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 TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
Figure 5-8. Solid-state starter
Small breakers are fairly low in cost, and labor costs
the operating environment or critical load being
do not justify repair. For larger sizes, replacement
served.
(1) Routine field testing. The following consti-
parts will include such items as handles, arc chutes,
tutes a guide for the types of tests which might be
and trip units. Trip units are sealed to prevent tam-
performed during routine maintenance of molded-
pering. Where a trip unit itself is found to be faulty,
case breakers. The tests recommended are based on
it should be replaced as a unit, rather than re-
paired. Some users maintain a regular program of
proven standard maintenance practices and are
aimed at assuring that the breaker is functionally
calibration checks (verification testing) to verify the
trip point. These tests can be performed on the
operable. All tests are to be made only on breakers
plant premises. In conducting such tests, care
and equipment that are de-energized. Extreme at-
should be taken to follow the manufacturer's spe-
mospheres and conditions may reduce the dielectric
cific instructions. Where conditions are not closely
strength of any insulating material including those
controlled, misleading results can be obtained. Test
of which molded case breakers are made. Therefore,
limits provided by the manufacturer must be ob-
the first routine check recommended is an insula-
served. But, generally, it is advisable to operate and
tion resistance test (para 14-2). The voltage recom-
inspect the circuit breaker when maintenance of
mended for this test should be at least 50 percent
other components of the motor controls or panel
greater than the breaker rating. However, a mini-
board is being performed. Recommended proce-
mum of 500 volts is permissible. Tests should be
dures are routine testing and verification testing.
made between phases of opposite poles as well as
These two types of testing are optional and are
from current-carrying parts of the circuit breaker to
implemented at selected locations depending upon
ground. Also, a test should be made between the
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