Search

Since the arc-fault circuit interrupter (AFCI) was commercially introduced in 1998, questions have arisen about how it detects arcs, whether it detects series and parallel arcs, and what types of AFCIs are available. Types other than the original branch/feeder AFCI are emerging. This paper is intended to provide an update regarding answers to those questions, following an earlier paper that introduced the basic functioning of the AFCI. Index Terms--Arc fault, arc-fault circuit interrupter (AFCI), arc-fault detection.

A series of previous papers has provided information regarding the arc flash hazard and methods of calculating its potential impact on persons working on or near the equipment. This paper extends that base of information by focusing on the arcing current level and duration in low-voltage circuits protected by circuit breakers (CBs). It describes a method of calculating incident energy and the flash protection boundary due to arcing occurrences in equipment protected by CBs. This method provides convenient procedures for determining these values for generic situations in which some details of the CB are not known. Further, it provides a process for determining these values in typical feeder and branch circuit applications involving common transformers and cable sizes and lengths. The values are needed to determine safe work practices and appropriate Personal Protective Equipment to comply with NFPA 70E, Standard for Electrical Safety Requirements for Employee Workplaces. Index Terms--Arc flash, circuit breaker (CB), flash protection boundary, incident energy.

Series-rated circuit breakers are commonplace, but not always well understood. This paper provides basic information on how a series rating is tested and relates that information to the interaction of the overcurrent protective devices involved. The paper also explores the question of whether calculations can be used to determine the series rating of an untested combination. Index Terms--Dynamic impedance, molded-case circuit breaker (MCCB), overcurrent protection, series rating.

The purpose of this paper is to examine the application of low-voltage circuit breakers to control the energy released during an arc-flash occurrence. It contrasts arc-flash incident-energy values obtained by calculation with values obtained by direct testing. It examines values at low fault current levels where long duration events may be expected. It also reviews the protection afforded by current-limiting circuit breakers. This paper concludes with an overall discussion of circuit breaker applications for arc-flash energy reduction. [ABSTRACT FROM AUTHOR]

Deals with a study which clarified the single-post test requirements of molded-case circuit breakers. Voltage convention; Individual-pole circuit breaker tests; Description of several electrical systems; Discussion on the individual-pole fault conditions under a variety of systems; Conclusions.

Presents guidelines for system application within the established system of the product standards and safety codes. Product certification standard testing; Applicable standards and codes; System evaluation philosophy; Circuit breaker testing related to function; Impedance analysis.

Presents information on a study which focused on the emergence of arc-fault circuit interrupter products. Types of arc-faults; Arc characteristics; Contrast with ground-fault circuit interrupter protection.

Addresses the application of instantaneous-trip molded-case circuit breakers (MCCB) in combination motor starters. Description of a combination starter; Functions of combination starters; Discussion on MCCB; Testing of the circuit breakers.

Confirms the existence of low-voltage motor short-circuit contribution by test. Literature background; Typical installations; Application guidelines; Motor characteristics; Circuit description.