3 . 2
Maintenance
Both long and short term maintenance o f a l l electrical
equipment is essential for reliability and safety. Mainte
nance programs must be tuned to the specific application,
well planned and carried out consistent with both industry
experience and manufacturer's recommendations. Local
environment must always be considered in such pro
g rams, including such variables as ambient temperatures,
extreme moisture, number of o perations, corrosive atmo
sphere or major insect problems and any other unusual or
abusive condition of the application.
One of the critical service activities, sometimes neglected,
involves the calibration of various control d evices. These
monitor conditions in the primary and secondary c ircuits,
sometimes initiating emergency corrective action such as
opening or closing circuit breakers. I n view of the vital role
of these devices, it is important that a periodic test
p rogram be followed. As was outlined above, it is recog
n ized that the interval between periodic checks will vary
depending u pon environment, the type of device and the
user's experience. It is the General Electric recommenda
tion that, until the user has accumulated enough experience
to select a test interval better suited to h is individual
requirements, all significant c alibrations be checked at an
interval of one to two years.
To accom plish this, sorne items, such as "EC" direct
operating trip systems for low voltage breakers, must be
tested with primary current injection. Others can be
adequately tested using test sets. Specific calibration
instructions on particular devices typ ically are provided
by supplied instruction books.
Instruction books supplied by manufacturers address
com ponents that would normally require service or main
tenance during the useful life of the equi pment. However,
they can not include every possible part that could require
attention, particularly over a very long service period or
under adverse environments. M aintenance personnel
must be alert to deterioration of any part of the supplied
switchgear, taking actions, as necessary to restore it to
serviceable status.
I ndustry publications of recommended maintenance prac
tices such as ANSI/NFPA 708, E lectrical Equipment
Maintenance, should be carefully studied and applied in
each user's formation of plan ned maintenance.
Some users may require additional assistance from Gen
eral E lectric in t h e p la n n i ng a n d performance of
maintenance. The General Electric Company can be
contracted to either undertake maintenance or to p rovide
technical assistance such as the latest publications.
The performance and safety of this equipment may be
compromised by the modification of supplied parts or their
replacement by non identical substitutes. All such design
changes must be qualified to ANSI/IEEE Standard C37.59.
The user should methodically keep written maintenance
records as an aid in future service planning and equipment
reliability improvement. Unusual experiences should be
promptly communicated to the General Electric Company.
1 0A
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