Introduction and Maintenance Intervals
Periodic inspections and maintenance are essential to
obtain safe and reliable operation of the GMI circuit
breaker.
When GMI circuit breakers (manufactured beginning
January, 1992) are operated under “Usual Service Condi-
tions,” maintenance and lubrication is recommended at
five year (one year if manufactured before January, 1992)
intervals or at the number of operations indicated in Table
2. “Usual” and “Unusual” service conditions for Medium
Voltage Metal-Clad Switchgear are defined in ANSI
C37.20.2, sections 4 and 8.1. Generally, “usual service
conditions” are defined as an environment in which the
equipment is not exposed to excessive dust, acid fumes,
damaging chemicals, salt air, rapid or frequent changes in
temperature, vibration, high humidity, and extremes of
temperature.
The definition of “usual service conditions” is subject to a
variety of interpretations. Because of this, you are best
served by adjusting maintenance and lubrication intervals
based on your experience with the equipment in the actual
service environment.
Regardless of the length of the maintenance and lubrica-
tion interval, Siemens recommends that circuit breakers
should be inspected and exercised annually.
For the safety of maintenance personnel as well as others
who might be exposed to hazards associated with mainte-
nance activities, the safety related work practices of NFPA
70E, parts II and III, should always be followed when
working on electrical equipment. Maintenance personnel
should be trained in the safety practices, procedures and
requirements that pertain to their respective job assign-
ments. This manual should be reviewed and retained in a
location readily accessible for reference during
maintenance of this equipment.
The user must establish a periodic maintenance program
to ensure trouble-free and safe operation. The frequency
of inspection, periodic cleaning, and preventive mainte-
24
Maintenance
nance schedule will depend upon the operation
conditions. NFPA Publication 70B, “Electrical Equipment
Maintenance” may be used as a guide to establish such a
program. A preventive maintenance program is not
intended to cover reconditioning or major repair, but
should be designed to reveal, if possible, the need for such
actions in time to prevent malfunctions during operation.
Recommended Hand Tools
Type GMI circuit breakers use both standard American and
metric fasteners. Metric fasteners are used for the GMI
vacuum interrupters. American fasteners are used in all
other locations. This list of hand tools describes those
normally used in disassembly and re-assembly procedures.
Metric (Vacuum Interrupter Only)
• Deep Sockets: 19 and 24 mm
• Torque Wrench: 0-150 Nm (0-100 ft-lbs.)
• Allen Wrenches: 8 and 10mm
American (All Other Breaker Locations)
• Socket and Open-End Wrenches: 5/16, 3/8, 7/16,
1/2, 9/16 and 3/4 in.
• Hex Keys: 3/16 and 1/4 in.
• Screwdrivers: 0.032 x 1/4 in. wide and
0.55 x 7/16 in. wide
• Pliers
• Light Hammer
• Dental Mirror
Table 1 – Maintenance Tasks
• Checks of the Primary Power Path
• Checks of the Interrupter Operator Mechanism
• Electrical Control Checks
• High Potential Test
• Inspection and Cleaning of Breaker Insulation
• Functional Tests
Hazardous voltages and high-speed
mechanical parts.
Will cause death, severe personal injury, or
property damage.
Read instruction manuals, observe safety
instructions and limit use to qualified
personnel.
DANGER
WARNING
Failure to maintain the equipment could result in death,
serious injury or product failure, and can prevent successful
functioning of connected apparatus.
The instructions contained herein should be carefully reviewed,
understood, and followed.
The maintenance tasks in Table 1 must be performed regularly.
