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Description / Abstract:
This standard covers the following types and preferred ratings
for enclosed low-voltage ac power circuit breakers:
a) Stationary or drawout type of two-, three-, or four-pole
construction with one or more rated maximum voltages of 1058 V, 730
V, 635 V (600 V for units incorporating fuses), 508 V, or 254 V for
application on systems having nominal voltages of 1000 V, 690 V,
600 V, 480 V, or 240 V respectively
b) Unfused or fused type
c) Manually operated or power operated, with or without a trip
system
d) Fused drawout assemblies consisting of current-limiting fuses
in a drawout assembly intended to be connected in series with a
low-voltage ac power circuit breaker to form a nonintegrally fused
circuit breaker
In this standard, the term circuit breaker shall mean enclosed
low-voltage ac power circuit breaker, either fused or unfused. The
term unfused circuit breaker shall mean a circuit breaker without
either integrally or nonintegrally mounted fuses, and the term
fused circuit breaker shall mean a circuit breaker incorporating
current-limiting fuses, whether integrally mounted or nonintegrally
mounted.
Purpose
This standard
a) Establishes minimal functional requirements
b) Establishes preferred rating structure
c) Provides preferred ratings