supplier's instructions.
The Department of Transportation has certain regulations that prohibit
shipment of equipment with batteries installed if the batteries contain 0.5
gram or greater of lithium. The batteries must be removed from
equipment and shipped separately in a container approved by the
Department of Transportation. Additional Department of Transportation
restrictions apply to the shipment of lithium batteries.
NEMA Standards Publication No. ICS 1.3 - 1986, Preventive Maintenance
of Industrial Control and System Equipment, is recommended for
personnel responsible for maintenance of equipment.
5.3 Repair If equipment condition indicates repair or replacement, the manufacturer's
instruction manual should be followed carefully. Diagnostic information
within such a manual should be used to identify the probable source of the
problem, and to formulate a repair plan. The level of field repair
recommended by the manufacturer should be followed.
When solid-state equipment is repaired, it is important that any replacement
part be in accordance with the recommendations of the equipment
manufacturer. Care should be taken to avoid the use of parts which are no
longer compatible with other changes in the equipment. Also, replacement
parts should be inspected for deterioration due to "shelf life" and for signs of
rework or wear which may involve factors critical to safety.
After repair, proper startup procedures should be followed. Special
precautions should be taken to protect personnel from hazards during startup.
Comments: 5.3 — Repair
Follow manufacturer's instructions exactly when replacing power
semiconductors mounted on heatsinks since improper installation may
become the source of further difficulties. Torque semiconductors or bolts
retaining semiconductors to the value specified using a torque wrench.