20120504 LISAT slides Dube

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Arc Flash Mitigation Strategies for MC Switchgear; Mike Dube

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20120504 LISAT slides Dube

  1. 1. ARC FLASH MITIGATION STRATEGIES for METALCLAD SWITCHGEAR PEDERSEN POWER PRODUCTSTh Sign o Quality e f
  2. 2. Discussion Topics Arc Flash Standards Arc Flash Prevention Arc Flash Protection Mitigation Techniques
  3. 3. Arc Flash Hazards Molten Metal Intense Heat Droplets 35,000F Flying Objects & Shrapnel Toxic Gases Copper Solid to Intense Vapor Expansion Light Flash 67,000 Times Sound BlastPressure Wave
  4. 4. ARC FLASH STANDARDS PEDERSEN POWER PRODUCTSTh Sign o Quality e f
  5. 5. IEEE Standard 1584Contains calculations used to determinesafe boundary distances for unprotectedpersonnel and the incident energy at theworking distance for qualified personnelworking on energized equipment.
  6. 6. IEEE Standard 1584 Incident Energy Calculation for Arc Flash in a Cubic BoxE =1038.7D-1.4738 x T[0.0093F2-0.3453F+5.9675]E = Incident Energy in cal/cm2D = Distance to arcing pointT = Time to clear arcing faultF = Available bolted fault short circuit current
  7. 7. NFPA-70E-2009 Standard for Electrical Safety in the WorkplaceUtilizes IEEE 1584 methods forcalculating incident energy onspecific electrical equipment andprovides guidelines for the PPEclothing required based on theincident energy level.
  8. 8. National Electric CodeRequires labeling of electrical equipmentto warn qualified personnel of the dangerof electric arc flash.Refers to NFPA-70E as a guide forquantifying the hazard.
  9. 9. Arc Flash Warning LabelCompliance with National Electric Code
  10. 10. Arc Flash Warning Label
  11. 11. OSHA 29 CFR Part 19101910.333 Selection and Use of Work PracticesSafety-related work practices to prevent injuries resultingfrom either direct or indirect electrical contact, whenwork is performed near or on equipment or circuits whichmay be energized.1910.335 Safeguards for Personal ProtectionPPE shall be used to protect employees fromelectrically related injuries while that employee isworking near exposed energized parts. Subpart S, Appendix A References NFPA-70E for Electrical Safety Practices
  12. 12. ARC FLASH PREVENTION PEDERSEN POWER PRODUCTSTh Sign o Quality e f
  13. 13. Arc Flash PreventionDON’T WORK ON ENERGIZED ELECTRICAL EQUIPMENT!
  14. 14. Causes of Electric Arc Flash  Contact with Live Parts  Unsafe Work Procedures  Misoperation  Insufficient Maintenance  Overvoltages  Insulation Failure  Entry of Small Animals
  15. 15. Arc Flash Prevention Maintain Sound Safety Practices Prevent Entry of Critters Use IEEE Metalclad Standards Prevent Moisture Ingress Proper Insulation System Design Monitor for Partial Discharge Monitor Bus Temperatures
  16. 16. IEEE Standard C37.20.7“There is little likelihood of an internal arc inequipment meeting the requirements of IEEE StandardC37.20.1-2002 or IEEE Standard C37.20.3-2001. Thereis even less likelihood of an internal arc in equipmentthat has insulated bus, compartmentalization, barriers,and interlocks, such as those described in IEEEStandard C37.20.2-1999.” Metalclad Switchgear Design Standard
  17. 17. Metal Enclosed Switchgear Line Terminals Uninsulated Bus Load break air switch Everything in Same Compartment Exposed Live Parts with Fuse Door Open Load Terminals Ground bus
  18. 18. Metalclad Switchgear Relay, Controls Primary buses and and connections covered Instrumentation with insulation Shutters cover Main bus Primaries whenPrimary circuits, no breaker installedrelays, meters,and controlsisolated in own CT barrier CTgrounded metal Loadcompartments bus Movable Shutters CT Breaker Compartment Ground bus
  19. 19. Metalclad Switchgear Relay, Controls and Instrumentation Main bus Steel barrier CTNo primary circuits Loadexposed with busbreaker installed Vacuum CT Breaker Ground bus
  20. 20. Arc Flash Prevention Maintain Good Safety Practices Prevent Vermin Entry Use IEEE Metalclad Standards Prevent Moisture Ingress Proper Insulation System Design Monitor for Partial Discharge Monitor Bus Temperatures
  21. 21. Moisture Prevention IEEE Tested Enclosure Design Use Extended Life Sealants IEEE C37.20.2 Section 6.2.10 Ventilate Test Criteria Cable Compartment7.1 gallonsFilters/Screens rate• Maintain per minute flow60psi Dualwater pressure• Use min Strip Heaters10 ft. Min Distance from Joints• Monitor Strip HeatersAgainst 2 Surfaces at each Joint• Seal Unintentional Openings Apply Quality Protective Finish
  22. 22. Arc Flash Prevention Maintain Good Safety Practices Prevent Vermin Entry Use IEEE Metalclad Standards Prevent Moisture Ingress Proper Insulation System Design Monitor for Partial Discharge Monitor Bus Temperatures
  23. 23. Insulation Materials 95kV BIL Rated InsulatorsFluidized Bed Epoxy Bus Insulation Cycloaliphatic bus supports PVC Insert
  24. 24. Arc Flash Prevention Maintain Good Safety Practices Prevent Vermin Entry Use IEEE Metalclad Standards Prevent Moisture Ingress Proper Insulation System Design Monitor for Partial Discharge Monitor Bus Temperatures
  25. 25. Partial Discharge Monitoring Signal sent to InsulGardRFCT #1 detects partial Relaydischarges internal toswitchgear compartment.RFCT #2 detects partialdischarges in Customer’scables up to 100 ft fromswitchgear
  26. 26. Partial Discharge Monitoring
  27. 27. Arc Flash Prevention Maintain Good Safety Practices Prevent Vermin Entry Use IEEE Metalclad Standards Prevent Moisture Ingress Proper Insulation System Design Monitor for Partial Discharge Monitor Bus Temperatures
  28. 28. Temperature Monitoring Bus Joint Wireless Parasitically Powered Temperature Detectors for Medium Voltage Switchgear Straight (under development) Bus
  29. 29. Output Through InternetProtection system configurationTemperature input from sensorsCurrent Input from CT’sCalculate and Predict a ProblemEmail/Alarm notification
  30. 30. ARC FLASH PROTECTION PEDERSEN POWER PRODUCTSTh Sign o Quality e f
  31. 31. Arc Flash Protection Train Personnel Wear Proper PPE Install Warning Labels Maintain Good Safety Practices Build Sturdy Enclosure Reduce the Human Interface Redirect the Blast Energy
  32. 32. Safety Practices De-Energize Equipment Use Lockout/Tagout Procedures Latch and Secure All Panels Label Line and Load Side Bus Isolate Potential Backfeeds Open Tie Breaker/Redundant Sources Ground De-Energized Conductors
  33. 33. Safety PracticesIEEE C37.20.6-2007 G&T TESTING STANDARD  First G&T Standard  Established Formal G&T Tests  BIL Withstand  AC Hipot 1-minute  Momentary For 10 Cycles Per C37.20.2  K*I 2 Seconds Per C37.20.2  Interlocking (Upper & Lower)  500 Insertions and Removals
  34. 34. Safety PracticesBall Type Ground & Test Device
  35. 35. Safety Practices Ground Conductor Sizing 25kA for 2 seconds Requires three (3) – 350mcm cables per phase (total of 9 grounding cables) Ground Conductor Sizing 31.5kA for 2 secondsRequires three (3) – 500mcm cables per phase(total of 9 grounding cables)
  36. 36. Safety Practices
  37. 37. Arc Flash Protection Train Personnel Wear Proper PPE Install Warning Labels Maintain Good Safety Practices Build Sturdy Enclosure Reduce the Human Interface Redirect the Blast Energy
  38. 38. Sturdy Enclosure Design Use Only 11 Gauge Steel Weld Cubicles Two Walls Between Sections Heavy Duty Door Hinges Heavy Duty Door Latches
  39. 39. Arc Flash Protection Train Personnel Wear Proper PPE Install Warning Labels Maintain Good Safety Practices Build Sturdy Enclosure Reduce Human Interface Redirect the Blast Energy
  40. 40. Reduce Human Interface Opening & Closing Breaker Relocate control switch Use remote communications Use local HMI Use remote control station Use Remote Operator Use Time Delay Control Switch
  41. 41. Reduce Human Interface Remote Breaker ControlSmart Remote Control Station
  42. 42. Reduce Human Interface Remote Breaker Control ELECTROSWITCH
  43. 43. Reduce Human Interface Remote Breaker RackingRemote Breaker Racking Motor Remote Breaker Racking Motor
  44. 44. Reduce Human Interface Remote Breaker Racking
  45. 45. Reduce Human Interface Remote Breaker Racking
  46. 46. Arc Flash Protection Train Personnel Wear Proper PPE Install Warning Labels Maintain Good Safety Practices Build Sturdy Enclosure Reduce the Human Interface Redirect the Blast Energy
  47. 47. IEEE Standard C37.20.7
  48. 48. IEEE Standard C37.20.7A procedure for testing and evaluatingthe performance of medium-voltagemetal-enclosed switchgear for internalarcing faults and identifying thecapabilities of the equipment relativeto specific zones of protection. NOT A DESIGN STANDARD
  49. 49. IEEE Standard C37.20.7 Arc-Resistant Definition:“Equipment designed to withstandthe effects of an internal arcingfault as indicated by successfullymeeting the requirements of IEEEStandard C37.20.7-2007.”
  50. 50. IEEE Standard C37.20.7Term Arc Resistant can be misleading.In the event of an internal arcing fault,the dangerous effects of the arc arevented away from the zone ofprotection for personnel.Term Arc Venting is more accurate
  51. 51. Arc Venting Switchgear
  52. 52. Arc Venting Switchgear48” min 95” Duct can exit to the left, right, or rear
  53. 53. Arc Venting Switchgear Exhaust Vent Duct Design Tested on the switchgear Must vent to safe area Fire rated at wall opening No external air allowed in Prevent buildup of ice and snow Prevent critter ingress
  54. 54. IEEE Standard C37.20.7“Not intended to provide this additional degree of“Intended to provide an additional degree ofprotection to operating personnel who, in thenormalprotection to the personnel performing normalperformance of their duties, would be required tooperating duties in close proximity to the equipmentopen enclosure doors or panels or otherwise alter thewhile equipment is operating under normalequipment from its normal operating conditions.”conditions”
  55. 55. IEEE Standard C37.20.7IEEE does not require that metalcladswitchgear to be manufactured topass the IEEE Standard C37.20.7Testing Procedures.
  56. 56. IEEE Standard C37.20.7 Zones of Protection
  57. 57. Zones of Protection Type 1Switchgear with arc-resistant designs orfeatures at the freelyaccessible front of theequipment only.
  58. 58. Zones of Protection Type 2Switchgear with arc-resistant designs orfeatures at the freelyaccessible exterior(front, back and sides)of the equipment only.
  59. 59. Zones of Protection Type 1BThat arcing does notcause holes in the freelyaccessible front of theenclosure or in the wallsisolating the low-voltagecontrol or instrumentcompartments.
  60. 60. Zones of Protection Type 2BThat arcing does notcause holes in the freelyaccessible front, sidesand rear of the enclosureor in the walls isolatingthe low-voltage control orinstrumentcompartments.
  61. 61. Zones of Protection Type 1BCAdds isolation fromeffects of an internalarcing fault between alladjacent compartments
  62. 62. Zones of Protection Type 2BCAdds isolation fromeffects of an internalarcing fault between alladjacent compartments
  63. 63. Arc Venting Switchgear Considerations Initial cost (up to 25% more) Need breaker lift device Must design room accordingly Must seal all cable entries Low voltage wiring protection Loss of protection if door/panel open
  64. 64. IEEE Standard C37.20.7Testing Does Not Address… Protection against toxic gases Protection against excessive sound Arcing within components Protection from above or below
  65. 65. ARC FLASH MITIGATION PEDERSEN POWER PRODUCTSTh Sign o Quality e f
  66. 66. Arc Flash Mitigation Incident Energy CalculationE =1038.7D-1.4738 x T[0.0093F2-0.3453F+5.9675]E = Incident Energy in cal/cm2D = Distance to arcing pointT = Time to clear arcing faultF = Available short circuit current
  67. 67. Arc Flash Mitigation Complete System Analysis High Speed Differential Relay Fast Bus Tripping Maintenance Relay Settings Arc Flash Detection Hi-Speed Arc Terminator 3 Cycle Breakers Current Limiting Fuses
  68. 68. Fast Bus Tripping 50/62 50 50 50 50 50T
  69. 69. Fast Bus Tripping 50/62 T 5050 50 50 50
  70. 70. Arc Flash Mitigation Complete System Analysis High Speed Bus Differential Relay Fast Bus Tripping Maintenance Relay Settings Arc Flash Detection Hi-Speed Arc Terminator 3 Cycle Breakers Current Limiting Fuses
  71. 71. Maintenance Relay SettingsRelay Group Settings Feature can be enabledby a contact input, communications or ARMsSelector Switch to enable “Maintenance Mode”protective settings when maintenance is beingperformed on the equipment.“Maintenance Mode” Protective Group settingstypically establish lower instantaneous pick-ups that can be optimized to reduce trip delaysand increase sensitivity, but avoid nuisancetrips.Remote and/or Local Visual Indication can beprovided to confirm the Relay is in MaintenanceMode. ARMs Selector Switch TB2 FP5000 Relay Maintenance Mode a b Indicating Light ARM’s Selector Switch FP5000 Postion A Position B Relay Settings Group 2 Group 1 Group Maintenance Mode Normal Mode CI - 7 Relay Contact CI - 8 CI-7 CI-8 Input
  72. 72. Arc Flash Mitigation Complete System Analysis High Speed Bus Differential Relay Fast Bus Tripping Maintenance Relay Settings Arc Flash Detection Hi-Speed Arc Terminator 3 Cycle Breakers Current Limiting Fuses
  73. 73. Arc Flash DetectionMicroprocessor based high speed relaysends trip signal to breaker upon sensinga light flash with high speed light sensorsinstalled in theswitchgearcompartments.
  74. 74. Arc Flash DetectionSEL-751A Feeder Protection RelayInstantaneous OvercurrentTimed OvercurrentInstantaneous Neutral OvercurrentTimes Neutral OvercurrentUndervoltage (Bus Side)Overvoltage (Bus Side)Undervoltage (Line Side)Overvoltage (Line Side)Over FrequencyUnder FrequencySyncronism CheckAuto-ReclosingArc-Flash DetectionArc-Flash Overcurrent
  75. 75. Arc Flash DetectionTest Cell Without Arc Flash Detection
  76. 76. Arc Flash DetectionTest Cell With Arc Flash Detection
  77. 77. Arc Flash DetectionSwitchgear Without Arc Flash Detection
  78. 78. Arc Flash DetectionSwitchgear With Arc Flash Detection
  79. 79. Arc Flash DetectionTest Dummy Without Arc Flash Detection
  80. 80. Arc Flash DetectionTest Dummy With Arc Flash Detection
  81. 81. Arc Flash Mitigation Complete System Analysis High Speed Bus Differential Relay Fast Bus Tripping Maintenance Relay Settings Arc Flash Detection Hi-Speed Arc Terminator 3 Cycle Breakers Current Limiting Fuses
  82. 82. Arc TerminatorDetects presence of an arc flash with highspeed photo sensors and closes a highspeed switch that shorts out the the mainbus in the first ¼ cycle to create a parallelpath to the arc and quickly extinguish aburning arc
  83. 83. Arc Terminator
  84. 84. Arc Terminator
  85. 85. Arc TerminatorPhase B Phase C Phase A
  86. 86. Arc TerminatorArc
  87. 87. Arc Terminator Confines Arc Effects at Initiation Point Extinguishes Arc < ¼ Cycle Prevents Pressure Buildup No Change to Relay Coordination Integrated Into Switchgear Lineup Indicates Where Flash was Detected. Limited to 40ka Symmetrical Faults
  88. 88. Arc Flash Mitigation Complete System Analysis High Speed Bus Differential Relay Fast Bus Tripping Maintenance Relay Settings Arc Flash Detection Hi-Speed Arc Terminator 3 Cycle Breakers Current Limiting Fuses
  89. 89. Arc Flash Mitigation Complete System Analysis High Speed Bus Differential Relay Fast Bus Tripping Maintenance Relay Settings Arc Flash Detection Hi-Speed Arc Terminator 3 Cycle Breakers Current Limiting Fuses
  90. 90. Current Limiting FusesCurrent Limiting Protector (CLiP)Up to 5,000A Continuous @15.5kvUp to 120,000A Interrupting
  91. 91. Current Limiting Fuses 10ka Trigger Element limits peak to 17ka vs 48ka
  92. 92. Scheme Comparison 5 Cycle Breakers 3 Cycle Breakers Arcing Percent Arcing PercentProtection Scheme Time Reduction Time ReductionNormal Coordination 800ms 0% 767ms 0%Fast Bus Trip 170ms <79%> 137ms <83%>Maintenance Settings 120ms <85%> 87ms <89%>High Speed Differential 107ms <87%> 74ms <91%>Arc Flash Detection 86ms <89%> 53ms <93%>Arc Terminator 2.3ms <99.7%> 2.3ms <99.7%>
  93. 93. NFPA Personal Protective Equipment Requirements PEDERSEN POWER PRODUCTSTh Sign o Quality e f
  94. 94. NFPA PPE RequirementsIncident Required Energy PPE Minimum Present Risk PPE Rating Protective Clothing Required to Prevent(cal/cm2) Cat (cal/cm2) Onset of a Second Degree Burn E ≤ 1.2 0 N/A Untreated Cotton1.2 < E ≤ 4 1 4 FR Shirt + FR Pants 4<E≤8 2 8 Cotton Undergarments + FR Shirt + FR Pants8 < E ≤ 25 3 25 Cotton Undergarments + FR Shirt + FR Pants + FR Coverall25 < E ≤ 40 4 40 Cotton Underwear + FR Shirt + Pants + Multi-Layer Flash Suit (minimum of 3 layers) E > 40 N/A N/A Too Dangerous to Work On
  95. 95. NFPA PPE Requirements NO CALCULATION OF INCIDENT ENERGY NFPA Table 130.7(C)(9) – 1Kv – 38Kv SwitchgearTasks Performed on Energized Equipment Risk CatInspections Outside Restricted Approach Boundary 3Operate Circuit Breaker with Door Closed 2Operate Circuit Breaker with Door Open 4Operate Meter Switch 0Work on Energized Electrical Conductors 4Work on Exposed Control Energized Circuits <120V 2Work on Exposed Control Energized Circuits >120V 4Racking of Breakers with Door Open or Closed 4Application of Safety Grounds After Voltage Test 4Remove Covers to Expose Energized Conductors 4Open Hinged Covers to Expose Energized Conductors 3Open PT or SST Compartment 4
  96. 96. NFPA PPE Requirements NO CALCULATION OF INCIDENT ENERGY NFPA Table 130.7(C)(9) – 1Kv – 38Kv Switchgear IF ARC RESISTANT SWITCHGEAR UTILIZED (for clearing times less than 500ms) Non AR AR SwgrTasks Performed on Energized Equipment Risk Cat Risk CatOperate Circuit Breaker with Door Closed 2 0Operate Circuit Breaker with Door Open 4 4Work on Energized Control Circuits <120V 2 0Work on Energized Control Circuits >120V 4 4Racking of Breakers with Door Open 4 4Racking of Breakers with Door Closed 4 0Insert or Withdraw Potential Transformers 4 0
  97. 97. E (cal/cm2) versus Fault Current5 Cycle Breaker Protection Scheme 25ka 40ka 50ka 63kaNormal Coordination 13.30 29.70 50.50 89.30Fast Bus Trip 2.83 6.32 10.73 18.97 PPE EMaintenance Settings 2.00 4.46 7.58 13.39 (cal/cm2) CatHigh Speed Differential 1.78 3.98 6.76 11.94 1.2 0Arc Flash Detection 1.47 3.20 5.43 9.60 4 13 Cycle Breaker 8 2Protection Scheme 25ka 40ka 50ka 63ka 25 3Normal Coordination 12.75 28.5 48.40 85.60 40 4Fast Bus Trip 2.28 5.09 8.65 15.29 >40 N/AMaintenance Settings 1.45 3.23 5.49 9.71High Speed Differential 1.23 2.75 4.67 8.26Arc Flash Detection 0.88 1.97 3.35 5.91
  98. 98. E (cal/cm2) versus Distance Normal Coordination (5 cycle) 100 90 PPE E 80 FC = 25ka (cal/cm2) Cat FC = 40ka 1.2 0Incident Energy (cal/cm2) 70 FC = 50ka 60 FC = 63ka 4 1 50 PPE 8 2 Cat 40 25 3 4 30 40 4 20 >40 N/A 3 10 2 0 1 0 6 12 18 24 30 36 Distance to Arcing Point (inches)
  99. 99. E (cal/cm2) versus Distance PPE Normal Coordination (5 cycle) Cat 40 PPE 35 FC = 25ka E FC = 40ka 4 (cal/cm2) Cat FC = 50ka 30 1.2 0Incident Energy (cal/cm2) FC = 63ka 25 4 1 20 3 8 2 15 25 3 10 2 40 4 5 1 >40 N/A 0 0 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 192 204 216 Distance to Arcing Point (inches) (216” = 18’)
  100. 100. E (cal/cm2) versus Distance PPE Bus Differential + Arc Flash (3 cycle) Cat 40 FC = 25ka 35 FC = 40ka 4 PPE E 30 FC = 50ka (cal/cm2) CatIncident Energy (cal/cm2) FC = 63ka 1.2 0 25 4 1 20 8 2 3 25 3 15 40 4 10 >40 N/A 2 5 1 0 0 0 6 12 18 24 30 36 Distance to Arcing Point (inches)
  101. 101. Remote Racking/Control Advantages Normal Coordination (800ms clearing time) Standard 5 cycle Breakers Fault Operation at Front Operation at 20 Feet E PPECurrent of Cubicle Door from Cubicle Door (cal/cm Cat 2) 2 25kA 8.31 cal/cm 0.51 cal/cm2 1.2 0 40kA 18.58 cal/cm2 1.13 cal/cm2 4 1 50kA 31.56 cal/cm2 1.93 cal/cm2 63kA 55.79 cal/cm2 3.40 cal/cm2 8 2 25 3 Bus Differential Protection (107ms interrupt) 40 4 Standard 5 cycle Breakers >40 N/A Fault Operation at Front Operation at 20 FeetCurrent of Cubicle Door from Cubicle Door 2 25kA 1.78 cal/cm 0.11 cal/cm2 40kA 3.98 cal/cm2 0.24 cal/cm2 50kA 6.76 cal/cm2 0.41 cal/cm2 63kA 11.94 cal/cm2 0.73 cal/cm2
  102. 102. Recommended Scheme Transformer Differential Protection Bus Differential Protection Arc Flash Detection To CT’s at Transformer 87T Zone87B Zone Arc Flash Detection Zones
  103. 103. PPP ThinkPEDERSEN

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