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
December 2-3, 2014
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
December 2-3, 2014
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)
December 2-3, 2014
Arc flash hazards
December 2-3, 2014
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.
December 2-3, 2014
Different arc protection solutions • Passive protection
December 2-3, 2014
• Active protection
Passive protection, PPE suit requirements
December 2-3, 2014
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
December 2-3, 2014
IEEE 1584™ final step calculation of incident energy:
NFPA 70E-2004 calculation of incident energy:
Incident energy example
December 2-3, 2014
Without active Arc protection
December 2-3, 2014
With active Arc protection
December 2-3, 2014
Segments that need Arc protection
December 2-3, 2014
Q&A - session
December 2-3, 2014