Circuit breakers are
designed primarily to per
form the function of circuit
interruption under short
circuit conditions. Neverthe
less, modern circuit breaker
mechanisms are capable of
many operations under full
load operation and in-rush
conditions such as encoun
tered in motor starting appli-
Ta!Jie 55. '
Circuit Breaker
Frame Size
(Amperes)
225
800
1 600
2000
3200
4000
(A)
Servicing consists of
adjusting, cleaning, lubricat-
ing, tightening, etc., as rec-
om mended by the manu-
facturer. When current is
interrupted, dressing of con-
tacts may be required as
well. The operations listed
are on the basis of servicing
at intervals of six months or
less.
(B)
When closing and open-
ing no-load.
(C) With rated control volt-
age applied.
(D)
Frequency of operation
not to exceed 20 in ten min-
utes or 30 in an hour. Rectifi-
cations. Industry standards
have been established tor
the minimum performance
which is indicated in the
table below. With adequate
maintenance, GE breakers
can be expected to exceed
the standards.
Power operated circuit
breakers, when operating
under usual service condi
tions, shall be capable of
operating the number of
times specified in the follow
ing table. The operating
conditions and the permissi
ble effect of such operations
upon the breaker are given
in the following lettered para
graphs. For each column,
all paragraphs listed in the
Number of
Number of
Operations
Operations
Number of
Related Continuous
No-Load
Operations
Current
Closing and
Between
Switching
Opening
Servicing
(A) (C) (D) (E)
(A) (B) (C) (D)
(F)
(G)
(H)
and
(J)
(E) (F)
and (G)
2500
4000
1 0000
1750
2800
9700
500
800
3200
500
800
3200
250
400
1 1 00
250
400
1 1 00
ers or other auxiliary devices tional part replacement and
may further limit the fre-
general servicing may be
quency of operation.
necessary.
(E)
Servicing at no greater
(H)
When closing and open-
intervals than shown in
ing current up to the contin-
second column above.
uous current rating of the
circuit breaker at voltages up
(F)
No functional parts
to the rated maximum volt-
should have been replaced
age and at 85% of the power
during the listed operations.
factor or higher.
(G)
The circuit breaker
{I)
When closing currents
should be in a condition to
up to 600% and opening
carry its rated continuous
currents up to 100% (80%
current at rated maximum
power factor or higher) of the
voltage and perform at least
continuous current rating of
one opening operation at
the circuit breaker at volt-
rated short-circuit current.
ages up to the rated maxi-
After completion of this
mum voltage.
series of operations, func-
When closing currents
column heading must
be given consideration.
This standard applies to all
parts of a circuit breaker that
function during normal oper
ation. It does not apply to
other parts, such as over
current tripping devices, that
function only during infre
quent abnormal circuit
conditions.
Number of
Operations
In-Rush
Current
Switching
(C) (D) (E)
(F)
(G) (I) and
(J)
2000
1400
400
400
-
-
up to 600% and opening
currents up to 600% (50%
power factor or less) of the
continuous current rating of
the circuit breaker at volt-
ages up to rated maximum
voltage, the number of oper-
ations shown shall be re-
duced to 1 0% of the number
listed.
(J)
If a fault operation occurs
before the completion of the
l isted operations, servicing
is recommended and possi-
ble functional part replace-
ments may be necessary,
depending on previous
accumulated duty, fault
magnitude, and expected
future operations.
55
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