The New IEEE-1584 Guide for Performing Arc-Flash

<1.0 kV

0.7-106kA at 230

13.8 kV

5.4-40.4 kA at 18

14.3kV

270 at # ~3.5million donated for these tests # IEEE 1584- 2018 Highlights Key Changes New arcing fault (Iarc) equations • New incident energy (IE) equations Electrode Configuration-Very Significant! • Enclosure size factor (CF) • New guidance for equipment =<240V • Arc: Plasma cloud formed in a gap between two electrodes with sufficient potential difference # IEEE 1584- 2018 Highlights Definitions Arc flash: An electric arc event with thermal energy dissipated as radiant, convective, and conductive heat. Fault current: A current that flows from one conductor to ground or to another conductor due to an abnormal connection between two conductors. Bolted fault: A short-circuit condition that assumes zero impedance exists at the point of the fault. • Arcing fault current (Arc current): A fault current flowing through an electric arc plasma. Incident Energy (IE in cal/cm2): the amount of thermal energy impress on a surface, a certain distance from the source, generated during an electric arc event. # Incident Energy (IE) based at defined distance # IEEE 1584- 2018 Highlights Definitions  # 125kVA Transformer Exception 2002 vs. 2018 “Equipment below 240 V need not be considered unless it involves at least one 125kVA or larger lowimpedance transformer in its immediate power supply.” Replaced with “Sustainable arcs are possible but less likely in three-phase systems operating at 240V nominal or less with an available short circuit current below 2000 Amps.” # 125kVA Transformer Exception # More equipment must be included in your study What Does this 2018 Change Mean to You ◦ Every device from your 125kVA transformers down to your 30kVA transformers ◦ Could dramatically impact the scope and cost of your facility arc flash hazard analyses ◦ Should be addressed during your next study update or before # 2-second Rule No Change • Basically says most people can move away from an arc flash in less than two seconds, but could be slowed down by: ◦ Obstacles or barriers Being elevated in a bucket Being restrained by other safety equipment, etc. • Your studies professional must “use engineering judgement when applying any maximum arc duration time for incident energy exposure calculations”  # IEEE 1584- 2002 The 9 step program Step1:Collect system and installation data Step2: Determine the system modes of operation • Step3:Determine bolted fault currents • Step4: Determine arcing fault currents Step5: Find protective device characteristics and duration of arcs Step6: Document system voltages and classes of equipment Step7: Select working distances Step8:Determine Incident Energy(IE) for all equipment • Step9: Determine Flash-protection boundary for all equipment # IEEE 1584- 2018 The 10 step program 01. Collect system and installation data 02. Determine the system modes of operation 03. Determine bolted fault currents 04. Determine typical gap and enclosure size based on system voltages and classes of equipment 05. Determine equipment electrode configuration (HCB, VOA, etc.) 06. Determine working distances 07. Calculate arcing current 08. Calculate arc duration (through OCPD) 09. Calculate Incident energy (IE) 10. Determine arc flash boundary for all equipment Note: Black $\\equiv$ new for study engineer, Red $=$ new for software # IEEE 1584-2018 Highlights Electrode configuration  # • VCB ◦ Vertical Conductors in a Box (IEEE 2002) • VCBB # Electrode Configuration Now Includes Five Vertical and Horizontal Configurations ◦ Vertical Conductors in a Box with an insulating Barrier # • HCB ◦ Horizontal Conductors in a Box • VOA ◦ Vertical Conductors in Open Air (IEEE 2002) # • HOA ◦ Horizontal Conductors in Open Air # Electrode Configuration VCB Vertical Conductors in a Box (IEEE-2002) # Electrode Configuration VCBB Vertical Conductors in a Box with a Barrier  # Key Findings VCBB • For LV - IE can be up to 2x that of VCB • Arcing current (Iarc) reported to be higher than VCB • 208V arcs sustained down to 4kA ◦ According to testing electrode shape and gap are important at this level # Electrode Configuration side HCB Horizontal Conductors in a Box  # Electrode Configuration VOA Horizontal Conductors in a Open Air   # Electrode Configuration front  HOA Horizontal Conductors in a Open Air   # Arc Flash VCB Configuration Load side of BKR  # Arc Flash VCBB Configuration # Arc Flash HCB /HOA Configuration # Arc Flash VCB (blue), HCB /HOA (Red) Configuration  # HCB # Examples   600V Drawout Switchgear Electrode configuration makes the biggest difference  600V Drawout Switchgear breaker compartment 600V Drawout Switchgear with Iron Frame # HCB-Transformers # Examples Electrode configuration makes the biggest difference  15kV / 480V Transformer compartments  480V Transformer compartments Arcing fault vs Bolted fault LV System 100ms clearing time  The maximum arcing fault spread is 25-40% higher # Incident Energy vs Bolted Fault 480V system Clearing time100ms  # Incident Energy vs Bolted Fault Box vs Open Air   # Arc Fault vs Bolted Fault MV System  # New Model considers the effect of arc impedance at high fault current levels Incident Energy vs Bolted Fault 4160-SWGR Clearing time100ms  4160V IE Comparison More linear than LV, but bigger spread # VCBB vs. VCB @ 2400Volts IEEE-1584-2018

15 kV MCC

152 at 914.4 mm × 914.4 mm × 914.4 mm

2.3kV

2.6-16.6kA at 42

2700V

320

4.16kV

5.4-40.4kA at 18

480V

400

5 kV MCC

104 at 660.4 mm × 660.4 mm × 660.4 mm

5 kV switchgear

104 at 914.4 mm × 914.4 mm × 914.4 mm

Bus Name

Protective DeviceName at Buskv

Cable junction box

13 at 355.6 mm × 304.8 mm × ≤203.2 mmor355.6 mm × 304.8 mm × >203.2 mm