logging in or signing up Arc Flash -UWM kamalNashar Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 293 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: June 28, 2010 This Presentation is Public Favorites: 1 Presentation Description No description available. Comments Posting comment... By: JKRLOSS (15 month(s) ago) Very good!!! Saving..... Post Reply Close Saving..... Edit Comment Close By: matej1968 (19 month(s) ago) good Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 1: ARC FLASH D.M. Outcalt EE-771 Agenda : Agenda Arc Flash Damage Capability NEC 110.16 NFPA 70E IEEE Std. 1584 Arc Flash Calculation Steps Arc Flash Examples Issues to Consider Slide 3: A B A B BoltedShort Circuit (Rare) ArcingShort Circuit (More Common) Arc Fault Characteristics : Arc Fault Characteristics Negative volt-amp relationship. Current increases => resistance of arc decreases Voltage remains constant 60 to 140V, avg. 100V Energy confined to the arc => can do a lot of damage at the arc location Arc can travel, extending the area of damage All arcs extinguished at each sine wave zero crossing. Requires restrike voltage is 375V Arcs under 200A are unstable and generally self extinguishing Arc Flash Restrike : Arc Flash Restrike 480V Systems Have Enough Potential to Cause Restrike 208V Systems Don’t Have Enough Potential to Cause Restrike Arc Fault Damage, kW-Cycles : Arc Fault Damage, kW-Cycles Slide 7: 110.16 Flash Protection. Switchboards, panelboards, industrial control panels, and motor control centers in other than dwelling occupancies, that are likely to require examination, adjustment, servicing, or maintenance while energized, shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment. Reprinted from NEC® 2002 NEC® 2002 Article 110.16 Slide 9: Equipment Name: Slurry Pump Starter WARNING ! Arc Flash and Shock Hazard Appropriate PPE Required Slide 10: NFPA 70E Requirements for safe work practices Addresses hazards: Shock Arc Flash Requirements forshock and arc flashboundaries Requirements forpersonal protectiveequipment Incident Energy and flash boundarycalculations (<1000V, 5kA-106kA) Slide 11: IEEE Std 1584 - 2002 Addresses Arc Flash Calculations: Arcing Fault Incident energy Flash boundary Valid Ranges 208 V to 15 kV 700A to 106kA Gap 13mm to 153mm Out of Range Use Lee Equation Arcing Short Circuit : Arcing Short Circuit Pressure Waves Copper Vapor: Solid to Vapor Expands by 67,000 times Molten Metal Intense Light Hot Air-Rapid Expansion Extreme Heat 35,000 °F Shrapnel Sound Waves Arc Flash Incident : Arc Flash Incident Arcing Fault Clear Time : Arcing Fault Clear Time Arc Flash Incident : Arc Flash Incident 480 Volt System 22,600 Amp Symmetrical Fault Motor Controller Enclosure 6-Cycle Arcing Fault (0.1 sec) Slide 25: Clothed areas can be burned more severely than exposed skin Arc Flash Incident : Arc Flash Incident 480 Volt System 22,600 Amp Symmetrical Fault Motor Controller Enclosure Current Limiting Device with < ½ Cycle operation (.0083 sec). Note that Arcing Fault must be in current limiting range. Costs of Not Performing Arc Flash Studies : Costs of Not Performing Arc Flash Studies OSHA Fines Lost Productivity Medical Costs Legal Costs What Are the OSHA Regulations and NFPA 70E Requirements for Workingon “Live” Equipment? : What Are the OSHA Regulations and NFPA 70E Requirements for Workingon “Live” Equipment? Safe Work Practices : OSHA 1910.333 (a) (1) & NFPA 70E 130.1 Safe Work Practices not to work “hot” or “live” except when Employer can demonstrate: 1. De-energizing introduces additionalor increased hazards 2. Infeasible due toequipment designor operationallimitations Slide 36: Note: shock boundaries dependent on system voltage level Flash Protection Boundary (FPB) Must wear appropriate PPE FPB dependent on fault level and time duration. Equipment Incident Energy : Incident Energy Energy Per Unit of Area Received On A Surface Located A Specific Distance Away From The Electric Arc, Both Radiant And Convective, in Units of cal/cm2. Cal/cm2 : Cal/cm2 1.2 cal/cm2 - Second Degree Burn 3 cal/cm2 - 1% probability ignition of light weight cotton shirt. 4 cal/cm2 - PPE Category 1 FR Shirt & Pants 25 cal/cm2 – PPE Category 3 3 Layers Cotton Underwear, FR Shirt & Pants plus FR Coveralls. Slide 39: Highlights of changes impacting arc flash hazards PPE in the 2004 edition of NFPA 70E NFPA 70E - 2004 : NFPA 70E - 2004 Appropriate safety-related work practices shall be determined before any person approaches exposed live parts within the Limited Approach Boundary by using both shock hazard analysis and flash hazard analysis. NFPA 70E - 2004 : NFPA 70E - 2004 A flash hazard analysis shall be done in order to protect personnel from the possibility of being injured by an arc flash. The analysis shall determine the Flash Protection Boundary and the personal protective equipment that people within the Flash Protection Boundary shall use. NFPA 70E - 2004 : NFPA 70E - 2004 If live parts are not placed in an electrically safe work conditions (i.e., for the reasons of increased or additional hazards or infeasibility per 130.1) work to be performed shall be considered energized electrical work and shall be performed by written permit only. NFPA 70E : The incident energy exposure level shall be based on the working distance of the employee’s face and chest areas from a prospective arc source for the specific task to be performed. NFPA 70E NFPA 70E : Annex D: Sample Calculation of Incident Energy and Flash Protection Boundary 1) NFPA 70 Method with 100% and 38% of Bolted Fault 2) IEEE 1584 Empirical method NFPA 70E Use IEEE 1584 Calculations : Use IEEE 1584 Calculations Preliminary IEEE 1584 work used in NFPA 70E NFPA 70E equations limited to < 1000V IEEE 1584 equations expanded to 15,000V NFPA 70E 38% Arcing Fault Current is overly conservative and doesn’t guarantee worst case incident energy. Arc Flash Calculation Steps : Arc Flash Calculation Steps Determine System Modes of Operation Calculate Bolted Fault Current at each Bus Calculate Arcing Fault Current at each Bus Calculate Arcing Fault Current seen by each Protective Device Determine Trip Time for Each Protective Device based on Arcing Fault Current Calculate Incident Energy at Working Distance Calculate Arc Flash Boundary Determine Required PPE Generate Labels Bolted Fault Current : Bolted Fault Current Arcing Fault Current : Arcing Fault Current For bus voltage < 1 kV and 700A IB 106kA log (IA) = K + 0.662 log (IB) + 0.0966 V + 0.000526 G + 0.5588 V log (IB) – 0.00304 G log (IB) where log log10 IA arcing fault current K –0.153 for open configuration and –0.097 for box configuration IB bolted fault current – 3phase sym rms kA at the bus V bus voltage in kV G bus bar gap between conductors in mm For bus voltage >= 1 kV and 700A IB 106kA log (IA) =0.00402 + 0.983 log (IB) The above equations are reprinted with permission from IEEE 1584 *Copyright 2002*, by IEEE. The IEEE disclaims any responsibility or liability resulting from the placement and use in the described manner. From IEEE 1584 Copyright 2002 IEEE. All rights reserved.* Calculate Trip Time : Calculate Trip Time Identify Environment : Identify Environment Working Distance Grounded / Ungrounded Equipment Type Open Air Switchgear Panel / MCC Cable Bus Bar Gap 15kV Swgr 152mm 5kV Swgr 104mm LV Swgr 32mm Panel / MCC 25mm Cable 13mm Incident Energy : Incident Energy log (En) = K1 + K2 + 1.081 log (Ia) + 0.0011 GEn Incident energy (J/cm2) normalized for 0.2s arcing duration and 610mm working distance K1 –0.792 for open configuration –0.555 for box configuration (switchgear, panel) K2 0 for ungrounded and high resistance grounded systems -0.113 for grounded systems Ia Arcing fault current G gap between bus bar conductors in mmsolve En = 10 log En Incident Energy : Incident Energy Incident Energy convert from normalized: E = 4.184 Cf En (t/0.2) (610X / DX) E incident energy (J/cm2) Cf 1.0 for voltage above 1 kV and 1.5 for voltage at or below 1 kV t arcing duration in seconds D working distance x distance exponent x Equipment Type kV 1.473 Switchgear <= 1 1.641 Panel <= 1 0.973 Switchgear > 1 2 Cable, Open Air Flash Boundary : Flash Boundary DB arc flash boundary (mm) at incident energy of 5.0 (J/cm2) DB = [ 4.184 Cf En (t/0.2) (610X / EB) ]1/X where EB incident energy set 5.0 (J/cm2) Cf 1.0 for voltage above 1 kV and 1.5 for voltage at or below 1 kV t arcing duration in seconds x distance exponent x Equipment Type kV 1.473 Switchgear <= 1 1.641 Panel <= 1 0.973 Switchgear > 1 2 all others Find Appropriate PPE : Find Appropriate PPE Find Appropriate PPE : Find Appropriate PPE Generate Labels : Generate Labels Issues – Arc Fault Tolerance : Issues – Arc Fault Tolerance A Small Reduction in Available Fault Current can result in a large increase in incident energy due to longer trip time. Issues – Current Limiting : Issues – Current Limiting Current Limiting Range In Current Limiting Range Operates in < ½ Cycle Limits Current from 0 to >90% Limits More at Higher Currents Issues – Current Limiting : Issues – Current Limiting Ignoring Current-Limiting Effects Operates in 0.01s 2.4 Cal/cm2 at 200 kA 2.3 Cal/cm2 at 100 kA 1.2 Cal/cm2 at 50 kA Issues – Parallel Contributions : Issues – Parallel Contributions 30 kA Short Circuit Current from Utility clears in 0.5 sec. Fault Location 5 kA Short Circuit Current from Motor decays in 5 cycles (0.08 sec). Issues – Parallel Contributions : Issues – Parallel Contributions Utility + Motor for 0.08 sec Utility only for remaining 0.42 sec. Time Current Energy Accumulation (Reduction) Issues – Fault Values : Issues – Fault Values Maximum Faults used for Equipment Selection Minimum Faults Often Worst Case for Arc Flash Requires accurate utility fault contribution (not infinite source) Consider lowest pre-fault voltage Consider operating conditions with minimum motors Consider operating conditions with/without generators Consider stand-by operating modes Issues - Coordination : Issues - Coordination Coordination Traditionally used for Equipment Protection and System Reliability Arc flash requirements brings new safety focus to coordination studies looking at minimum faults and setting faster trip times. Faster trip times may cause more nuisance trips. Alternative protection schemes may gain popularity (differential protection, zone interlocking, light sensors, etc.) Issues - Faster Trip Times : Issues - Faster Trip Times Before After Issues - Faster Trip Times : Issues - Faster Trip Times Arcing Fault Minimum Tolerance Arcing Fault Maximum Tolerance Trip Time for Minimum Arcing Fault Trip Time for Maximum Arcing Fault Issues – Long Trip Times : Issues – Long Trip Times Arcing Fault Minimum Tolerance Arcing Fault Maximum Tolerance Artificial 2 second maximum arc duration Calculation Methods : Calculation Methods Hand Calculations Spreadsheets System Model Calculations Spreadsheets : Spreadsheets Advantages Inexpensive up front cost Automates Hand Calculations Disadvantages Requires manual calculation of fault currents Requires manual determination of trip times Requires manual production of labels Network Software : Network Software Advantages Performs calculations on the entire power system model. Same advantages over spreadsheet calculation such as automatic calculation of fault currents, automatic determination of protective device trip times, automatic generation of reports, custom labels, and energized work permits. Integrated with protective coordination drawings which helps evaluate alternative designs. Stores and compares multiple scenarios. Network Software : Network Software Disadvantages More expensive Requires more time and expertise to develop an accurate system model. Power*Tools Network Example : Power*Tools Network Example Sketch One-line Diagram of electrical power system in Power*Tools Software. Power*Tools Network Example : Power*Tools Network Example Enter voltage for all buses Power*Tools Network Example : Power*Tools Network Example Select type of cable from library and enter size and length for all cables. Power*Tools Network Example : Power*Tools Network Example Enter size, voltage and impedance for all transformers. Power*Tools Network Example : Power*Tools Network Example Enter available fault current from all utility sources. Power*Tools Network Example : Power*Tools Network Example Enter size and impedance for all Generators Power*Tools Network Example : Power*Tools Network Example Enter size and impedance for all Motors Power*Tools Network Example : Power*Tools Network Example Select protective devices from library and choose size and settings for each. Power*Tools Network Example : Power*Tools Network Example Run Arc Flash Calculation Power*Tools Network Example : Power*Tools Network Example View and Print Custom Labels Power*Tools Network Example : Power*Tools Network Example View and Print Energized Work Permits Power*Tools Network Example : Power*Tools Network Example Use Scenario Manager to evaluate alternative operating scenarios for the power system, including minimum and maximum fault conditions, and proposed design changes. Summary : Summary Arcing fault energy is a function of current and arc duration. Arc duration is a function of the arcing current and the protective device type and settings. NEC requires arc flash warning labels OSHA through NFPA 70E requires arc flash calculations and energized work permits. Workers are required to wear the proper PPE when inspecting and servicing equipment. You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Arc Flash -UWM kamalNashar Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 293 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: June 28, 2010 This Presentation is Public Favorites: 1 Presentation Description No description available. Comments Posting comment... By: JKRLOSS (15 month(s) ago) Very good!!! Saving..... Post Reply Close Saving..... Edit Comment Close By: matej1968 (19 month(s) ago) good Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 1: ARC FLASH D.M. Outcalt EE-771 Agenda : Agenda Arc Flash Damage Capability NEC 110.16 NFPA 70E IEEE Std. 1584 Arc Flash Calculation Steps Arc Flash Examples Issues to Consider Slide 3: A B A B BoltedShort Circuit (Rare) ArcingShort Circuit (More Common) Arc Fault Characteristics : Arc Fault Characteristics Negative volt-amp relationship. Current increases => resistance of arc decreases Voltage remains constant 60 to 140V, avg. 100V Energy confined to the arc => can do a lot of damage at the arc location Arc can travel, extending the area of damage All arcs extinguished at each sine wave zero crossing. Requires restrike voltage is 375V Arcs under 200A are unstable and generally self extinguishing Arc Flash Restrike : Arc Flash Restrike 480V Systems Have Enough Potential to Cause Restrike 208V Systems Don’t Have Enough Potential to Cause Restrike Arc Fault Damage, kW-Cycles : Arc Fault Damage, kW-Cycles Slide 7: 110.16 Flash Protection. Switchboards, panelboards, industrial control panels, and motor control centers in other than dwelling occupancies, that are likely to require examination, adjustment, servicing, or maintenance while energized, shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment. Reprinted from NEC® 2002 NEC® 2002 Article 110.16 Slide 9: Equipment Name: Slurry Pump Starter WARNING ! Arc Flash and Shock Hazard Appropriate PPE Required Slide 10: NFPA 70E Requirements for safe work practices Addresses hazards: Shock Arc Flash Requirements forshock and arc flashboundaries Requirements forpersonal protectiveequipment Incident Energy and flash boundarycalculations (<1000V, 5kA-106kA) Slide 11: IEEE Std 1584 - 2002 Addresses Arc Flash Calculations: Arcing Fault Incident energy Flash boundary Valid Ranges 208 V to 15 kV 700A to 106kA Gap 13mm to 153mm Out of Range Use Lee Equation Arcing Short Circuit : Arcing Short Circuit Pressure Waves Copper Vapor: Solid to Vapor Expands by 67,000 times Molten Metal Intense Light Hot Air-Rapid Expansion Extreme Heat 35,000 °F Shrapnel Sound Waves Arc Flash Incident : Arc Flash Incident Arcing Fault Clear Time : Arcing Fault Clear Time Arc Flash Incident : Arc Flash Incident 480 Volt System 22,600 Amp Symmetrical Fault Motor Controller Enclosure 6-Cycle Arcing Fault (0.1 sec) Slide 25: Clothed areas can be burned more severely than exposed skin Arc Flash Incident : Arc Flash Incident 480 Volt System 22,600 Amp Symmetrical Fault Motor Controller Enclosure Current Limiting Device with < ½ Cycle operation (.0083 sec). Note that Arcing Fault must be in current limiting range. Costs of Not Performing Arc Flash Studies : Costs of Not Performing Arc Flash Studies OSHA Fines Lost Productivity Medical Costs Legal Costs What Are the OSHA Regulations and NFPA 70E Requirements for Workingon “Live” Equipment? : What Are the OSHA Regulations and NFPA 70E Requirements for Workingon “Live” Equipment? Safe Work Practices : OSHA 1910.333 (a) (1) & NFPA 70E 130.1 Safe Work Practices not to work “hot” or “live” except when Employer can demonstrate: 1. De-energizing introduces additionalor increased hazards 2. Infeasible due toequipment designor operationallimitations Slide 36: Note: shock boundaries dependent on system voltage level Flash Protection Boundary (FPB) Must wear appropriate PPE FPB dependent on fault level and time duration. Equipment Incident Energy : Incident Energy Energy Per Unit of Area Received On A Surface Located A Specific Distance Away From The Electric Arc, Both Radiant And Convective, in Units of cal/cm2. Cal/cm2 : Cal/cm2 1.2 cal/cm2 - Second Degree Burn 3 cal/cm2 - 1% probability ignition of light weight cotton shirt. 4 cal/cm2 - PPE Category 1 FR Shirt & Pants 25 cal/cm2 – PPE Category 3 3 Layers Cotton Underwear, FR Shirt & Pants plus FR Coveralls. Slide 39: Highlights of changes impacting arc flash hazards PPE in the 2004 edition of NFPA 70E NFPA 70E - 2004 : NFPA 70E - 2004 Appropriate safety-related work practices shall be determined before any person approaches exposed live parts within the Limited Approach Boundary by using both shock hazard analysis and flash hazard analysis. NFPA 70E - 2004 : NFPA 70E - 2004 A flash hazard analysis shall be done in order to protect personnel from the possibility of being injured by an arc flash. The analysis shall determine the Flash Protection Boundary and the personal protective equipment that people within the Flash Protection Boundary shall use. NFPA 70E - 2004 : NFPA 70E - 2004 If live parts are not placed in an electrically safe work conditions (i.e., for the reasons of increased or additional hazards or infeasibility per 130.1) work to be performed shall be considered energized electrical work and shall be performed by written permit only. NFPA 70E : The incident energy exposure level shall be based on the working distance of the employee’s face and chest areas from a prospective arc source for the specific task to be performed. NFPA 70E NFPA 70E : Annex D: Sample Calculation of Incident Energy and Flash Protection Boundary 1) NFPA 70 Method with 100% and 38% of Bolted Fault 2) IEEE 1584 Empirical method NFPA 70E Use IEEE 1584 Calculations : Use IEEE 1584 Calculations Preliminary IEEE 1584 work used in NFPA 70E NFPA 70E equations limited to < 1000V IEEE 1584 equations expanded to 15,000V NFPA 70E 38% Arcing Fault Current is overly conservative and doesn’t guarantee worst case incident energy. Arc Flash Calculation Steps : Arc Flash Calculation Steps Determine System Modes of Operation Calculate Bolted Fault Current at each Bus Calculate Arcing Fault Current at each Bus Calculate Arcing Fault Current seen by each Protective Device Determine Trip Time for Each Protective Device based on Arcing Fault Current Calculate Incident Energy at Working Distance Calculate Arc Flash Boundary Determine Required PPE Generate Labels Bolted Fault Current : Bolted Fault Current Arcing Fault Current : Arcing Fault Current For bus voltage < 1 kV and 700A IB 106kA log (IA) = K + 0.662 log (IB) + 0.0966 V + 0.000526 G + 0.5588 V log (IB) – 0.00304 G log (IB) where log log10 IA arcing fault current K –0.153 for open configuration and –0.097 for box configuration IB bolted fault current – 3phase sym rms kA at the bus V bus voltage in kV G bus bar gap between conductors in mm For bus voltage >= 1 kV and 700A IB 106kA log (IA) =0.00402 + 0.983 log (IB) The above equations are reprinted with permission from IEEE 1584 *Copyright 2002*, by IEEE. The IEEE disclaims any responsibility or liability resulting from the placement and use in the described manner. From IEEE 1584 Copyright 2002 IEEE. All rights reserved.* Calculate Trip Time : Calculate Trip Time Identify Environment : Identify Environment Working Distance Grounded / Ungrounded Equipment Type Open Air Switchgear Panel / MCC Cable Bus Bar Gap 15kV Swgr 152mm 5kV Swgr 104mm LV Swgr 32mm Panel / MCC 25mm Cable 13mm Incident Energy : Incident Energy log (En) = K1 + K2 + 1.081 log (Ia) + 0.0011 GEn Incident energy (J/cm2) normalized for 0.2s arcing duration and 610mm working distance K1 –0.792 for open configuration –0.555 for box configuration (switchgear, panel) K2 0 for ungrounded and high resistance grounded systems -0.113 for grounded systems Ia Arcing fault current G gap between bus bar conductors in mmsolve En = 10 log En Incident Energy : Incident Energy Incident Energy convert from normalized: E = 4.184 Cf En (t/0.2) (610X / DX) E incident energy (J/cm2) Cf 1.0 for voltage above 1 kV and 1.5 for voltage at or below 1 kV t arcing duration in seconds D working distance x distance exponent x Equipment Type kV 1.473 Switchgear <= 1 1.641 Panel <= 1 0.973 Switchgear > 1 2 Cable, Open Air Flash Boundary : Flash Boundary DB arc flash boundary (mm) at incident energy of 5.0 (J/cm2) DB = [ 4.184 Cf En (t/0.2) (610X / EB) ]1/X where EB incident energy set 5.0 (J/cm2) Cf 1.0 for voltage above 1 kV and 1.5 for voltage at or below 1 kV t arcing duration in seconds x distance exponent x Equipment Type kV 1.473 Switchgear <= 1 1.641 Panel <= 1 0.973 Switchgear > 1 2 all others Find Appropriate PPE : Find Appropriate PPE Find Appropriate PPE : Find Appropriate PPE Generate Labels : Generate Labels Issues – Arc Fault Tolerance : Issues – Arc Fault Tolerance A Small Reduction in Available Fault Current can result in a large increase in incident energy due to longer trip time. Issues – Current Limiting : Issues – Current Limiting Current Limiting Range In Current Limiting Range Operates in < ½ Cycle Limits Current from 0 to >90% Limits More at Higher Currents Issues – Current Limiting : Issues – Current Limiting Ignoring Current-Limiting Effects Operates in 0.01s 2.4 Cal/cm2 at 200 kA 2.3 Cal/cm2 at 100 kA 1.2 Cal/cm2 at 50 kA Issues – Parallel Contributions : Issues – Parallel Contributions 30 kA Short Circuit Current from Utility clears in 0.5 sec. Fault Location 5 kA Short Circuit Current from Motor decays in 5 cycles (0.08 sec). Issues – Parallel Contributions : Issues – Parallel Contributions Utility + Motor for 0.08 sec Utility only for remaining 0.42 sec. Time Current Energy Accumulation (Reduction) Issues – Fault Values : Issues – Fault Values Maximum Faults used for Equipment Selection Minimum Faults Often Worst Case for Arc Flash Requires accurate utility fault contribution (not infinite source) Consider lowest pre-fault voltage Consider operating conditions with minimum motors Consider operating conditions with/without generators Consider stand-by operating modes Issues - Coordination : Issues - Coordination Coordination Traditionally used for Equipment Protection and System Reliability Arc flash requirements brings new safety focus to coordination studies looking at minimum faults and setting faster trip times. Faster trip times may cause more nuisance trips. Alternative protection schemes may gain popularity (differential protection, zone interlocking, light sensors, etc.) Issues - Faster Trip Times : Issues - Faster Trip Times Before After Issues - Faster Trip Times : Issues - Faster Trip Times Arcing Fault Minimum Tolerance Arcing Fault Maximum Tolerance Trip Time for Minimum Arcing Fault Trip Time for Maximum Arcing Fault Issues – Long Trip Times : Issues – Long Trip Times Arcing Fault Minimum Tolerance Arcing Fault Maximum Tolerance Artificial 2 second maximum arc duration Calculation Methods : Calculation Methods Hand Calculations Spreadsheets System Model Calculations Spreadsheets : Spreadsheets Advantages Inexpensive up front cost Automates Hand Calculations Disadvantages Requires manual calculation of fault currents Requires manual determination of trip times Requires manual production of labels Network Software : Network Software Advantages Performs calculations on the entire power system model. Same advantages over spreadsheet calculation such as automatic calculation of fault currents, automatic determination of protective device trip times, automatic generation of reports, custom labels, and energized work permits. Integrated with protective coordination drawings which helps evaluate alternative designs. Stores and compares multiple scenarios. Network Software : Network Software Disadvantages More expensive Requires more time and expertise to develop an accurate system model. Power*Tools Network Example : Power*Tools Network Example Sketch One-line Diagram of electrical power system in Power*Tools Software. Power*Tools Network Example : Power*Tools Network Example Enter voltage for all buses Power*Tools Network Example : Power*Tools Network Example Select type of cable from library and enter size and length for all cables. Power*Tools Network Example : Power*Tools Network Example Enter size, voltage and impedance for all transformers. Power*Tools Network Example : Power*Tools Network Example Enter available fault current from all utility sources. Power*Tools Network Example : Power*Tools Network Example Enter size and impedance for all Generators Power*Tools Network Example : Power*Tools Network Example Enter size and impedance for all Motors Power*Tools Network Example : Power*Tools Network Example Select protective devices from library and choose size and settings for each. Power*Tools Network Example : Power*Tools Network Example Run Arc Flash Calculation Power*Tools Network Example : Power*Tools Network Example View and Print Custom Labels Power*Tools Network Example : Power*Tools Network Example View and Print Energized Work Permits Power*Tools Network Example : Power*Tools Network Example Use Scenario Manager to evaluate alternative operating scenarios for the power system, including minimum and maximum fault conditions, and proposed design changes. Summary : Summary Arcing fault energy is a function of current and arc duration. Arc duration is a function of the arcing current and the protective device type and settings. NEC requires arc flash warning labels OSHA through NFPA 70E requires arc flash calculations and energized work permits. Workers are required to wear the proper PPE when inspecting and servicing equipment.