Safe Distances From a High-Energy Capacitor Bank for Ear and Lung Protection

Hammer, Charles R; Pearson, Richard; Porschet, Donald

doi:10.21236/ada606360

Cited by 4 publications

(2 citation statements)

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“…Acoustic pressures from facility type arcs was first highlighted in 1979 [32] and discussed in several subsequent publications [33][34][35][36]. Acoustic pressures in fast rise time arcs results in super sonic wave fronts and has been studied related to lightning and capacitor bank discharges, which occur in the order of microseconds [37][38][39][40]. 4) Shrapnel results from the high currents that melt electrode materials, and acoustic and magnetic forces that dismantle and propel parts, especially metal parts [36].…”

Section: Electrical Energy Conversionmentioning

confidence: 99%

“…An approximate estimate for sufficient energy to create sparks, reaching the eyes, would be 100 J; for sufficient energy to create an arc flash of 1 cm, would be 20 J; for sufficient energy to create an arc flash of 10 cm, would be 2 kJ; for sufficient energy to create an arc flash of 100 cm, would be 200 kJ; and, sufficient energy to injure the ears from a fast rise time capacitor discharge, would be 20 J (assumes 1 % probability of injury, 50 % conversion to acoustic energy, and 45 cm working distance [39]. Acoustic energy injury thresholds for continuous arcs (e.g., an arc welder) are likely much higher (5 kJ per second) and for a slow impulse arc from a 60 Hz source, perhaps 20 kJ.…”

Section: ) Energy As a Thresholdmentioning

confidence: 99%

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A complete electrical arc hazard classification system and its application

Gordon

Cartelli

Graham

2015

2015 IEEE IAS Electrical Safety Workshop

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The Standard for Electrical Safety in the Workplace, NFPA 70E, and relevant OSHA electrical safety standards evolved in the US, over the past 40 years, to address the hazards of 60-Hz power that are faced primarily by electricians, linemen, and others performing facility and utility work. This leaves a substantial gap in the management of other types of electrical hazards including battery banks, DC power systems, capacitor banks, and solar power systems. Although many of these systems are fed by 50/60-Hz alternating current (ac) energy, we find substantial use of direct current (dc) electrical energy, and the use of capacitors, inductors, batteries, solar, and radiofrequency (RF) power. The electrical hazards of these forms of electricity and their systems are different than for 50/60 Hz ac power.At this workshop in 2009 we presented a comprehensive approach to classifying the electrical shock hazards of all types of electricity, including various waveforms and various types of sources of electrical energy. That paper introduced a new comprehensive electrical shock hazard classification system that used a combination of voltage, shock current available, fault current available, power, energy, and waveform to classify all forms of electrical hazards with a focus on the shock hazard.

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