Arc Flash Hazards and Arc Mitigation Solutions
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Transcript of Arc Flash Hazards and Arc Mitigation Solutions
Arc Flash Hazards and Arc Mitigation Solutions
Shlomy Allalouf, Shallan Garrett, and Karin Lundbom
Arc Flash Hazards and Arc Mitigation Solutions
Shlomy Allalouf, Shallan Garrett and Karin Lundbom, ABB
Content
• Introduction to Arc flash
• Arc flash standards
• Arc protection and arc mitigation solutions
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Electric Arc phenomenon
• The electric arc is a phenomenon that takes place as a consequence of a discharge.
• This occurs when the voltage between two points exceeds the insulating strength limit of the interposed gas
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Dangers associated with Arc flashes
• Flying debris • Copper expands by a factor of 67,000:1 when turning
from solid to vapor • Molten metal and shrapnel travel as fast as
1600km/hour • Pressure
• The sound of an arc blast can easily surpass 160dB (OSHA limit is 115dB for max 15 minutes, NIOSH limit is 112dB for max 56 seconds)
• Arc blasts can and have caused death at distances above 10ft (3m)
• Extreme heat • Temperature of arc an blast can reach over 21,000
oC
(surface of the sun is roughly 5500 oC)
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Arc flash hazards
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Arc Flash Regulating Codes and Industry Standards • IEEE Standard 1584 Guide for Performing Arc Flash Hazard
Calculations • NFPA 70E Standard for Electrical Safety Requirements for
Employee Workplaces • OSHA 29 Code of Federal Regulations (CFR) Part 1910
Subpart S • NFPA 70 National Electrical Code (NEC) • C37.20.7 IEEE Guide for Testing Medium-Voltage Metal-
Enclosed Switchgear for Internal Arcing Faults • IEC 61641 This technical report applies to enclosed low-
voltage switchgear and controlgear assemblies manufactured according to IEC 60439-1.
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Different arc protection solutions • Passive protection
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• Active protection
Passive protection, PPE suit requirements
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0 1 2 3 4 <1.2 cal/cm2 1.2-4 cal/cm2 4-8 cal/cm2 8-25 cal/cm2 25-40 cal/cm2
Time is crucial for active protection
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IEEE 1584™ final step calculation of incident energy:
NFPA 70E-2004 calculation of incident energy:
Incident energy example
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Without active Arc protection
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With active Arc protection
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Segments that need Arc protection
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Q&A - session
December 2-3, 2014