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 3.5.8 Operating Condition of Breaker.
3.5.8.1 Condition of Circuit Breaker During Interrupting Operation. An oil circuit breaker
should perform at, or within, its interrupting rating without emitting flame and without releasing
oil (except for minimum quantities through vent openings). Oilless circuit breakers (including
compressed-air circuit breakers and magnetic air circuit breakers) should perform, at or within,
their respective interrupting ratings without emitting injurious flame. The generally accepted
duty cycle is two close-open operations at 15 second intervals.
3.5.8.2 Condition of Circuit Breaker Following Interrupting Performance. After
completing an interruption, the components of the circuit breaker should be in essentially the
same mechanical condition as prior to the interruption.
3.6 AUTOMATIC CIRCUIT RECLOSERS. An automatic circuit recloser is a self-contained
protective device that automatically interrupts and recloses alternating current circuits with
predetermined sequences of opening and reclosing, followed by resetting or lockout. Unlike fuse
links, which interrupt either temporary or permanent faults indiscriminately, reclosers give
temporary faults repeated chances to clear themselves or to be cleared by a subordinate protective
device. If the fault is not cleared, the recloser recognizes it as permanent and operates to lock
out.
3.6.1 Purpose. Reclosers are installed to maintain power to distribution loads with a
minimum of outages. Reclosers instantly clear and reclose a circuit subjected to: a temporary
fault due to lightning, trees, or similar causes; or by removing a permanently faulted circuit from
the system.
3.6.2 Application. Automatic circuit reclosers are used in distribution substations and on
branch feeders that are vulnerable to temporary short circuits (such as bare overhead conductor
systems) to protect and switch feeder circuits. Their proper application requires a study of the
load characteristics of both the protecting and the protected equipment. This includes the
medium-voltage fuses or other protection in the supply to a substation; circuit breakers or
reclosers at the distribution voltage supplying the feeders originating at the substation; various
line reclosers, sectionalizers or fuses; and the conductors of the system.
3.6.3 Ratings. Automatic circuit reclosers are rated in terms of voltage, continuous current,
minimum trip current and interrupting current. In operating a recloser, the limitations imposed
by a given recloser rating must not be exceeded in any respect; otherwise, excessive maintenance
or unsatisfactory operation may be experienced.
3.6.3.1 Voltage Rating. Nominal voltage specifies the nominal system voltage at which
the recloser can be applied. Maximum design voltage indicates the highest voltage at which the
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