Arc Flash Hazard Analysis and Mitigation

J. C. Das

• Publisher: Wiley-IEEE Press
• Year: 2020
• ISBN:
  9781119709794
• Edition: 2
• Topic: Technologie et ingénierie
• Subtopic: Ressources d'alimentation

This new edition of the definitive arc flash reference guide, fully updated to align with the IEEE's updated hazard calculations

An arc flash, an electrical breakdown of the resistance of air resulting in an electric arc, can cause substantial damage, fire, injury, or loss of life. Professionals involved in the design, operation, or maintenance of electric power systems require thorough and up-to-date knowledge of arc flash safety and prevention methods. Arc Flash Hazard Analysis and Mitigation is the most comprehensive reference guide available on all aspects of arc flash hazard calculations, protective current technologies, and worker safety in electrical environments. Detailed chapters cover protective relaying, unit protection systems, arc-resistant equipment, arc flash analyses in DC systems, and many more critical topics.

Now in its second edition, this industry-standard resource contains fully revised material throughout, including a new chapter on calculation procedures conforming to the latest IEEE Guide 1584. Updated methodology and equations are complemented by new practical examples and case studies. Expanded topics include risk assessment, electrode configuration, the impact of system grounding, electrical safety in workplaces, and short-circuit currents. Written by a leading authority with more than three decades' experience conducting power system analyses, this invaluable guide:

• Provides the latest methodologies for flash arc hazard analysis as well practical mitigation techniques, fully aligned with the updated IEEE Guide for Performing Arc-Flash Hazard Calculations
• Explores an inclusive range of current technologies and strategies for arc flash mitigation
• Covers calculations of short-circuits, protective relaying, and varied electrical system configurations in industrial power systems
• Addresses differential relays, arc flash sensing relays, protective relaying coordination, current transformer operation and saturation, and more
• Includes review questions and references at the end of each chapter

Part of the market-leading IEEE Series on Power Engineering, the second edition of Arc Flash Hazard Analysis and Mitigation remains essential reading for all electrical engineers and consulting engineers.

1
ARC FLASH HAZARDS AND THEIR ANALYSES

In the past, industrial electrical systems in the United States have been designed considering prevalent standards, that is, ANSI/IEEE, NEC, OSHA, UL, NESC, and the like, and arc flash hazard was not a direct consideration for the electrical system designs. This environment is changing fast, and the industry is heading toward innovations in the electrical systems designs, equipment, and protection to limit the arc flash hazard, as it is detrimental to the worker safety. This opens another chapter of the power system design, analysis, and calculations hitherto not required. There is a spate of technical literature and papers on arc flash hazard, its calculation and mitigation. References [1–8] describe arcing phenomena and arc flash calculations, sometimes commenting on the methodology of arc flash hazard calculations in IEEE Guide 1584 [9] (see Chapter 3).

These issues have become of great importance in the power system planning, designs and protective relay applications. “Safety by Design” is the new frontier (see Chapter 2).

Awareness of the various hazards caused by arc flash has increased significantly over the past decade. Arc flash is a dangerous condition associated with the unexpected release of tremendous amount of energy caused by an electric arc within electrical equipment [10]. This release is in the form of intense light, heat, sound, and blast of arc products that may consist of vaporized components of enclosure material—copper, steel, or aluminum. Intense sound and pressure waves also emanate from the arc flash, which resembles a confined explosion. Arcing occurs when the insulation between the live conductors breaks down, due to aging, surface tracking, treeing phenomena, and due to human error when maintaining electrical equipment in the energized state. The insulation systems are not perfectly homogeneous and voids form due to thermal cycling. In nonself restoring insulations, treeing phenomena starts with a discharge in a cavity, which enlarges over a period of time, and the discharge patterns resemble tree branches, hence the name “treeing” (Figure 1.1). As the treeing progresses, discharge activity increases, and, ultimately the insulation resistance may be sufficiently weakened and breakdown occurs under electrical stress. Treeing phenomena is of particular importance in XLPE (cross-linked polyethylene) and nonself restoring insulations. Surface tracking occurs due to abrasion, irregularities, contamination, and moisture, which may lead to an arc formation between the line and ground. An example will be a contaminated insulator under humid conditions. Though online monitoring and partial discharge measurements are being applied as diagnostic tools, the randomness associated with a fault and insulation breakdown are well recognized, and a breakdown can occur at any time, jeopardizing the s...