Arc Flash Safety EGuide - Power Management Solutions Eaton
CSEArc Flash SafetyeGuideSponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersSponsored By
Sponsor OverviewSponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersAt Eaton, we’re energized by thechallenge of powering a world thatdemands more. With over 100 yearsexperience in electrical power management, we have the expertise tosee beyond today.Sponsored ByWhatever the challenge, Eaton delivers with innovative solutions. Powerdistribution and circuit protection.Backup power protection. Controland automation. Lighting and security. Structural solutions and wiringdevices. Solutions for harsh andhazardous environments. And engineering services.Eaton is an expert partner for helpingengineers specify electrical systemsthat exceed the exacting standards ofcommercial construction, data centers and other projects. From groundbreaking products to commissioningsupport, critical industries all over theworld count on Eaton.We power businesses with reliable,efficient and safe electrical solutions.Along with the personal service,support and bold thinking to answertomorrow’s needs today. Follow thecharge with us.Eaton.com/followthecharge2
Preventing Arc Flash Incidents By DesignSponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersSponsored ByUnderstanding electricaldistribution equipment andits associated risks can helpreduce incident energy levelsand save lives.By Bruce W. Young, PE, BalaConsulting Engineers Inc., Kingof Prussia, PA.Anyone involved with electricaldistribution systems—either as a design engineer, commissioning agent,or contractor—for more than fiveyears probably has been directlyinvolved in an arc flash incident orhas heard of one.According to NFPA 70E: Standardfor Electrical Safety in the Workplace, arc flash is a “dangerous condition associated with the releaseof energy caused by an electricalarc.” It is measured in terms of arcflash incident energy, which is usedto determine the appropriate levelof personal protective equipment(PPE), and in terms of an arc flashprotection boundary.An arc flash is the result of anelectric current passing through airas the result of conductor failure,equipment failure, or the accidentalconnection between voltage sourcessuch as dropping a tool acrossbuses in distribution equipment. Theflash is immediate but the resultantrelease of energy can cause severeinjury, and possibly death. There isa potential for a tremendous amountof heat to be released, which canresult in overpressures, as well asflying debris. The energy releasedcan cause temperatures exceeding 35,000 F, which can vaporizesteel, copper, and aluminum. Inhaling these vaporized metals could befatal. Injuries or fatalities could occurif personnel are in the area in frontof an arc flash, which could sendprojectiles such as parts of metalbuses away from the blast. Also,molten metal can cause significantburns, and the sudden air pressureThis arc flash label indicates that the breakersettings used in Figure 1 result in conditionsthat require personnel to wear Category 3PPE within the flash boundary.Courtesy: Bala Consulting Engineers Inc.increase can knock personnel offtheir feet.Each year, more than 2,000 peopleare treated in burn centers for injuries from arc flash incidents. Manyinjuries caused by arc flash incidentscan be prevented. Not working onor around energized equipment maybe the simplest way to avoid injury.Scheduling maintenance outagesmay seem like a bother, but willeasily offset the loss of production,unscheduled outages, and equipment damage that may occur with anarc flash incident.Arc flash hazard analysisSometimes working on live electrical equipment may be necessary.Appropriate PPE is required whenworking on or around energized electrical equipment. An arc flash hazardanalysis is required by NFPA 70E.This determines the arc flash boundary, the incident energy at the working distance, and the level of PPEthat must be used within the arc flashboundary.Procedures for performing an arcflash hazard analysis can be foundin IEEE 1584: Guide for PerformingArc Flash Calculations. Some of thefactors that determine the amount ofincident energy include:3
Sponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersSponsored By The available fault current at thecircuit: This is the amount of currentthat could flow into the circuit in theevent of a fault. This is calculatedin the short-circuit analysis. Factorsthat determine fault current are theavailable fault current of the powersource (typically available from thelocal power utility), the impedanceof the transformers that supply thecircuit, length and type of conductorsin the circuit, and motor contribution.At first, it may seem counterintuitive,but higher fault currents may actually reduce the flash hazard becausethey will decrease the overcurrentdevice clearing time, which reducesthe flash hazard. The operating characteristics ofthe overcurrent protective devicesin the circuit: These vary with thetype of device used. These characteristics are determined by simplefixed settings on thermal magneticbreakers, fuse melting curves, andmultiple pickup settings on relaysand solid-state breakers. Settings foradjustable devices are determined ina coordination study. Equipment labeling requirements: For distribution equipmentthat has a main overcurrent protective device, two labels may be required: one label for the energy levelat the line sideof the deviceand anotheron the loadside of the device. Energylevels at theline side andload side maybe significantly different.This differential shouldbe identifiedto providemaintenancepersonnelwith information regardingpotential arcflash hazards.Even with themain breaker opened, the line side ofthe main is still energized.Equipment labelingAfter the arc flash hazard analysisis completed, warning labels areprinted and affixed to the electricalequipment. The labels should includethe level of PPE required, the flashhazard boundary, the flash hazard,the shock hazard, and approachdistances.After the study is completed andthe labels are installed, work on thisequipment or routine maintenancewill likely be required at some point.Work that may be required could bethermal scans to check for equipment hot spots, racking out a breakerfor routine maintenance, or installinga new circuit breaker to serve newloads.Regardless of the work to be done,personnel must follow the appropriate safety procedures. Observe thelabel to determine the proper PPE4
Sponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersThis arc flash label indicates that the breakersettings used in Figure 2 result in conditionsthat reduce the boundary hazard and lowerthe PPE requirement to Category 0.Courtesy: Bala Consulting Engineers Inc.exists. Therefore, it is critical that personnel working on electrical distribution equipment be trained in properprocedures, and that they wear theappropriate PPE.White Paper:Arc Flash Safety In400V Data CentersFigure 1: This graph shows breaker settings and the corresponding time-current curve forselective coordination requirements. Courtesy: Bala Consulting Engineers Inc.Sponsored Bylevel, gear up, and carefully proceedto perform the necessary work. PPEmay be as simple as safety glasses,gloves, and untreated cotton—or itcould include a full face shield andprotective suit. For minor or simplemaintenance tasks, the temptationmay be to proceed without properPPE to save a few minutes. But evenwith the most careful work, accidentscan happen, and the potential forserious, life-threatening injuries stillReducing incident energy levels at alocation where electrical work is to beperformed reduces the level of PPErequired when working on energizedcircuits at that location. However,energy incident level reduction doesnot eliminate PPE requirements.Figure 1 shows a time-current curve(TCC) for a 1,600 A, 480 V, solidstate trip-unit circuit breaker withadjustable long time pick-up, longtime delay (LTD), short time pick-up5
100% arcing fault level of 3,540 Awill last approximately 13 sec. Usingthe maximum arcing exposure timeof 2 sec as recommended in IEEE1584 results in an arc flash hazardof 22 Cal/cm2 and requires Category3 PPE as indicated on the warninglabel (see inset). Energy levels above1.2 Cal/cm2 can cause a temperaturerise that will result in second-degreeburns on exposed human skin.Sponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersFigure 2: This graph shows breaker settings and the corresponding time-current curve forreducing the arc flash hazard. Courtesy: Bala Consulting Engineers Inc.Sponsored By(STPU), short time delay (STD), andinstantaneous settings. These settings allow the breaker’s operatingcharacteristics to be adjusted. Thesettings in Figure 1 were selected toachieve selective coordination withupstream and downstream overcurrent protective devices to isolate thepotential fault as close to the faultas possible. With these settings, the85% arcing fault level of 3,009 A willlast approximately 19 sec, and theWhen energized maintenance isrequired for this equipment or downstream equipment, the energy leveland required PPE may be reducedby setting the LTD to 0.5, the STPUto 1.5, and the STD to instantaneous,with the resulting TCC shown in Figure 2 and its corresponding warninglabel shown in the inset. These settings reduce the arcing fault durations(the 85% and 100% fault levels) to0.02 sec. This means the breaker willclear the fault more quickly. The flashboundary is reduced from 105 in. to15 in., and the flash hazard has beenreduced from 22 Cal/cm2 to 0.86 Cal/cm2. Note that some breaker designsmay not allow adjusting these pointswhile energized.Reducing incident energyAfter the maintenance has been performed, the original settings can berestored. Please note that adjusting6
Sponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersSponsored Bythe trip characteristics of an energized breaker may also cause a nuisance trip to occur. Before performingthis work, the facility staff should bemade aware of this possibility andinformed that a temporary poweroutage could ensue. If this happens,the breaker could be immediatelyreset so the outage would be nolonger than a few sec, but for criticalfacilities, such as hospitals and datacenters, even this temporary outagecould be detrimental to the facilityoperation.Many manufacturers offer maintenance switches that can decreasethe time an arcing fault is allowed toexist, thereby reducing the incidentenergy exposure. This function isusually enabled with a keyed switch,often located out of the hazardboundary. Some manufacturers offeran arc fault detection circuit, whichtypically uses a photoelectric sensorto differentiate between an overload,a fault, and an arc flash. Others offerzone-selective interlocking betweenthe levels of the overcurrent protective devices. Using this feature canreduce clearing time if a fault occurs,thereby reducing the incident energyand the level of required PPE.Another method to reduce exposure during device operation is witha remote operating station locatedoutside the flash hazard boundaryarea. The station allows personnel tooperate the device without having towear PPE. Remote operating stationstypically provide positive feedback—usually an indicating lamp—thatverifies the open or closed status ofthe device.For many critical facilities such asdata centers, dual power paths to theequipment are provided. This allowsthe electrical distribution equipmentto be de-energized while maintainingoperation. Dual paths require additional distribution equipment—almosta mirror image of all the distributioncomponents. This increases initialinstallation costs, but when properlydesigned and installed, complete isolation of any component in the electrical distribution system is possible.Dual paths give personnel the abilityto perform maintenance and testingon de-energized equipment.Understanding arc flash and itspotential hazards, calculating riskmitigation, knowing the importanceof labeling, and the proper use ofPPE can maintain the effective useof electrical distribution equipmentthrough equipment maintenance andupgrades—and ultimately save lives.Learning from experienceBeing an electrical engineer for morethan 25 years, I’m aware of at least15 arc flash incidents and have beendirectly involved in three. The following is an account of my experiencewith one of those incidents.Our design-build team was addinga new distribution section onto anexisting service entrance switchboardthat supports a critical infrastructuredistribution system. Installing the newsection required the switchboard tobe de-energized. Shutdown arrangements were made, the method-ofprocedure (MOP) was in place, andthe new section was on-site andready to be connected. Work was tobegin at 1 a.m. on a Sunday and tobe completed by 6 a.m.—more thanenough time (we thought) to accomplish our task.As 1 a.m. approached, we had portable generators running, flashlights inhand, all the equipment was powereddown, and we were ready to begin.The first step in the MOP was to tripthe main disconnect using the groundfault test relay. We pressed the tripbutton; nothing happened. Becausethe equipment was more than 20years old and probably had not beentested in some time, the consensuswas that the ground fault relay prob-7
Sponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersSponsored Byably had a blown fuse and could berepaired after the main was opened.ily, no one was injured, but we werea bit shaken.Because there was a limited amountof time to perform the work, the decision was made to manually openthe main. The main was a boltedpressure-fused disconnect, so theelectrician tripped the “open” lever.Nothing happened. He rechargedthe trip spring, tried to open it again,but the switch did not open, but wedid detect some movement. He triedagain, but it still did not open. Looking back, we should have stoppedhere, delayed the project, and calledin a service technician for the equipment. But, there was a lot of pressure to finish the work and delayingthe project was not an option.Upon further examination, we determined that because the switch hadnot been operated in several years,the lubricant on the operating linkage had deteriorated. Cycling theswitch, along with the deteriorationof the lubricant, had resulted in amechanical failure of the linkage,and a piece of the linkage had fallenacross the load side bus causingthe arc flash. Although no one wasinjured, the flash damaged the mainswitchboard, which necessitatedusing a portable generator while theswitchboard was being repaired.A few access panels were removedto allow switch inspection. Thetrip spring was recharged and wetried to open the switch again, butstill with no success. The operating mechanism did move a smallamount, so the decision was madeto keep trying. As we kept trying, theoperating mechanism moved a littleeach time, so we thought the switchwould open with just a few moretries. We left the panels off for easyinspection. We tried a few moretimes and there was a large flash,with lots of smoke and noise. Luck-About the authorBruce W. Young is senior associate and the electrical departmentmanager at Bala Consulting Engineers Inc. in King of Prussia, Pa. Hisexpertise is in critical power distribution systems and on-site powergeneration systems. He is a memberof NFPA and the 7x24 Exchange,and a U.S. Air Force veteran.8
Integrating Electrical Safety With DesignSponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid SubstationTransformersWhite Paper:Arc Flash Safety In400V Data CentersSponsored ByIntegrating maintenance requirementsinto the design of an electrical systemis an important first step to provideworkplace safety.By Kenneth Mastrullo, MESConsulting Services Inc.,Weymouth, Mass.Safety-related maintenance requirements for electrical equipment areoutlined in Chapter 2 of NFPA 70E:Standard for Electrical Safety inthe Workplace, but they are oftenoverlooked to the detriment of bothworker safety and a company’sreputation. Using the concepts andstrategies in Chapter 2 can enhancethe company’s worker safety, productivity, and positive image.Integrating maintenance requirements into the design of an electricalsystem is an important first step toprovide workplace safety. There aretwo elements that comprise maintenance tasks at a facility: technicalexpertise and safety considerations.Chapter 2 provides a great foundation to understand the fundamentalsof what every company requires tooperate and maintain the electricalsystem in a safe manner after it hasbeen commissioned. Lack of propermaintenance could not only affectthe operation of production at a facil-ity, it could have a catastrophic effectfor workers.In difficult economic times it is common to eliminate or decrease thefrequency intervals of preventivemaintenance for electrical systems.However, lack of adequate maintenance often results in the failure ofovercurrent protection devices tooperate within the prescribed rangefor opening. An elongated openingtime, which can be measured in afew tenths of a second, can have asignificant difference in the arc flashexposure to a worker. The idea isthat the calculations assume a certain opening time, if the device failsto operate in that time, then the arcflash study/values are incorrect, andthe worker may not have the properpersonal protective equipment(PPE). If the worker is not protectedfor the magnitude of the exposure, itcould result in a significant injury ordeath.An example of what can happenwhen electrical equipment is notproperly maintained occurred in2010. In this case the electricalequipment was installed in the 1970sand was never maintained, calibrated, or exercised. When the arc flashoccurred, the main breaker in theswitchboard did not trip. The circuiteventually opened at a fuse locatedon the primary side of the site transformer. This is an example of thedifference in magnitudes that couldresult in an actual event comparedto what could be anticipated usingthe NFPA 70E tables or arc flashcalculations. The difference in actualand anticipated tripping time of theovercurrent protection device due tofailure to maintain equipment resulted in an exposure to the worker of 15Cal/cm2. A typical protective workerstrategy for this installation would beCategory 2 in accordance with Table130.7(C)(15)(a) of NFPA 70E. Thiswould require 8 Cal/cm2 outer layerarc rated clothing with 100% cottonunderlayers.9
Sponsor OverviewPreventing Arc FlashIncidents By DesignIntegrating ElectricalSafety With DesignProtection, Arc FlashMitigation Using InternalVFIs In Liquid Substat
After the study is completed and The available fault current at the circuit: This is the amount of current that could flow into the circuit in the event of a fault. This is calculated in the short-circuit analysis. Factors that determine fault current are the available fault current of the
Arc Flash Facts Arc Flash Fact Sheet Brady Arc Flash Training Aids Promote awareness of the dangers associated with arc flash accidents and make sure your workers know how to protect themselves! Poster Highlights the common causes of arc flash and provides safe work practices and personal protection equipment requirements
130.5 Arc Flash Risk Assessment. An arc flash risk assessment shall be performed and shall: (1) Determine if an arc flash hazard exists. If an arc flash hazard exists, the risk assessment shall determine: a) Appropriate safety-related work practices b) The arc flash boundary c) The PPE to be used within the arc flash boundary
Arc-flash analysis has been performed for this site (calculations, labeling and Arc-flash hazard analysis. arc-flash boundaries). Electrical safety training for operators and maintenance personnel. Arc-flash hazard training for operators and maintenance personnel. Arc-flash hazard training focusing on selecting and using the proper PPE.
Bussmann series arc flash relay system 1. Introduction Eaton's BussmannTM series arc flash relay (EAFR) system is a combination of arc flash relay modules and sensors designed to detect and clear arc flash events in low and medium voltage electrical assemblies. An arc fault is the most devastating type of fault in medium
130.7(C)(15)(b) specify arc flash PPE category 1 or 2b Arc Flash Suit A total clothing system consisting of arc-rated shirt and pants and/or arc-rated coveralls and/or arc flash coat and pants (clothing system minimum arc rating of 40) Situations where a risk assessment indicates that PPE is required and where Table 130.7(C)(15)(a) and table .
The work permit shall include the results of an Arc Flash Risk Assessment The Arc Flash Risk Assessment shall determine 130.5(1) – Appropriate safety related work practices Including Maintenance Switching – Arc Flash Boundary – PPE to be used within the arc flash boundary NEC 110-16 requir
Warning: Arc Flash Clothing protects from thermal effects of arc flash only. CLY 574 020 CLY 574 075 CLY 574 031 Dual stage front closure with plastic zip and FR Velcro storm flap on 31-100 cal/cm2 jacket designs. Safety Glasses CE marked, meets current EN166 standard only Anti-fog, anti-scratch, anti-static 99.9% UV protection
Arc Flash Training (NFPA 70E - 110.6) Personnel exposed to Arc Flash Hazards shall be trained in: Identifying potential Arc Flash Hazard tasks and locations The safe work practices necessary to eliminate injury from an Arc Flash Hazard The use and care of PPE. NFPA-70E 2018 Retraining
