FA112978
31/01/2018
Issue:
What is a current-limiting circuit breaker?
Product Line:
Molded Case Breaker, Powerpact
Environment:
Products sold in North America
Cause:
Need to understand the definition of a current limiting breaker.
Resolution:
A current-limiting circuit breaker is one that has been certified by UL to limit the let-thru I^2t (I squared t) during a fault to not more than the I^2t available during a half-cycle of prospective symmetrical short-circuit current. Maximum let-through I^2t and peak current levels are published on curves available with the trip curves for the current-limiting breakers.
The Schneider Electric current limiting breaker now available in North America are the Powerpact HJ/HL/HR, JJ/JL/JR, and LJ/LL/LR frame circuit breakers.
See Let-Through Current Curves in https://www.schneider-electric.us/en/download/document/0611CT1001 on page 211.
Other recently obsolescent current limiting breakers also included FI, KI, LI, and LXI.