arc-flash analysis of utility power systems - Michigan Technological ...

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Abstract The electric utility business is an inherently dangerous area to work in with employees exposed to many potential hazards daily. One such hazard is an arc flash. An arc flash is a rapid release of energy, referred to as incident energy, caused by an electric arc. Due to the random nature and occurrence of an arc flash, one can only prepare and minimize the extent of harm to themself, other employees and damage to equipment due to such a violent event. Effective January 1, 2009 the National Electric Safety Code (NESC) requires that an arc-flash assessment be performed by companies whose employees work on or near energized equipment to determine the potential exposure to an electric arc. To comply with the NESC requirement, Minnesota Power’s (MP’s) current short circuit and relay coordination software package, ASPEN OneLiner TM and one of the first software packages to implement an arc-flash module, is used to conduct an arc-flash hazard analysis. At the same time, the package is benchmarked against equations provided in the IEEE Std. 1584-2002 and ultimately used to determine the incident energy levels on the MP transmission system. This report goes into the depth of the history of arc-flash hazards, analysis methods, both software and empirical derived equations, issues of concern with calculation methods and the work conducted at MP. This work also produced two offline software products to conduct and verify an offline arc-flash hazard analysis. viii
Chapter 1: Introduction Electric utility equipment, like any other product we use in everyday activities, is prone to failure and requires preventative maintenance and repair. During these maintenance activities, employees become exposed to a potential arc-flash incident. An arc-flash incident is a violent event exposing employees to not only high temperatures and noise levels but also shrapnel from the equipment involved in the arc flash. This incident may be caused by the employee themselves or by a random equipment failure on nearby equipment. Effective January 1 st , 2009 NESC requires that an arc-flash assessment be performed by companies whose employees work on or near energized equipment to determine the potential exposure to an electric arc employers are. For this reason detailed research has been conducted on the behavior of arc flashes and emperical equations have been developed to predict the energy released during the event and IEEE Std. 1584-2002 enforces the equations. Figure 1.1 below captures what an employee may experience if subjected to an arc-flash incident [1]. Figure 1.1: Lab demonstration of arc-flash explosion 1
Page 1 and 2: ARC-FLASH ANALYSIS OF UTILITY POWER
Page 3 and 4: Table of Contents Table of Contents
Page 5 and 6: List of Figures Figure 1.1: Lab dem
Page 7: Acknowledgements I would like to th
Page 11 and 12: 2, by using tables developed by the
Page 13 and 14: If the assessment reveals that the
Page 15 and 16: distance, I 2 t/d 3 , isn’t clear
Page 17 and 18: (subscript 1), one of moderate leng
Page 19 and 20: equations are used to calculate the
Page 21 and 22: By raising 10 to the power of l g E
Page 23 and 24: 3.3 National Electrical Safety Code
Page 25 and 26: Table 3.3: Live-line tool work PPE
Page 27 and 28: Figure 3.2: ASPEN® arc-flash calcu
Page 29 and 30: After the verification of the MATLA
Page 31 and 32: Figure 4.1: Example system oneline
Page 33 and 34: An evaluation of this condition was
Page 35 and 36: Figure 4.4: Incident energy using e
Page 37 and 38: Figure 4.6: Incident energy based o
Page 39 and 40: Figure 4.8: Incident energy followi
Page 41 and 42: Special consideration needs to be t
Page 43 and 44: Figure 4.11: Potential incident ene
Page 45 and 46: Chapter 5: Mitigation Methods and H
Page 47 and 48: Chapter 6: Conclusions and Recommen
Page 49 and 50: • Perform a full system analysis
Page 51 and 52: Appendix A Procedure for Arc-Flash
Page 53 and 54: Appendix B Arc-Flash Analyzer Verif
Page 55 and 56: elow System Voltage Fault Current A
Page 57 and 58: % Update handles structure guidata(
Page 59 and 60:
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Page 61 and 62:
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Page 63 and 64:
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C.1 System Online Diagram Appendix
Page 67 and 68:
C.5 Relay Data Table C.4: Example s
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Bus = Bus 3 138kV Equipment categor
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Breaker interrupting time (cycles)
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D.2 PPE Levels Required Substation
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Breaker interrupting time (cycles)
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Interrupting device = [OC relay] Sy
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Appendix F Energy Plot Data Table F
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87 0.090393103 0.36157241 0.9039310
Page 83 and 84:
2.722222222 45.4311525 181.7246 454
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5.277777778 170.767831 683.0713 170
Page 87 and 88:
7.833333333 376.180721 1504.723 376
Page 89 and 90:
10.38888889 661.669821 2646.679 661
Page 91 and 92:
12.94444444 1027.23513 4108.941 102
Page 93 and 94:
2.138888889 12.2298446 48.91938 122
Page 95 and 96:
4.694444444 28.1962506 112.785 281.
Page 97 and 98:
7.25 44.7470866 178.9883 447.4709 9
Page 99 and 100:
9.805555556 61.6752248 246.7009 616
Page 101 and 102:
12.36111111 78.8850842 315.5403 788
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