Adapting IEEE 1584-2002Arc Flash Study Results To A Post .

—Adapting IEEE 1584-2002Arc Flash Study Results to a PostIEEE 1584-2018 Risk AssessmentMarcelo E. Valdes, PE, IEEE Fellow CopyrightABB. All rights reserved.Document ID.:Rev.:

—This presentation is a based on a paper presented at the IEEE 2020 Electrical Safety Workshop in March 2020.CONSIDERATIONS FOR ADAPTING IEEE 1584-2002 ARC FLASH STUDY RESULTS TO A POST IEEE 1584-2018 RISKASSESSMENTMarcelo E. Valdes, PE, IEEE FellowMarcelo.E.Valdes@IEEE.ORG, ABB&H. Landis Floyd, PE, IEEE Life FellowUniversity of Alabama at BirminghamThe method outlined in this presentation was solely created by M. E. Valdes and isnot a product of the ABB company nor is it endorsed or promoted by ABB in any way.The method is not intended to replace a well performed arc flash study by qualifiedpersonnel using the latest applicable standards and generally accepted practices.The method is solely intended to provide an estimating tool that may be useful inthe process of risk analyses associated with evaluating if PPE has a high enough arcrating, under certain identified limited conditions, to exceed the incident energy thatmay be calculated by an Arc Flash study performed using IEEE 1584-2018 under thesame identified limited conditions.

—Old AF study New AF science PPE was selected with an IEEE 1584-2002 AF studyPPE good enough for my task now that IEEE 1548-2018 hasestablished a new science?Am in conformance with the legal requirements? Is ignoring IEEE 1584-2018 the right thing to do from a “riskAssessment and control perspective? Does the worker have adequate PPE for the potential severity ofan AF event based on the “new” science?

—A Paradigm Shift“Ensuring that American workplaces are safe will require a paradigm shift, with employers going beyond simply attempting to meet OSHA standards, to implementing risk-based workplace injury and illness preventionprograms.”Assistant Secretary David Michaelsletter to the OSHA staffJuly 19, 2010

—Is that, really, the right question?Is this a legal matter? PerhapsIs it a safety matter? DefinitelyPrimarily it is a “Risk Analysis” question!

—“Risk” in 70E Risk Management, Needs:1. Communication & consultation2. Establishing risk assessment context &objectives3. Risk assessment4. Risk treatment5. Recording/reporting risk assessment results& treatment decisions6. Monitoring & reviewing risks

—“Risk” in 70E Risk Assessment, Part of risk management involving:1.Identifying sources of risk2.Analyzing risk sources to estimate risk level3.Evaluating risk determine if risk treatment is required

—“Risk” in 70E Risk Analysis, must be:1. Integral to organizational processes & decisions2. Systematic, structured, & timely3. Use best available information4. Accounts for human & cultural factors5. Dynamic, iterative & responsive to change6. Facilitates continual organization improvement

—Why bother asking?ParameterIEEE 1584 2018 is very different from 2002 version2002 version was good, the 2018 version is betterInputs for the calculations are different Electrode orientation & arc environment werenot considered beforeVoltage (Voc) 208 - 600 V & 1kV - 13.8 kVFrequency50 - 60 HzCurrent @ LV (Ibf)700A - 106kACurrent @ MV (Ibf)700A-63kAGap (G) @ LV10 - 40 mmGap (G) @ MV13 - 152 mmWorking Distance (D)Typically 15-36 InchesSystem groundingUsed20182018 model208 V - 15 kV50 - 60 Hz 600 V 500 A - 106 kA 600 V 200 A - 65 kA 600 V 6.35 - 76.2 mm 600 V 19.05 - 254 mm 12 inchesIgnoredvariable, 49" maximum forEnclosure Assumed per voltage & gapany 1 dimensionElectrodeVCB, VOA VCB, VOA (vertical only)configurationsVCBB, HCB & HOAVertical orparallel intobarrierVCBBHorizontal orperpendicularHCBVertical orparallelVCB2002 & 20182002 model2018

—Why bother asking?And gap is now a variableIs the arc pointing at the worker or not?Is the arc constrained or free?Is it an itty-bitty arc, or a great big long one?Are the differences important ? Do we care?Parameter2002 modelVoltage (Voc) 208 - 600 V & 1kV - 13.8 kVFrequency50 - 60 HzCurrent @ LV (Ibf)700A - 106kACurrent @ MV (Ibf)700A-63kAGap (G) @ LV10 - 40 mmGap (G) @ MV13 - 152 mmWorking Distance (D) Typically 15-36 InchesSystem groundingUsed2018 model208 V - 15 kV50 - 60 Hz 600 V 500 A - 106 kA 600 V 200 A - 65 kA 600 V 6.35 - 76.2 mm 600 V 19.05 - 254 mm 12 inchesIgnoredvariable, 49" maximum forEnclosure Assumed per voltage & gapany 1 dimensionElectrodeVCB, VOA VCB, VOA (vertical only)configurationsVCBB, HCB & HOA

—Relationships are not simpleEquations are complex, no need to go there for this analysis if one can make some assumptions!65342𝐼𝐼𝑎𝑎𝑎𝑎𝑎𝑎 𝑉𝑉𝑉𝑉𝑉𝑉 10(𝑘𝑘1 𝑘𝑘2𝑙𝑙𝑙𝑙𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘3𝑙𝑙𝑙𝑙𝐺𝐺) (𝑘𝑘4 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘5 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘6 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘7 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘8 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘9 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘10 ) )𝐸𝐸𝑉𝑉𝑉𝑉𝑉𝑉 12.55250𝑇𝑇 10𝑘𝑘3 ��𝑉1𝑘𝑘1 𝑘𝑘2 𝑙𝑙𝑙𝑙𝐺𝐺 𝑘𝑘11 𝑙𝑙𝑙𝑙𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘12 𝑙𝑙𝑙𝑙𝐷𝐷 𝑘𝑘13 ��𝑉𝑉𝑉𝑉𝑉 𝑙𝑙𝑙𝑙765342𝐶𝐶𝐶𝐶𝑘𝑘4 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘5 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘6 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘7 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘8 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘9 𝐼𝐼𝑏𝑏𝑏𝑏 𝑘𝑘10 𝐼𝐼𝑏𝑏𝑏𝑏

—2002 study (VCB)System Voltage (Voc)Fault current (Ibf)Risk analysisTCCIarc timeArcing Gap (G)Grounding methodArcing Gap (G)IarcRisk analysisEi PPE2002timeWork DistanceOnly 1 electrode description VCB, box is always standard There is open as well but ignoring in this situationIn 2018 electrode description became a big factor!Grounding method no longer a factorGap & box size also factors but will those change?

—2002 study (VCB)System Voltage (Voc)Fault current (Ibf)System Voltage (Voc)Fault current (Ibf)Arcing Gap (G)Risk analysisTCCIarc timeHCB, VCB or VCBBArcing Gap (G)IarctimeRisk analysisEi Work DistanceHCB, VCB or VCBBBox sizeVCB, VCBB or HCB impact Iarc & Ei directly, & Iarc impacts time which also impacts Ei !Electrode orientation is now “a” big factor!Gap & box size also factors but will those change? Larger box will lower EiPPE2018

—Gap and electrode orientation IarcGap probably will not change unless it’s recognized the gap needs to be larger than previously used. If alarger gap is needed it’s a more complex problem.If the gap is smaller than what was used in calculation then analysis is conservative, for this purpose itcan be ignored.In a 2018 Arc Flash study, if not sure about “gap” use a larger gap

—Impact of gap on arcing current!480V, 32mm gap, Std LV boxHigher Iarc equal or faster speed protection neverslower!Iarc (kA)Over an important region the 2018 Iarc is the 2002Iarc!!!1584-2018,VCBBHCBVCB1584-2002, VCBIbf (kA)

—208V, similar to 480V except arcing current really flattens out208V, 25mm gap, Std LV boxSimilar relationships at 208V. Its alsosimilar at 600VWhat happens at 200kA Ibf ?Iarc (kA)Flattening of the arcing current atsome point more Ibf drives little morearcing current1584-2018,VCBBHCBVCB201510Arcing current can be much lowerthan traditionally calculated faultcurrents, specially at very high valuesof fault current and in lower voltagesystems!1584-2002, VCB50Ibf (kA)05101520253035404550556065707580859095100

—Important point100.00Fuse TCCCB TCC Protection will be equal or faster over that range ofIbf Never slower!Fuse curve’s & CB’s TOC portion of curves are steeperthan constant energy boundaries If Iarc increases the protection will never be slower!10.00Time (Sec.)For a useful range of Ibf , same Voc & gap, for allVCB/HCB/VCBB; Iarc will be higher in a 2018 study1.00Constant EnergyBoundary0.10Increasing Iarc0.0101Iarc(kA)10100

—Ei not so clear480V, 32mm gap, Std LV box, 18 in, cm2151050cal/cm220208V, 25mm gap, Std LV box, 18 in, 100ms101584-2002, VCB1584-2002, VCBIbf (kA)051015202530354045505560657075808590951000Ibf (kA)05101520253035404550556065707580859095For VCBB & VCB, all else equal, the 2002 study may be adequate or even conservative over a wide range of situations, butnot alwaysHCB, on the other hand but there are more variables in the new equationsBut above assumes time is equal! If the 2002 vs 2018 time are different .100

—Gap, 25, 32 & 51mm (1, 1.25 & 2 inches), VCB, 480V5020Incident energy (Ei)Increases with gap45Arcing current (Iarc)Decreases with gap403515Gap EiIarc (kA)2510cal/cm2302015Gap10Gap5 Iarc Ei50Ibf (kA)051015202530354045500556065707580859095100Ibf (kA)0510Lower Iarc is harder to detect, may cause protection to slowRegardless the decreasing Iarc, Ei increases because the arc is longerEffects may be small, but they may add up specially if protection slows1520253035404550556065707580859095 100

—Constant Energy Boundary, A tool1000A CB100.00480V, 32mm, 18”, VCB8 cal/cm210.00Time (Sec.)1584-2018 For any one value of Iarc, curve shows the time needed toproduce a specific value of Ei. Notice, for same target Ei, 2018 allows more time at thesame value of Iarc But the AF study may tell you Iarc for a 2018 based AFstudy, we do not know what it would be for a 2018calculation But we know that for a certain range of IbF the 2018 Iarc willbe higher hence the OCPD will be equal speed or faster!1.001584-20020.100.0101Iarc(kA)10100

—Transpose to Ibf5010.00.4540 Since we do not need OCPD clearing time wedo not need actual Iarc. The vertical lines bound the range of Ibfwhere we know the 2018 Iarc will be largerthat the 2002 Iarc. If the gap, working distance & voltage are thesame & Ibf is the same between 5kA to85kA the Ei will be less for VCB with thesame OCPD.30252015.1051.000Ibf (kA)01020304050Time (Sec.) Plotting at Ibf allows the two lines to becompared to each other.Iarc (kA)350.100.011Ibf(kA)1010060708090100

10.00 2018 VCB is always easier but for VCBB it dependson the exact Ibf And for HCB it is always worse!!1.00 But this assumes the Ei target performance is thesame for 2002 & 2018 studies Time (Sec.)—VCB, VCBB & HCB1584-2002 Energyboundary/ vs IbfVCBHCBChances are that the 2002 PPE decision selected a PPEhigher than the actual exposure because PPE choicesare limited by choice & availability there is a margin0.100.01VCBB1Ibf(kA)10100

—One more consideration Generally a PPE level selected or recommended is than the Ei calculated. Table above: 9.5 25, 11.8 25, 38 40, 31.1 40 Can the margin absorb the extra energy the new exposure may cause?

—15.6 calories calculated; 25 calorie PPE identified An almost 10 calorie margin, enough toaccommodate the new calculations?Improperly identified as HRC here!

—With the right graph any situation can be analyzed6Time (Sec.)81.0058Time (Sec.)1.00If Ei calculated was 6 cal/cm2 but 8 PPE wasselected. A task that may now have VCB orVCBB exposure is still covered by the 8 cal/cm2PPE. For HCB, for some Ibf range, Ei may exceedPPE selected. A more exact calculation will beneeded to make sure!0.100.10If Ei calculated was 5 cal/cm2 & 8 call PPEwas selected. HCB energy may not exceedselected PPE!8 c/cm 2 480V, G 32mm, WD 457.2mm, VCB Std LV box8 c/cm 2 480V, G 32mm, WD 457.2mm, VCBB Std LV box1584-2002 6 c/cm 2 480V, G 32mm, WD 457.2mm, VCB Std LV box8 c/cm 2 480V, G 32mm, WD 457.2mm, HCB Std LV box0.011Ibf(kA)101008 c/cm 2 480V, G 32mm, WD 457.2mm, VCB Std LV box8 c/cm 2 480V, G 32mm, WD 457.2mm, VCBB Std LV box1584-2002 5 c/cm 2 480V, G 32mm, WD 457.2mm, VCB Std LV box8 c/cm 2 480V, G 32mm, WD 457.2mm, HCB Std LV box0.011Ibf(kA)10Without Iarc or understanding the OCPD the method allows determination if a new electrode exposure presentsunacceptable risk using only the 2002 based study!. But one needs a chart to represent the specific scenario!100