# IEEE C37.13-2008 pdf free

**IEEE C37.13**-2008 pdf free.IEEE Standard for Low-Voltage AC Power Circuit Breakers Used in Enclosures.

For an unfused circuit breaker, the rated short-time current is the designated limit of available (prospective) current at which it shall be required to perform its short-time current duty cycle (two periods of 0.5 s current flow, separated by a 15 s interval of zero current) at rated maximum voltage under the prescribed test conditions. This current is expressed as the mis symmetrical value of current measured from the available current wave envelope at a time one-half cycle after short-circuit initiation.

tJnfuscd circuit breakers shall be tested to and be capablc of performing the short-time current duty cycle with all degrees of current asymmetry produced by three-phase or single-phase circuits having a shortcircuit power factor of 15% lagging or less (XR ratio of 6.6 or greater). Short-time current ratings are listed in ANSI C37.l6.

5.5.2 Fused circuit breakers

Fused circuit breakers do not have a rated short-time current rating.

NOTE- —The nameplate of a fused circuit breaker does no include a short-time current rating. However, the circuit breaker clement of the fused circuit breaker assembly may have a short-time capability. The manufacturer should be consulted for details as needed,

5.6 Rated short-circuit current

5.6.1 General

The circuit breaker rated short-circuit current capabilities are demonstrated by compliance with the applicable test requirements in ANSI C37.50.

5.6.2 Circuit breaker (50 Hz or 60 Hz)

A circuit breaker with rated power frequency of 50 lIz shall be required to perform its short-circuit current duty cycle at rated power frequency of 50 Hz.

A circuit breaker with rated power frequency of 60 Hz shall be required to perform its short-circuit current duty cycle at rated power frequency of 60 Hz.

A circuit breaker with rated power frequency of 5OHz60 Hz shall be required to perform its short-circuit current duty cycle as follows:

a) When the published tolerance bands of the time-current curves of the circuit breaker direct-acting trip system (see ANSI C37. 17) at 50 Hz do not fall entirely within the published tolerance hands of the lime-current CUrVeS at 60 1 Iz. the short-circuit current tests shall be conducted at each rated power frequency.IEEE C37.13 pdf free download.