Читать книгу Arc Flash Hazard Analysis and Mitigation - J. C. Das - Страница 4

1 Chapter 1Figure 1.1. Treeing phenomena in nonself-restoring insulation, leading to ulti...Figure 1.2. The various stages of pressure buildup and its release for an arc ...Figure 1.3. Pressure versus distance from the center of the arc, based on Lee’...Figure 1.4. Peak sound pressure in dBA, at a distance of 1.8 m from a variety ...Figure 1.5. Average arcing current versus the peak sound pressure dBA. Source:...Figure 1.6. Fibrillating current (ma) rms, versus body weight. Source: Referen...Figure 1.7. Ventricular fibrillation curves, current versus time. Source: Refer...Figure 1.8. Shock hazard categories according to IEC. Figure 1.9. Hazard boundaries around an arcing source, adapted from NFPA 70E. Figure 1.10. To illustrate the arcing time for low voltage circuit breakers, a...Figure 1.11. An outfit for PPE HRC4.Figure 1.12. A specimen arc flash label.

2 Chapter 2Figure 2.1. Logo for the U.S. NIOSH PtD initiative.Figure 2.2. Key elements of safety by design.Figure 2.3. Statistics of electrical nonfatal injuries, industrywise, from 19...Figure 2.4. Fatalities in the construction industry, 1992–2002. 1: Tot...Figure 2.5. Percentage survival rate with respect to percentage body burns and...Figure 2.6. Risk and safety integrated concepts.Figure 2.7. Flow chart-risk assessment procedure.Figure 2.8. Elements of risk.Figure 2.9. Risk management process.

3 Chapter 3Figure 3.1. Electrode configurations.Figure 3.2. I_arc versus V_oc for 208–1000 V, Comparison of IEEE 2002 versus 2018.Figure 3.3. I_arc versus V_oc for 1–15 kV, Comparison of IEEE 2002 versus 2018.Figure 3.4. Flow chart for the calculation of arc flash hazard.

4 Chapter 4Figure 4.1. Methods of system grounding. Figure 4.2. Arc fault in a 3/16″ gap, 480-V system.Figure 4.3. Overvoltage versus ratio of resistor kW/charging kVA.Figure 4.4. (a and b) The stray capacitance currents and voltages in a low vol...Figure 4.5. (a) Selective ground fault protection in a high resistance grounde...Figure 4.6. (a) Corner grounded delta grounded system; (b) mid-point grounded ...Figure 4.7. (a) Zigzag grounding transformer showing winding connections, curr...Figure 4.8. Methods of low resistance or high resistance grounding of neutrals...Figure 4.9. A solidly grounded distribution system for selective ground fault ...Figure 4.10. A three-step ground fault coordination of the distribution system...Figure 4.11. Phase fault coordination of the system of Figure 4.9.Figure 4.12. Ground fault protection coordination with superimposed phase faul...Figure 4.13. Distribution system in Figure 4.9, modified for improved selective...Figure 4.14. Ground fault coordination, with low ground fault pickup settings ...Figure 4.15. A medium voltage low resistance grounded distribution system for ...Figure 4.16. Selective ground fault coordination of system in Figure 4.15, ext...Figure 4.17. Ground fault coordination in a large interconnected 13.8-kV syste...Figure 4.18. Selective ground fault coordination for the 13.8-kV distribution ...Figure 4.19. Derivation of a zero sequence polarizing voltage for directional ...

5 Chapter 5Figure 5.1. Decaying AC and DC components of the short-circuit current and the...Figure 5.2. Equivalent machine model for short-circuit calculations.Figure 5.3. Multiplying factors for E/X or E/Z amperes, three-phase faults, fo...Figure 5.4. (a) Typical computer-based calculation results, momentary (first cy...Figure 5.5. A low voltage distribution system for calculations of short-circui...Figure 5.6. Equivalent network for a fault at bus 3 (Figure 5.5 and Example 5....Figure 5.7. Equivalent network for a fault at bus 2 (see Figure 5.5 and Exampl...Figure 5.8. A multivoltage distribution system for hand calculations of short-...Figure 5.9. Equivalent network for a fault at 13.8 kV bus 2 (see Example 5.2).Figure 5.10. (a) Line-to-ground fault in a three-phase system, (b) line-to-gro...Figure 5.11. (a) Double line-to-ground fault in a three-phase system, (b) doub...Figure 5.12. (a) Two-phase fault in a three-phase system, (b) Two-phase fault-...Figure 5.13. Equivalent zero sequence circuit for a fault on bus 2 (Example 5....Figure 5.14. (a) Equivalent zero sequence circuit of a transformer with primar...Figure 5.15. Equivalent admittance diagram of the system in Figure 5.5.

6 Chapter 6Figure 6.1. Time constant of exponential DC decaying component of the short-ci...Figure 6.2. (a) Short-circuit current profile utility source only, no generator...Figure 6.3. Equivalent transformer circuits of a synchronous generator during ...Figure 6.4. Decaying AC component of the short-circuit current showing subtran...Figure 6.5. Calculated fault decrement curve of generator (DC component not sh...Figure 6.6. Calculated short-circuit currents for terminal fault of a 900 hp, ...Figure 6.7. A 13.8 kV bus with multiple sources of short-circuit currents.Figure 6.8. (a–c) Accumulation of incident energy profiles (see text).Figure 6.9. Calculation of short-circuit current decay profiles at 13.8 kV bus ...Figure 6.10. Crowbar arrangement.

7 Chapter 7Figure 7.1. Functionality of a MMPR (multifunction microprocessor-based relay)...Figure 7.2. An electromechanical overcurrent relay. Source: IEEE standard 141-...Figure 7.3. Time–current inverse characteristics of various overcurrent relay ...Figure 7.4. Instantaneous overcurrent function logic in an MMPR.Figure 7.5. Time–overcurrent characteristics of various overcurrent relay type...Figure 7.6. A low voltage system for illustration of selection of transformer ...Figure 7.7. Time–current coordination plot related to Figure 7.6, Example 7.2.Figure 7.8. A bimetallic thermal trip device. (a) Normal state and (b) tripped...Figure 7.9. A magnetic instantaneous trip device. (a) Normal state and (b) tri...Figure 7.10. (a) Current limitation, operation of a current limiting MCCB; (b)...Figure 7.11. Operation of a MCCB, not specifically designated as current limiti...Figure 7.12. Let-through characteristics of a current limiting MCCB.Figure 7.13. Time–current characteristics of a modern low voltage electronic t...Figure 7.14. Low arc flash circuit breaker design. Source: Arc-Flash Protection...Figure 7.15. Short-time bands of a low voltage trip programmer, to show coordi...Figure 7.16. A low voltage double-ended substation for calculations of arc flas...Figure 7.17. Let-through characteristics of a current-limiting fuse.Figure 7.18. Example of an installation where the motor contribution exceeds N...Figure 7.19. Current interruption by a current-limiting fuse.Figure 7.20. Arc voltage generated by a current limiting fuse during interrupt...Figure 7.21. Relation of X/R to rms and peak multiplying factors. Source: Base...Figure 7.22. Low voltage distribution system with integrally fused main second...Figure 7.23. Coordination in the distribution system of Figure 7.22. Current l...Figure 7.24. Coordination in the distribution system of Figure 7.22, modified b...Figure 7.25. Variations in the time–current characteristics of 150-A class E f...Figure 7.26. Thermal withstand curve of a 2.4-kV, 400-hp, SF = 1.15 motor.Figure 7.27. (a) and (b) Protection of thermal withstand curve of the motor in...Figure 7.28. Premature trip of 400-hp motor with overcurrent setting in Figure...Figure 7.29. A two-step overcurrent relay characteristics and motor starting c...Figure 7.30. Application of a zero-speed switch and an overcurrent element for...Figure 7.31. A practical time–current coordination of a 2.3-kV, 1000-hp motor ...Figure 7.32. A parallel running 10 MVA generator with a utility source for app...Figure 7.33. 51-V relay settings and coordination of the generator for the con...

8 Chapter 8Figure 8.1. A 13.8-kV sectionalized bus with overlapping zones of differential...Figure 8.2. A 13.8-kV bus provided with only bus differential protection. The ...Figure 8.3. A cross-section through two high metal-clad switchgear, with bus d...Figure 8.4. (a) Overlapping zones of differential protection provided by prope...Figure 8.5. Concepts of differential protection. (a) A fault external to the p...Figure 8.6. (a) A differential protection using a simple overcurrent relay; (b...Figure 8.7. (a) Principle of a percent differential relay, (b) fixed percentage...Figure 8.8. Principle of a high impedance bus differential relay.Figure 8.9. Equivalent circuit of a bus differential relay for an external fau...Figure 8.10. Connections of a three-phase differential relay.Figure 8.11. Block circuit diagram of a modern multi-function, microprocessor ...Figure 8.12. Two-slope characteristics of the relay in Figure 8.11, with low a...Figure 8.13 (a) Directional operating principle during external faults; (b) di...Figure 8.14. Principle of CT saturation detection in Figure 8.11.Figure 8.15. Output logic of biased differential protection, Figure 8.11.Figure 8.16. Illustrates severe CT saturation of a CT during external fault.Figure 8.17. Differential protection of a 40-MVA, wye–delta connected, 138–13....Figure 8.18. A two-slope restraint characteristics of a modern transformer dif...Figure 8.19. (a) Phase shifts in two-winding transformers; (b) phase shifts in...Figure 8.20. Transformer winding phase-shift correction matrices, CTs on both ...Figure 8.21. A block circuit diagram of a modern transformer differential rela...Figure 8.22. A pilot wire scheme using metallic pilots and electromechanical r...Figure 8.23. The details of the equipment at one end of a pilot wire protectio...Figure 8.24. Simplified architecture of modern line current differential system...Figure 8.25. Alpha plane characteristics of a differential relay described by ...Figure 8.26. Characteristics of a new differential scheme in the alpha-plane.Figure 8.27. Typical operating times of differential and arc flash detection (A...

9 Chapter 9Figure 9.1. Arc brightness verses time after a 20-kA arc flash event.Figure 9.2. Relative sensitivity of a lens sensor from different angles of lig...Figure 9.3. Sensitivity of sensors at various compensation settings. Source: C...Figure 9.4. (a) and (b) A lens or point sensor; (c) a fiber sensor.Figure 9.5. Layout of fiber sensor in switchgear, showing minimum bending radiu...Figure 9.6. (a and b) Routing of fibers through bus compartment, breaker compar...Figure 9.7. (a) Routing of fiber for nonselective AFD protection; (b) routing o...Figure 9.8. A logic circuit diagram of AFD system.Figure 9.9. AFD with current supervision, operating time of output 2.5 ms or l...Figure 9.10. Transfer of arc from the equipment to a remotely located location...Figure 9.11. A cross-section through the arc vault—arc containment device.Figure 9.12. Arc vault, sensing and control system for system protected with t...Figure 9.13. Arc vault located remotely in a separate cubicle. Source: Courtes...

10 Chapter 10Figure 10.1. Settings on curve flexures, which can give increased fault clearan...Figure 10.2. Selectivity criteria based upon I²t let-through of current-limiti...Figure 10.3. I²t let-through curves of medium voltage power fuses, 4–40 A, of ...Figure 10.4. Peak let-through current of time-delay RK5 fuses of a manufacture...Figure 10.5. Coordination on instantaneous basis between an upstream LVPCB and...Figure 10.6. Graphical construction for determining the peak current setting o...Figure 10.7. Coordination on instantaneous basis between an upstream LVPCB and...Figure 10.8. To illustrate selective settings with various sensing methods: TC...Figure 10.9. Peak let-through current of current-limiting 100 A MCCB.Figure 10.10. An essential service system configuration for full selectivity an...Figure 10.11. Time–current coordination of the OCPDs in Figure 10.10.Figure 10.12. Time–current coordination of the OCPDs in Figure 10.10.Figure 10.13. Time–current coordination of the OCPDs in Figure 10.10.Figure 10.14. A medium voltage distribution system for selective overcurrent c...Figure 10.15. Time–current coordination in Figure 10.14, showing close spacing...Figure 10.16. Time–current coordination achieved by omitting the 5 MVA transfo...Figure 10.17. Time–current coordination for 25 MVA main transformer (Figure 10...

11 Chapter 11Figure 11.1. Faults in the secondary zone shown in solid block cleared by prim...Figure 11.2. (a) A radial system of distribution, (b) primary selective system...Figure 11.3. ANSI through fault withstand curve, category I transformers, liqu...Figure 11.4. ANSI through fault withstand curve, category II transformers: (a)...Figure 11.5. ANSI through fault withstand curve, category III transformers: (a...Figure 11.6. ANSI through fault withstand curve, category IV transformers, liq...Figure 11.7. ANSI through fault withstand curve, category I, dry-type transfor...Figure 11.8. ANSI through fault withstand curve, category II, dry type transfo...Figure 11.9. Analytical construction of a through fault curve.Figure 11.10. Variations in the total clearing time–current characteristics of...Figure 11.11. Line and winding currents in transformers for various secondary ...Figure 11.12. Through fault withstand curve protection of a 2500-kVA, Z = 5.75...Figure 11.13. Through fault withstand curve protection of a 2500-kVA, Z = 5.75...Figure 11.14. Less flammable liquid-immersed transformers compliance to NEC sec...Figure 11.15. Less flammable liquid immersed transformers compliance to NEC sec...Figure 11.16. A low voltage and medium voltage distribution system for protect...Figure 11.17. Time–current coordination plot for 480-V, 2000-kVA transformer p...Figure 11.18. Time–current coordination plot for 2.4-kV, 7500-kVA transformer ...Figure 11.19. Modified distribution system of Figure 11.16, for arc flash reduct...Figure 11.20. Time–current coordination plot for 480-V, 2000-kVA transformer p...Figure 11.21. Time–current coordination plot for 2.4-kV, 7500-kVA transformer ...Figure 11.22. Time–current coordination plot for 480-V, 2000 kVA transformer p...Figure 11.23. Time–current coordination plot for 2.4-kV, 7500-kVA transformer ...Figure 11.24. A microprocessor based overcurrent relay connected through CTs o...

12 Chapter 12Figure 12.1. Excitation characteristics of C-type current transformers, showin...Figure 12.2. Excitation characteristics of T-type current transformers.Figure 12.3. Construction of various CT types: (a) window-type CT, (b) a fully...Figure 12.4. Excitation characteristics of a 100/5 core balance CT. V_k is the ...Figure 12.5. Phase diagram of a class C current transformer.Figure 12.6. Illustrates the composite error according to IEC standards.Figure 12.7. Location of window type CTs in metal-clad draw-out switchgear. Tw...Figure 12.8. (a) Subtractive polarity and (b) additive polarity, shown by dark...Figure 12.9. (a) Residual connection of a GR fault relay through auxiliary wou...Figure 12.10. Connections of a product-type electromechanical ground fault rel...Figure 12.11. (a) Connection of a single 600/5 ratio CT, secondary voltage 162...Figure 12.12. Oscillogram showing progressive saturation of a CT.Figure 12.13. Hysteresis loop on magnetization of a magnetic material.Figure 12.14. Output of a 100/5 ratio C50 CT for a 40-kA fault current, severe...Figure 12.15. Improved response for 40 kA fault current, 200/5 ratio, C100 CT ...Figure 12.16. Adaptive overcurrent element block circuit diagram showing bipol...

13 Chapter 13Figure 13.1. Time–current characteristics of four low voltage devices for anal...Figure 13.2. Calculated incident energy release versus three-phase bolted shor...Figure 13.3. A typical indicator frame used in arc-resistance testing.Figure 13.4. Pressure buildup after an arc flash event, with and without ventin...Figure 13.5. Flap plates on an arc-resistant equipment, normally closed.Figure 13.6. Hinged arc panels with inner shield.Figure 13.7. Pressure relief plate after an arc flash event.Figure 13.8. Typical arc-resistant medium voltage enclosure with arc chimneys....Figure 13.9. Typical arc-resistant medium voltage enclosure with plenum. Sourc...Figure 13.10. Inappropriate design of external arc venting system.

14 Chapter 14Figure 14.1. Statistical data of arc flash hazard with respect to voltage level...Figure 14.2. Incident energy release verses percentage of buses, all voltages....Figure 14.3. Zone interlocking between feeder and main secondary circuit break...Figure 14.4. Zone interlocking between feeder and main secondary circuit break...Figure 14.5. A low voltage distribution system for study of zone interlocking.Figure 14.6. Time–current coordination of devices in Figure 14.5, with and wit...Figure 14.7. A low voltage distribution system, with considerable rotating mot...Figure 14.8. Time–current coordination of devices in Figure 14.7, showing moto...Figure 14.9. Zone interlocking in medium voltage system with two sources of po...Figure 14.10. Instantaneous values of short-circuit wave forms from three sour...Figure 14.11. (a) Location of a fault through sensing the fault current direct...Figure 14.12. A block circuit diagram of microprocessor-based low voltage swit...Figure 14.13. A low voltage distribution system with provision of 1000-A class...Figure 14.14. Time–current coordination of the devices in Figure 14.13, withou...Figure 14.15. Time–current coordination of the devices in Figure 14.13, with 1...Figure 14.16. Picture of a voltage indicator mounted on a low voltage MCC door...Figure 14.17. Portable remote racking system for low voltage MCC buckets.Figure 14.18. Another version of a portable remote racking system for low volt...Figure 14.19. Picture of a low voltage MCC bucket, showing safety shutter posi...Figure 14.20. A control circuit diagram for connections of maintenance mode sw...Figure 14.21. Arc fault resistance infrared sight glass.Figure 14.22. Field of view of an infrared window equal to six times the cabin...Figure 14.23. A combination of viewing window and infrared window.Figure 14.24. Assembly of a TCL (also called FCL).Figure 14.25. Schematic diagram of a TCL.Figure 14.26. The timing diagram of a TCL with magnitude sensing.Figure 14.27. Arresting the system voltage dip with TCL.Figure 14.28. (a) TCL used in a reactor bypass scheme; (b) time–current profil...Figure 14.29. Normalized NQN and PDI (see text).Figure 14.30. PD measurement data of a generator over the course of years.Figure 14.31. CSA (current signal analysis) of a rotating machine showing brea...Figure 14.32. Model of a leaky dielectric and loss angle (see text).

15 Chapter 15Figure 15.1. Short-circuit profile of various DC sources: (a) rectifier with a...Figure 15.2. Standard approximation of short-circuit function. Source: Referen...Figure 15.3. A DC distribution system for calculation of short-circuit current...Figure 15.4. Equivalent circuit of short circuit of a battery through external...Figure 15.5. Time to peak t_pk and rise time constant τ_1B for the short-circuit...Figure 15.6. Layout of a battery system for calculation of short-circuit curre...Figure 15.7. Calculated short-circuit time–current profiles: (a) battery, (b) ...Figure 15.8. Factors κ_1M and κ_2M for determining the time to peak t_pM and the ...Figure 15.9. Short-circuit current profile of a rectifier.Figure 15.10. Equivalent circuit for the short-circuit current calculation of ...Figure 15.11. Total short-circuit current profile of four partial short-circui...Figure 15.12. (a) Minimum arc voltage for vertical arcs; (b) minimum arc volta...Figure 15.13. A simplified model of arcing in a DC system.Figure 15.14. Arcing current profile superimposed on the short-circuit current...Figure 15.15. Time–current characteristics of a class L, 1000-A fuse.Figure 15.16. Calculated short-circuit and arcing current profiles (see Exampl...Figure 15.17. Short-circuit current of a converter with grid (gate) control. S...

16 Chapter 16Figure 16.1. Power station substation automation (SA) functional diagram.Figure 16.2. IEC 61850 communication profiles.Figure 16.3. Hierarchy of IEC 61850 data model.Figure 16.4. Circuit breaker Model-XCBR information tree.Figure 16.5. Anatomy of IEC 61850 object nomenclature.Figure 16.6. GOOSE messaging.Figure 16.7. (a) Fiber optic multimode cable cross-section and light transmi...Figure 16.8. (a) Redundant star architecture using redundant ports on IEDs; ...Figure 16.9. A schematic picture of substation layouts and connections in a ...

17 Appendix AFigure A.1. Illustration of (a) positive and (b) negative skewness. (c) Illu...Figure A.2. Gaussian or normal distribution graph of the density function.Figure A.3. Criteria of fitting a least square line in a scatter plot.