97
New generation IZM97, 99 low voltage air circuit breaker instruction manual
MN013010EN February 2020 www.eaton.com.cn
Section 8: Inspection and maintenance
Section 8: Inspection and maintenance
8-1 General
WARNING
Failure to inspect, clean, and maintain circuit breakers
can reduce equipment life or cause the equipment not to
operate properly under fault conditions. This could result
in equipment damage, bodily injury, or even death.
CAUTION
Inspection and maintenance procedures should be carried
out only by personnel familiar with the hazards associated
with working on power circuit breakers. Additionally, they
should become familiar with the specifics associated with
type magnum ds circuit breakers as presented in this
instruction booklet.
IZM9 circuit breakers are “top of the line” equipment. This
means that they are manufactured under a high degree of
quality control, with the best available materials, and with a
high degree of tooling for accuracy and parts interchange-
ability. Design tests and actual installation experience show
them to have durability well beyond minimum standards
requirements. However, because of the variability of applica-
tion conditions and the great dependence placed upon these
circuit breakers for protection and the assurance of service
continuity, inspection and maintenance activities should take
place on a regularly scheduled basis.
Because maintenance of these circuit breakers consists
mainly of keeping them clean, the frequency of scheduled
inspection and maintenance depends to some degree on
the cleanliness of the surroundings. Cleaning and preventive
measures are a part of any good maintenance program.
Plant operating and local conditions can vary to such an
extent that the actual schedule should be tailored to the con-
ditions. When the equipment is subject to a clean and dry
environment, cleaning is not required as frequently as when
the environment is humid with a significant amount of dust
and other foreign matter.
It is recommended that maintenance record sheets be com-
pleted for the equipment. Careful and accurate documenta-
tion of all maintenance activities provides a valuable histori-
cal reference on equipment condition over time.
8-2 General cleaning recommendations
Circuit breaker cleaning activities should be a part of an
overall activity that includes the assembly in which the cir-
cuit breaker is installed. Loose dust and dirt can be removed
from external surfaces using an industrial quality vacuum
cleaner and/or lint-free cloth. Unless otherwise indicated,
never use high-pressure blowing air, because dirt or foreign
objects can be driven into areas, such as the breaker mech-
anism, where additional friction sources could create prob-
lems. Never use a wire brush to clean any part of the circuit
breaker.
8-3 When to inspect
Do not wait for specific scheduled periods to visually inspect
the equipment, if there are earlier opportunities. If possible,
make a visual inspection each time a circuit breaker compart-
ment door is opened, and especially when a circuit break-
er is withdrawn on its compartment extension rails. This
preventive measure could help to avoid future problems.
Industry standards for this type of equipment recommend a
general inspection and lubrication after the number of oper-
ations listed in Table 8-1 of this section. This should also be
conducted at the end of the first six months of service, if
the number of operations has not been reached.
Table 8.1 Inspection frequency
After the first inspection, inspect at least once a year. If
these recommended inspections show no maintenance
requirements, the period may be extended to a more eco-
nomical point. Conversely, if the recommended inspection
shows, for instance, a heavy accumulation of dirt or other
foreign matter that might cause mechanical, insulation, or
other electrical damage, the inspection and maintenance
interval should be decreased.
8-4 What to inspect
What to inspect and to what extent is dictated by the nature
of the maintenance function. Routine inspections require
one type of observation. Inspections following a known
high-level fault require more detailed inspections.
A drawout type circuit breaker should first be withdrawn
from its compartment onto the compartment’s extension
rails. When the inspection is complete, the circuit breaker
can be levered to the TEST position to check the electrical
operations of the circuit breaker. During the levering-out and
levering-in of the circuit breaker, be aware for any signs that
would indicate that this process is not working properly.
During the inspection of fixed type circuit breakers, bus sys-
tems supplying the fixed circuit breakers should be de-ener-
gized for convenience and safety.
For functional testing of the trip unit, refer to the separate
detailed instruction booklet dedicated to the trip unit.
Once the circuit breaker has been cleaned as specified in
Section 8.2, inspect it for any signs of damage, missing or
loose parts, and unusual wear. Be especially alert for foreign
matter that must be removed. On drawout circuit breakers,
inspect the primary disconnect finger clusters for signs of
wear and erosion. Make appropriate corrections to anything
found out of order.
Breaker Frame Size
Interval (Breaker Cycles)
800 A and below
1750
800 A - 3000 A
500
3000 A and above
250
Breaker cycle = one no load open/close operation.
