Arc flash hazard
Das, J.C. AMEC, Inc., Tucker, Georgia.
- Types of electrical hazard
- Basic concepts
- Labeling requirements
- Arc flash analysis
- Links to Primary Literature
- Additional Readings
The arc flash hazard is a dangerous condition associated with the unexpected release of a tremendous amount of energy caused by an electrical arc within electrical equipment. This release of energy is in the form of intense light, heat, and blast of arc products, which may consist of vaporized components of enclosure material (copper, steel, and aluminum). Intense high sound and pressure waves also emanate from the arc flash, which resembles a confined explosion. Arcing occurs when the insulation between two live conductors breaks down, due to aging, tracking, tree formation, and human error during maintenance. Insulation systems are not perfectly homogeneous. Thermal aging, vibrations, impact damage, fractures, and abraded areas give rise to further development of cavities and partial discharges occur (partial discharge, PD, is a localized electrical discharge that partially bridges the insulation between conductors and which may or may not occur adjacent to conductors.) These discharge patterns, as they grow, resemble a tree and thus the term “treeing.” Ultimately the insulation resistance is much lowered and a breakdown occurs. Tracking occurs due to surface contamination. This provides a relatively low impedance path for the electrical arc to strike, say, between the line to ground. An example will be a contaminated insulator under high humidity conditions. Arc temperatures are of the order of 35,000°F (20,000°C), approximately four times the temperature on the surface of the Sun.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Its dedicated editorial team is led by Sagan Award winner John Rennie. Contributors include more than 9000 highly qualified scientists and 42 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 17,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information