Quantcast Figure 5-8. Maintenance for typical low voltage switchgear with air circuit breakers

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TM 5-685/NAVFAC MO-912
(a) Use recognized industrial practices as the
several times during the period, preferably under
general guide for servicing and refer to manufactur-
load. If the breaker is operated by a relay or a
er's literature.
switch, it should be so operated at this time.
(b) The user should refer to manufacturer's
( e ) Service for molded-case circuit breakers
literature for specific information on individual cir-
consists of the following procedures. Inspect connec-
cuit breakers.
tions for signs of arcing or overheating. Replace
(c) General service information for circuit
faulty connectors and tighten all connections. Clean
breakers includes the following safety require-
the connecting surfaces. Perform overload tripping
ments. Do not work on an energized breaker. Do not
tests. Verify automatic opening of breaker. Verify
work on any part of a breaker with test couplers
that the magnetic tripping feature is operating. Per-
engaged. Test couplers connect the breaker to the
form circuit breaker overload tripping tests. Proper
control circuit during testing. Spring-charged
action of the breaker tripping components is veri-
breaker mechanisms shall be serviced only by per-
fied by selecting a percentage of breaker current
sonnel experienced in releasing the spring load in a
rating (such as 300%) for testing. This overload is
controlled manner. Make operational tests and
applied separately to each pole of the breaker to
checks on a breaker after maintenance, before it is
determine how it will affect automatic opening of
returned to service. Do not work on a spring-
the breaker. Refer to manufacturer's test informa-
charged circuit breaker when it is in the charged
tion. Turn the breaker on and off several times to
position.
verify satisfactory mechanical operation.
(d) Switchge ar needs exercise. If the circuit
( f ) Service for air circuit breakers consists of
breaker remains idle, either open or closed, for six
the following procedure (see fig 5-8). Install the
months or more, it should be opened and closed
safety pin to restrain the closing spring force. With
CONNECTED
ALL POWER
(PR I MA R Y
CONTROL)
CONTROL POWER
STILL CONNECTED
--DISCONNECTED
ALL POWER DISCON-
NECTED
WITHDRAWN
BREAKER WITHDRAWN
READY FOR REMOVAL
Figure 5-8. Maintenance for typical low voltage switchgear with air circuit breakers.
5-8





 


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