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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Serie: IEEE Press Series on Power Engineering
- Sprache: Englisch
Energy Production Systems Engineering presents IEEE, Electrical Apparatus Service Association (EASA), and International Electrotechnical Commission (IEC) standards of engineering systems and equipment in utility electric generation stations.
- Includes fundamental combustion reaction equations
- Provides methods for measuring radioactivity and exposure limits
- Includes IEEE, American Petroleum Institute (API), and National Electrical Manufacturers Association (NEMA) standards for motor applications
- Introduces the IEEE C37 series of standards, which describe the proper selections and applications of switchgear
- Describes how to use IEEE 80 to calculate the touch and step potential of a ground grid design
This book enables engineers and students to acquire through study the pragmatic knowledge and skills in the field that could take years to acquire through experience alone.
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IEEE Press445 Hoes LanePiscataway, NJ 08854
IEEE Press Editorial BoardTariq Samad, Editor in Chief
George W. Arnold
Xiaoou Li
Ray Perez
Giancarlo Fortino
Vladimir Lumelsky
Linda Shafer
Dmitry Goldgof
Pui-In Mak
Zidong Wang
Ekram Hossain
Jeffrey Nanzer
MengChu Zhou
ENERGY PRODUCTIONSYSTEMS ENGINEERING
THOMAS H. BLAIR
Tampa Electric Company and University of South Florida
Copyright © 2017 by The Institute of Electrical and Electronics Engineers, Inc.
Published by John Wiley & Sons, Inc., Hoboken, New Jersey. All rights reservedPublished simultaneously in Canada
No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permission.
Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.
For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002.
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com.
Library of Congress Cataloging-in-Publication Data is available.
ISBN: 978-1-119-23800-3
Dedicated to the memory ofProfessor Joseph Peter SkalaAdjunct Professor at USF and St. Petersburg Junior Collegefor your support and encouragement to your many students.
CONTENTS
LIST OF FIGURES
LIST OF TABLES
LIST OF ANNEX
ACKNOWLEDGMENTS
INTRODUCTION
CHAPTER 1
ELECTRICAL SAFETY
Installation Safety Requirements—General Industry (NEC®)
Installation Safety Requirements—Special Industry – Utility (NESC)
Safe Work Practice Requirements
Electrical PPE
ARC Flash Analysis Utilizing NFPA 70E Tables
Hazardous/Classified Areas
Classified Area – “Class” System
Classified Area – “Zone” System
Boiler Control and Burner Management
Glossary of Terms
Problems
Recommended Reading
CHAPTER 2
BASIC THERMAL CYCLES
Steam Thermodynamic Analysis Fundamentals
Pressure, Temperature, and Volume Relationships
Heat Rate
Gas Thermodynamic Analysis Fundamentals
Glossary of Terms
Problems
Recommended Reading
CHAPTER 3
BOILERS AND STEAM GENERATORS
Air Preheater
Cooling Towers
Glossary of Terms
Problems
Recommended Reading
CHAPTER 4
FOSSIL FUELS AND THE BASIC COMBUSTION PROCESS
Combustible Fuel
Oxygen
Fossil Fuels
Natural Gas
Fuel Oil
Glossary of Terms
Problems
Recommended Reading
CHAPTER 5
HYDRAULIC TURBINES
Hydraulic Reaction Turbines
Hydraulic Impulse Turbines
Kinetic Energy Hydraulic Turbines
Glossary of Terms
Problems
Recommended Reading
CHAPTER 6
NUCLEAR POWER
Boiling Water Reactor
Pressurized Water Reactor
Pressurized Heavy Water Reactor
Pressure Tube Graphite Reactor
High Temperature Gas-Cooled Reactor
Liquid Metal Fast Breeder Reactor
Nuclear Power Safety
Units of Activity
Units of Exposure
Glossary of Terms
Problems
Recommended Reading
CHAPTER 7
CONVEYORS
Belt Conveyor
Pneumatic Conveyor Systems
Rotary Screw Conveyor System
Vibrating Conveyor System
Conveyor Safety
Glossary of Terms
Problems
Recommended Reading
CHAPTER 8
FANS
Centrifugal Fan (Radial Airflow)
Axial Fan (Axial Airflow)
Centrifugal Fan Fundamental Laws
Glossary of Terms
Problems
Recommended Reading
CHAPTER 9
PUMPS
System Resistance Curves
Centrifugal Pump
Axial Flow Pump
Positive Displacement Pump
Glossary of Terms
Problems
Recommended Reading
CHAPTER 10
CONDENSER COOLING SYSTEM
Condenser Cooling
Condenser Operation
Condenser Safety Precautions
Glossary of Terms
Problems
Recommended Reading
CHAPTER 11
STEAM TURBINES
Turbine Safety
Turbine Vibration
Glossary of Terms
Problems
Recommended Reading
CHAPTER 12
GAS TURBINES
Glossary of Terms
Problems
Recommended Reading
CHAPTER 13
RECIPROCATING ENGINES
Glossary of Terms
Problems
Recommended Reading
CHAPTER 14
ELECTRICAL SYSTEM
Distribution System Configuration
Enclosures
Busway Applications
Cables
Cable Testing
Megger Testing
High Potential Testing
Acceptance
Cathodic Protection
Glossary of Terms
Problems
Recommended Reading
CHAPTER 15
TRANSFORMERS AND REACTORS
Glossary of Terms
Problems
Recommended Reading
CHAPTER 16
GENERATORS
Generator Protection
Glossary of Terms
Problems
Recommended Reading
CHAPTER 17
MOTORS
Reduced Voltage Starting Methods
Glossary of Terms
Problems
Recommended Reading
CHAPTER 18
VARIABLEFREQUENCY DRIVESYSTEMS
Harmonics
Glossary of Terms
Problems
Recommended Reading
CHAPTER 19
SWITCHGEAR
Glossary of Terms
Problems
Recommended Reading
CHAPTER 20
BATTERY/VITAL BUS SYSTEMS
Design of Battery Systems (DC System Load and Battery Capacity)
Design of Battery Systems (Battery Charger)
Glossary of Terms
Problems
Recommended Reading
CHAPTER 21
GROUND SYSTEM
Ungrounded System
Resistance Grounded System
Reactance Grounded System
Solidly Grounded System
Glossary of Terms
Problems
Recommended Reading
CHAPTER 22
ELECTRICAL SYSTEM PROTECTION AND COORDINATION
Glossary of Terms
Problems
Recommended Reading
CHAPTER 23
CONTROL SYSTEMS
Glossary of Terms
Problems
Recommended Reading
CHAPTER 24
INSTRUMENTS AND METERS
Temperature
Flow
Pressure
Level
Instrument Identification Standards
Glossary of Terms
Problems
Recommended Reading
CHAPTER 25
VALVES AND ACTUATORS
Valve Types
Ball Valve
Check Valve
Gate Valve
Globe Valve
Relief Valve
Valve Losses
Glossary of Terms
Problems
Recommended Reading
CHAPTER 26
EMISSION CONTROL SYSTEMS
Particulate Emission Control
Nitrogen Oxides Emissions Control
Combustion Control of No
x
Post-Combustion Control of NO
x
Sulfur Dioxide Emissions Control (Scrubber)
Continuous Emission Monitoring System (CEMS)
Carbon Dioxide (CO
2
) and Greenhouse Gas Emission Control
Glossary of Terms
Problems
Recommended Reading
CHAPTER 27
WATER TREATMENT
Flow
Areas and Volumes
Volume
Detention Time
Dosage
Process Removal Efficiency
Pump Calculations
Glossary of Terms
Problems
Recommended Reading
CHAPTER 28
SOLAR AND WIND ENERGY
Wind Energy
Thermal Solar Energy
Parabolic Trough Solar Field Technology
Solar Power Towers
Dish System
Photovoltaic Solar Energy
Glossary of Terms
Problems
Recommended Reading
ANNEXES
INDEX
LIST OF FIGURES
1.1
Appendix A-1 – Application of 1910.269 and 1910 Subpart S to Electrical Installations.
1.2
Appendix A-2 – Application of 1910.269 and 1910 Subpart S to Electrical Safety-Related Work Practices.
1.3
Safety clearance to electric supply station fences.
1.4
Photo of load termination compartment in typical medium voltage switchgear.
1.5
Photo of typical shock protection PPE.
1.6
Photo of typical arc flash protection PPE.
1.7
Typical insulated tools.
1.8
Decision matrix if a task requires arc flash PPE.
1.9
NFPA 497 Table 5.9.2 (a) – Leakage located outdoors, at grade. The material being handled could be a flammable liquid, a liquefied or compressed flammable gas, or a flammable cryogenic liquid.
1.10
Figure 4.8(a) from NFPA 499 – Group F or Group G Dust – Indoor, Unrestricted Area; Open or Semi-Enclosed Operating Equipment.
2.1
T-s diagram for water.
2.2
Basic flow diagram for equipment thermodynamic performance evaluation.
2.3
Basic thermodynamic cycle.
2.4
Basic Carnot cycle.
2.5
Basic Rankine cycle showing operation in subcooled region for pumps.
2.6
Feedwater regenerative cycle.
2.7
Feedwater regenerative T-s diagram.
2.8
Superheat design.
2.9
Feedwater regenerative cycle with reheat.
2.10
Feedwater regenerative cycle with reheat T-s diagram.
2.11
Typical steam turbine thermodynamic cycle equipment
2.12
T-Diagram for isentropic Brayton cycle.
2.13
Brayton cycle.
2.14
T-s Diagram for isentropic and non-isentropic Brayton cycle.
3.1
Typical feedwater heater arrangement.
3.2
DCA temperature vs. shell liquid level.
3.3
Basic steam flow path.
3.4
Typical temperature profile for a heat recovery steam generator (HRSG).
3.5
Reduction of boiler efficiency due to excess air.
3.6
Photo of burner front area with boiler wall removed and water wall tubes exposed.
3.7
Secondary air damper before installation.
3.8
Tangentially fired furnace.
3.9
Coal dryer/crusher.
3.10
Ball mill coal pulverizer.
3.11
Coal classifier.
3.12
Vertical spindle coal mill arrangement.
3.13
Vertical spindle coal mill roll assembly.
3.14
Chart of dry bulb temperature to wet bulb temperature
4.1
Fire triangle.
4.2
Estimated US energy usage for 2013.
4.3
Integrated gasification combined cycle (IGCC) process.
5.1
Typical kinetic energy conversion devices.
6.1
Radioactive decay in terms of half-life.
6.2
Typical boiling water reactor (BWR) arrangement.
6.3
Typical pressurized water reactor (PWR) arrangement.
6.4
Reactor emergency core cooling system.
6.5
Reactor post-accident heat removal system.
6.6
Reactor post-accident radioactivity removal system.
7.1
Simplified belt conveyor arrangement with different diameters.
7.2
Simplified belt conveyor arrangement with same diameters.
7.3
Typical tripper arrangement.
8.1
Types of centrifugal fan blade designs.
8.2
Chart showing fan system curve for three system resistance values that depend on damper position with constant fan speed.
8.3
Power for operating points A, B, and C.
8.4
Chart showing fan system curve for three fan speeds with constant system resistance utilizing fan speed for control.
8.5
Power for operating points A, D, and E.
9.1
Pump system resistance with zero differential head and no throttling.
9.2
Pump system resistance with zero differential head and throttling.
9.3
Pump system resistance with non-zero differential head and throttling.
9.4
Pump system operating point.
9.5
Pump flow control utilizing pump speed.
9.6
Pump flow control utilizing throttling.
9.7
Pump flow control utilizing pump speed.
9.8
Pump flow control energy savings.
9.9
Pump monitoring configuration.
9.10
Pump monitoring configuration.
9.11
Typical centrifugal pump.
9.12
Typical rotary screw positive displacement pump.
10.1
Typical condenser arrangement.
10.2
Typical condenser arrangement.
10.3
Two-stage air ejector system.
10.4
Steam turbine gland steam seal system.
11.1
Typical steam turbine equipment.
11.2
Impulse stage pressure and velocity response.
11.3
Velocity compounded impulse stage.
11.4
Pressure compounded stage.
11.5
Reaction stage pressure and speed response.
11.6
Rankine thermodynamic cycle.
11.7
Location of stop (or Throttle) valves and control (or governor) valves and concept of partial arc admission.
11.8
Simplified steam turbine valve arrangement.
11.9
High pressure (HP) steam turbine side view.
11.10
Turbine front standard.
11.11
Radial bearing numbering arrangement for turbine generator.
11.12
Radial shaft seals.
11.13
General machinery vibration severity chart.
12.1
Combustion turbine: compressor rotor assembly.
12.2
Combustion turbine: typical combustor assembly.
12.3
Combustion turbine: typical combustor arrangement.
12.4
Combustion turbine: turbine rotor assembly.
12.5
Combustion turbine: turbine casing assembly showing cooling air.
12.6
Combustion turbine: complete turbine assembly.
12.7
Typical flow diagram for combined cycle power plant.
13.1
Ideal ignition Otto thermodynamic cycle.
13.2
Two-stroke engine stages.
13.3
Four-stroke engine stages.
13.4
Ideal Diesel thermodynamic cycle.
13.5
Comparison of Otto and Diesel thermodynamic cycle with same compression ratio.
13.6
Comparison of Otto and Diesel thermodynamic cycle with different compression ratios.
14.1
Simple radial system.
14.2
Expanded radial system.
14.3
Primary selective system.
14.4
Primary loop system.
14.5
Typical secondary selective system.
14.6
Alternate secondary selective system.
14.7
Sparing transformer.
14.8a
Non-segregated phase bus duct.
14.8b
Non-segregated phase bus duct.
14.9a
Segregated phase bus duct.
14.9b
Segregated phase bus duct.
14.10a
Isolated phase bus duct.
14.10b
Isolated phase bus duct.
14.11
Single-line equivalent circuit for an energized 480 V, three-phase, 7.5 HP motor operating near full speed.
14.12
Single-line equivalent circuit for starting 480 V, three-phase, 7.5 HP motor assuming a high power factor.
14.13
Single-line equivalent circuit for starting 480 V, three-phase, 7.5 HP motor assuming a low power factor.
14.14
Compression lug.
14.15
Mechanical lug.
14.16
Stress cone.
14.17
Conduit system arrangement for Example 14.4.
14.18
Conduit system arrangement for Example 14.5.
14.19
Forces on pulley with cable at 90 degrees with two supports.
14.20
Forces on pulley with cable at 90 degrees with one support.
14.21
Forces on pulley with cable at 180 degrees with one support.
14.22
Typical active cathodic protection circuit.
15.1
Ideal single-phase transformer model.
15.2
Response of three-phase transformer to line-to-ground fault.
15.3
Autotransformer single-line equivalent circuit.
15.4
Current limiting reactor.
15.5
Standard impulse test waves.
15.6
Transformer equivalent circuit.
15.7
Non-standard transformer phase shift application.
16.1
Typical synchronous machine arrangement.
16.2
Generator winding configurations.
16.3
Coil assembly in slot area.
16.4
Roebel transposition.
16.5
Coil assembly in slot area.
16.6
Typical lamination section with ventilation channels.
16.7
Generator stator with rotor removed.
16.8
Flux probe mounted in generator stator.
16.9
Flux probe waveform.
16.10
RTD mounted in generator stator between top and bottom coils.
16.11
Cylindrical rotor (GE) with diagonal flow air gap pickup (DFAGPU) hydrogen cooling system.
16.12
Simplified one-line diagram of power flow.
16.13
Typical capability curve for a hydrogen-intercooled machine.
16.14
Definition of leading and lagging operation for motors and generators and direction of reactive power flow.
16.15
Typical “V-curve” for a hydrogen-intercooled machine.
16.15a
“V-curve” solution for Example 16.6.
16.15b
“V-curve” solution for Example 16.7.
16.16
Three-phase short circuit decrement curve.
16.17
DC generator commutator exciter
16.18
Alternator rectifier: brushless exciter.
16.19
Potential source rectifier exciter.
16.20
Radial stud configuration.
16.21
Synchronizing relay (25).
16.22
Synchronizing meter.
16.23
Differential relay (87).
16.24
Exciter field ground monitor brush assembly.
17.1
Torque speed curves for various NEMA and IEC design motors.
17.2
Torque speed curves for NEMA design B motor.
17.3
Power triangle for motor absorbing reactive power from the system.
17.4
Power factor location for motor starter.
17.5
Power triangle for motor delivering reactive power to the system.
17.6
Induction motor kVA, kvar, kW and power factor in relation to load.
17.7
Synchronous motor kvar capability in relation to load.
17.8
Induction motor simplified equivalent model.
17.9
Induction motor
E
g
voltage or electromagnetic force versus speed curve.
17.10
Induction motor current versus speed curve.
17.11
Induction motor total power versus speed curve.
17.12
Induction motor real power versus speed curve.
17.13
Induction power factor versus speed curve.
17.14
Induction motor which is started across the line – torque versus speed (gray area) curve compared with variable torque load versus speed (black area) curve.
17.15
Induction motor which is started across the line – torque versus speed (gray area) curve compared with constant torque load versus speed (black area) curve.
17.16
Induction motor which is started with current limit reduced voltage starter – torque versus speed (gray area) curve compared with variable torque load versus speed (black area) curve.
17.17
Induction motor which is started with current limit reduced voltage starter – torque versus speed (gray area) curve compared with constant torque load versus speed (black area) curve.
17.18
Wound rotor motor three-line diagram.
17.19
Electronic soft-start three-line diagram.
17.20
One variable frequency drive controlling multiple motors.
17.21
Synchronous motor with eight poles and brushless exciter – main field.
17.22
Synchronous motor with eight poles and brushless exciter – main field and armature of brushless exciter.
17.23
Synchronous motor with eight poles and brushless exciter – stator core and windings.
17.24
Synchronous motor with eight poles and brushless exciter – armature of brushless exciter.
17.25
Synchronous motor with eight poles and brushless exciter – external of diode wheel.
17.26
Synchronous motor with eight poles and brushless exciter – internal of diode wheel.
17.27
Schematic of internal of diode wheel.
17.28
Motor torque and load torque application.
18.1
Motor torque-speed curve for different applied frequencies.
18.2
PWM VSD configuration.
18.3
PWM VSD voltage and current outputs.
18.4
LCI configuration.
18.5
LCI VSD SCR stack assembly.
18.6
Efficiency curves for flow control of fan or pump.
18.7
Torque-speed curve of standard motor showing high speed derate area (a) and low speed derate area (b).
18.8
Torque-speed curve of constant-power load.
18.9
Torque-speed curve of constant-torque load.
18.10
Torque-speed curve of variable (square)-torque load.
18.11
Torque-speed curve of variable (cube)-torque load.
18.12
Voltage vectors for 18-pulse rectifiers: second rectifier.
18.13
Voltage vectors for 18-pulse rectifiers: third rectifier.
18.14
Arrangement of 18-pulse drive isolation transformer for ±20 degree phase shift.
19.1
13.8 kV switchgear lineup.
19.2
Manual close and trip buttons and charge and position flags on circuit breaker.
19.3
Operating mechanism for medium voltage circuit breaker.
19.4
Vacuum bottle assembly of medium voltage circuit breaker.
19.5
13.8 kV switchgear breaker compartment.
19.6
Aftermath of an arc flash in a 13.8 kV breaker.
19.7
Circuit breaker close circuit schematic.
19.8
Circuit breaker trip circuit schematic.
19.9
Application of IEEE Standards to Switchgear.
20.1
Battery ground fault tracer operation.
20.2
Simplified DC distribution system.
21.1
Ground detection relay (59N) for a three-phase ungrounded system.
21.2
Balanced phase-to-ground voltages of an ungrounded system (no phase-to-ground fault).
21.3
Unbalanced phase-to-ground voltages of an ungrounded system (phase A-to-ground fault).
21.4
High impedance system protection relay showing zero sequence CT input.
21.5
Grounding arrangement for ground-fault protection in solidly grounded systems.
21.6
Grounding arrangement for ground-fault protection in resistance grounded systems.
21.7
Grounding arrangement for ground-fault protection in ungrounded systems.
22.1
Device 27, undervoltage relay.
22.2
Device 49, thermal relay.
22.3
Device 50, instantaneous overcurrent relay.
22.4
Device 51, time delay overcurrent relay.
22.5
Time-current curve (TCC) for time delay relay.
22.6
Typical relay time-current characteristics.
22.7
Device 51N, neutral-ground fault time delay overcurrent relay.
22.8
Device 59, overvoltage relay.
22.9
Device 81O and 81U, overfrequency and underfrequency relay.
22.10
Device 87, differential relay.
22.11
Simplified one line diagram of generator (
E
1
), generator reactance (
X
d
) and system (
E
2
).
22.12
Typical synchronous generator decrement curve.
22.13
Delta-to-wye conversion.
22.14
Wye-to-delta conversion.
22.15
Correct TCC Coordination.
22.16
Incorrect TCC Coordination.
23.1
Tangentially fired furnace.
23.2
Modulating feedback control loop.
23.3
Modulating feedback control loop with feedforward anticipatory signal in the lube oil loop.
23.4
Modulating feedback control loop with feedforward anticipatory signal in cooling water loop.
23.5
Modulating feedback control loop with feedforward anticipatory signal and a cascade loop.
23.6
Typical DCS Distribution System.
23.7
Typical DCS Graphic Display, Electrical.
23.8
Typical DCS Graphic Display Mechanical.
24.1
Comparison of accuracy to precision.
24.2
Series connection for thermocouple system.
24.3
RTD connection.
24.4
Typical orifice coefficients for water media.
24.5
Simplified manometer.
24.6
Potential transformer.
24.7
Current transformer.
24.8
Current transformer and potential transformer one line diagram.
24.9
Transformer polarity.
24.10
Sample metering scheme.
24.11
Typical electro-mechanical kWh demand meter nameplate.
24.12
General instrument or function symbols.
24.13
Measurement symbols: primary elements.
24.14
Measurement symbols: secondary instruments.
24.15
Line symbols.
24.16
Self-Actuated final control element symbols.
24.17
Final control element actuator symbols.
24.18
Control valve failure and de-energized position indications.
24.19
Final control element symbols.
24.20
Typical PID diagram showing piping and instrumentation.
24.21
Typical KLD diagram showing instrument loop.
25.1
Air actuated diaphragm control valve.
25.2
Symbol for a pneumatic actuated valve.
25.3
Symbol for a hydraulic actuated valve.
25.4
Symbol for a motor-actuated valve.
25.5
Ball valve cross section and schematic symbol.
25.6
Butterfly valve cross section and schematic symbol.
25.7
Check valve types and schematic symbol.
25.8
Gate valve cross section and schematic symbol.
25.9
Globe valve cross section and schematic symbol.
25.10
Relief valve cross section and schematic symbol.
25.11
Pneumatic pilot valve module assembly.
25.12
Pneumatic valve manifold port symbol.
25.13
Pneumatic valve manifold position symbol.
25.14
Typical pneumatic valve manifold position symbols.
25.15
Typical pneumatic valve manifold position symbols.
25.16
Example for manually operated, spring return, pneumatic valve manifold position symbol.
25.17
Example for pneumatic valve control system: air to close.
25.18
Example for pneumatic valve control system: spring return to open.
26.1
Dry electrostatic precipitator.
26.2
Selective catalytic reduction (SCR) system.
26.3
Forced oxidized wet limestone process.
26.4
Post-combustion carbon dioxide capture process.
27.1
Typical evaporation distillation process.
27.2
pH effect on boiler metal corrosion process.
27.3
Pump efficiency.
28.1
Parabolic trough solar collector assembly.
28.2
Parabolic trough solar power plant.
28.3
Solar power tower power plant.
28.4
Solar power tower plant.
28.5
Solar dish power plant.
28.6
The photovoltaic effect.
28.7
Typical equipment block diagram for PV array for utility distribution application.
28.8
Evaluation of phase-to-phase fault on collector bus.
28.9
Inverter power output as a function of the ambient temperature.
28.10
Inverter transformer load profile.
LIST OF ANNEX
A
NEMA Enclosure Types
B
IEEE Device Numbers and Functions
C
Common System Codes for Power Generation Facilities
D
Common Equipment Codes for Power Generation Facilities
E
Unit Conversion Factors
F
Solutions to Problems
ACKNOWLEDGMENTS
THE AUTHOR wishes to thank the many people who contributed their time, expertise, and encouragement to the development of the course material for the Energy Production Systems Engineering course at the University of South Florida (USF) Master's Degree Power Engineering Program and, subsequently, this textbook. I especially would like to thank Professor Joe Skala and Dr. Ralph Fehr.
Back in 1980, Professor Joe Skala, while still working as a full-time Professional Engineer at Florida Power Corporation, planted the seed that has since grown into the Power Engineering Program at USF. When Professor Skala started at USF as an Adjunct Professor, there were only two power courses offered at the university as electives. By the time Professor Skala retired in 2000, he had started the Power Engineering Program at USF and developed it into an independent master's degree offering. Under Professor Skala's guidance, the power program grew by about eight courses. Even after retirement in 2000, Professor Skala continued to support education by becoming an Adjunct Professor in the Mathematics Department at St. Petersburg Junior College (SPJC). During his time at SPJC, he, along with Professor Warren DiNapoli, donated his entire salary from teaching mathematics at the Clearwater campus of SPJC to the “DiNapoli and Skala Families Scholarship.” This scholarship is awarded to Clearwater campus students who have a demonstrated financial need, a GPA of 3.0 or higher and have completed a minimum of 24 semester hours. He was also an avid supporter to the “Women on the Way” (WOW) program at SPJC, which is a resource and support center developed to help women succeed in college.
Professor Skala touched many people over his lifetime including mine. While he is gone from us now, his influence is within all of his students and will remain with us for a long time to come.
Dr. Ralph Fehr's request to develop a course covering equipment and systems utilized in the electrical power generation industry is the reason there is an Energy Production Systems Engineering course at USF and this textbook. Dr. Fehr was instrumental in the further development of the USF Power Engineering Program after Professor Skala retired. Dr. Fehr joined the power program at USF in 1997. During his tenure at USF, Dr. Fehr has added eight more courses to the power program and, in 2005, Dr. Fehr successfully developed the power program into a PhD offering at USF. As part of this expansion of the power program, Dr. Fehr recommended adding the Energy Production Systems Engineering course to the power engineering curriculum to cover topics associated with the generation side of the utility industry. The intention was that this would be one piece to round out the program to cover all aspects of power engineering: generation, transmission, distribution, and utilization. Dr. Fehr invited me to develop the Energy Production Systems Engineering course material at USF and I was glad to take on the task. Dr. Fehr has been a major contributor of materials for both the university course and the textbook and has spent many hours providing valuable feedback to me. The success of the Energy Production Systems Engineering course at USF is in large part due to the efforts of Dr. Fehr.
Additionally, I would like to thank Joe Simpson with Duke Energy for providing valuable information for Chapter 6. I also would like to thank Bob Buerkel with Parker Pneumatic Division, North America, for his review and suggestions for the valve actuator section. Additionally, Ralph Painter with Tampa Electric has been a great mentor and provided me with technical information in the design, installation, operation, and maintenance of an energy production facility that I have incorporated into the course material. I appreciate the many hours of assistance that Paul Yauilla with Tampa Electric put into editing the images and figures in this textbook. Thank you also to Jane Hutt with National Electric Coil for her efforts on the graphics for the generator section. Divya Narayanan along with all the staff at Wiley-IEEE Publishers spent many hours working with me to develop the final version of this textbook and I greatly appreciate all of their efforts.
I also wish to thank Bill Fowler, Tracy McLellan, John Sheppard, Jack White, Fred Wyly, David Kiepke, Tim Pedro, Tim Parsons, Charles (Terry) Kimbrell, James Cooksey, Michael Burch, Jim Mitchell, Jim Johnson, Dave Ford, Peter Teer, Tim Hart, and all the other many engineers, operators, technicians, electricians, and mechanics that I have worked with over the years and who have freely shared their valuable wisdom and experience. Their many hours of guidance and support have provided me with the background which has allowed me to develop this college course and textbook.
Thomas H. Blair
INTRODUCTION
THOMAS EDISON opened the first commercial electric power generation station in the United States on September 4, 1882, in New York City. This station generated “direct current” electrical energy for distribution locally in Manhattan. Soon after, on November 16, 1896, Nicholas Tesla and George Westinghouse opened a generation station in Niagara, NY, that generated “alternating current” energy. Initially, generation was located near the load center and the various load centers operated independently. Over time, it was determined that, to improve the reliability of the electric supply system and reduce costs, the many load centers and generation stations should be interconnected to a common “transmission” system thus leading to the interconnected systems of generation, transmission, distribution, and utilization that we have today.
Over the past century, power generation has undergone dramatic changes and innovation continues to drive changes and improvements in the electric generation industry. Today, sources of energy to generate electrical energy include coal, oil, natural gas, geothermal, wind, solar, biomass, hydro, tidal, and nuclear power.
Society has become very dependent on the availability of energy and electrical energy has become the primary means of distributing this energy.
The function of the generation station electrical engineer is to ensure a safe and reliable generation facility. The order of these two functions is not arbitrary. Safety is of primary concern for the generation utility engineer. Therefore, safety is the first chapter in this book. If a facility is not a safe facility for employees or the public, then it will not be a reliable facility. Unsafe conditions may not only result in personal injury but often involve equipment failure. An unsafe facility will likely have less reliable equipment and be a less reliable plant. While the primary goal of safety is to ensure the personal health and wellbeing of both the employees and the public, it also must be the primary focus for the utility engineer to ensure both safety and reliability.
This textbook is designed to provide a general introduction to the various facilities, systems, and equipment used in the power generation industry. It provides both theoretical and practical information for various utility systems. This text should provide a solid foundation on which a power generation facility engineer can continue to build.
It is my sincerest hope that this text will be useful in assisting utility electrical engineers to ensure safe and reliable operation of their facilities.
Thomas H. Blair
CHAPTER 1ELECTRICAL SAFETY
GOALS
To understand the basic requirements of OSHA 1910.269 and Subpart S
To apply recommendations of NFPA 70 (National Electrical Code
®
) and NFPA 70E (Electrical Safety in the Workplace) for compliance with OSHA 1910 Subpart S
To apply recommendations of IEEE C2 (National Electrical Safety Code) for compliance with OSHA 1910.269
To be able to determine minimum approach distance (MAD), limited approach boundary, restricted approach boundary, and arc flash boundary for installation
To be able to determine minimum safety clearance for electric supply station fences
To be able to determine the minimum illumination requirements for electric supply station locations
To be able to determine the proper electrical PPE (personal protective equipment) required for various tasks
To be able to determine the correct classification for areas where hazardous materials may be present
IF ONE were to try to reduce the function of the electrical engineer in the electric power generation industry to one sentence, it would be “to ensure the design, implementation, and operation of a SAFE and RELIABLE electrical system.” Electrical safety is of primary importance in the electric utility generation industry. The generation industry is unique from other industrial environments. The available short-circuit fault currents can be very large since the generation source is close and can supply a large amount of fault current. The service voltages at various pieces of equipment can be greater in magnitude for the larger electrical machines utilized in the generation station. Combustible materials may be handled, stored, and utilized in power generation facilities. The above conditions require the power plant electrical engineer to be very familiar with governmental regulations and industry standards regarding safety requirements to ensure the safe operation of the generation facility.
OSHA (Occupational Health and Safety Administration) (osha.gov) issues regulations that cover occupational health and safety. These regulations have the same effect as law. For general industry, which includes utilities, the applicable regulation is OSHA CFR 1910 – General Industry Standards. For general industry, electrical safety is covered under Subpart S. However, under OSHA CFR 1910, there is a separate section for special industries under Subpart R and the electric utility industry is covered under OSHA 1910.269 of Subpart R. This section covers the operation and maintenance of electric power generation systems and equipment and applies to installations utilized for the generation of electrical energy that are accessible only to qualified employees. One might think that all of the requirements for a generation facility fall under OSHA CFR 1910.269 and not OSHA CFR 1910 Subpart S since OSHA CFR 1910.269 regulations were written for electric generation, transmission, and distribution systems, but that is not always the case. So how does a plant engineer know when to apply OSHA 1910 Subpart S (general industry) or OSHA 1910 Subpart R 269 or possibly both regulations? OSHA provides guidance with that question in Appendix A of 1910.269.
To understand how Appendix A addresses this, we need to understand that OSHA segregates its safety requirements into two general categories: electrical safe installation methods and electrical safe work practices.
1910.269 Appendix A-1 as shown in Figure 1.1 answers the question of which regulation (1910.269 or 1910 Subpart S) applies to electrical installation requirements and 1910.269 Appendix A-2 as shown in Figure 1.2 answers the question of which regulation (1910.269 or 1910 Subpart S) applies to electrical safe work practices.
Figure 1.1 Appendix A-1 – Application of 1910.269 and 1910 Subpart S to Electrical Installations. .
Source: Reproduced with permission of U.S. Department of Labor
Figure 1.2 Appendix A-2 – Application of 1910.269 and 1910 Subpart S to Electrical Safety-Related Work Practices. .
Source: Reproduced with permission of U.S. Department of Labor
For regulations regarding the safety of the electrical installation, if the facility is directly associated with a generation, transmission, or distribution system, then OSHA CFR 1910.269 is the regulation that describes safe installation requirements. If the facility is not directly associated with generation, transmission, and distribution, then 1910 Subpart S applies. For example, if we were to install a motor control center (MCC) in the turbine building of an electric utility generation station, then the safe installation regulations would be defined by 1910.269. However, if we were to install an MCC in a warehouse that is not located on the generation station facility, then the safe installation regulations would be defined by 1910 Subpart S.
The choice of which OSHA standard to use for electrical safe work practices depends both on the location of the work and the qualification of the personnel performing the electrical work. First, we must answer the question, what defines a “qualified person.” OSHA defines a qualified person as one who has “received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved” (OSHA 1910.399).
For electrical safe work practice regulations, if the personnel performing the task are not qualified, then the safe work practices of Subpart S are the regulations that govern the work regardless of whether the installation where the work is being performed is on a generation facility or not. For example, if we were to install an air compressor in a generation facility and the equipment supplier is sending a field engineer to assist with startup of the compressor and the field engineer is not trained on the electrical safe work practices of OSHA 1910.269, then the safe work practices for this task must comply with OSHA Subpart S, even though this task is being performed at a generation facility.
However, if the personnel performing the task are qualified AND if the installation is a generation facility, then the safe work practices of 1910.269 apply to the task. So for normal maintenance done at the generation station where the task is performed by station personnel that are trained according to OSHA 1910.269, the tasks are covered under OSHA 1910.269. For commingled installations, the reader is directed to OSHA 1910.269, Appendix A for guidance.
As the reader can see, even though OSHA 1910.269 is written for generation, transmission, and distribution systems, there are instances where OSHA 1910 subpart S applies, so the electric utility engineer must know and understand the installation requirements and safe work practices of both OSHA 1910 Subpart S (general industry) and OSHA 1910.269 (electric utilities).
So where does the electric utility engineer obtain guidance on how to comply with all of these regulations? For the safe installation requirements for general industry described by OSHA 1910 Subpart S (sections 302 to 308), NFPA 70® (National Electric Code® or NEC®) provides guidance on how to comply with these federal regulations. (NFPA 70®, National Electrical Code®, and NEC® are registered trademarks of the National Fire Protection Association, Quincy, MA). For the safe installation requirements for the electric utility industry of OSHA 1910.269, IEEE C2 (National Electrical Safety Code or NESC) provides guidance on how to comply with federal regulations at generation station installations. Specifically, IEEE C2 – Part 1 describes electric supply station installation requirements, IEEE C2 – Part 2 describes overhead line installation requirements, IEEE C2 – Part 3 describes underground line installation requirements.
For the safe work practice requirements for general industry of OSHA 1910 Subpart S (sections 332 to 335), NFPA 70E (Electrical Safety in the Workplace) provides guidance on how to comply with federal regulations. For the safe work practice requirements for the electric utility industry of OSHA 1910.269, IEEE C2 – Part 4 – (NESC) provides guidance on how to comply with federal regulations.
While these codes are not law or regulation, they are referenced by OSHA federal regulation as methods to ensure compliance with the law. Additionally, OSHA regulation updates take many years to occur due to the process of public notification and comment before changing official regulations. However, NEC® is updated every 3 years, NFPA 70E is updated every 4 years, and NESC is updated every 5 years. Therefore, these codes have the most up-to-date information regarding electrical safety. The electric generation utility engineer should have a current copy available of all three of these standards and be familiar with the information contained within. In Chapter 1, we describe just some of the installation and safe work practice information contained in these codes. The reader is reminded to always check the latest version of the codes for updates.
One last note of caution, the OSHA standards and associated codes are NOT design guides, but MINIMUM requirements. When applying these codes, remember that these are the MINIMUM standards to ensure safety; but good engineering practice may suggest additional safety measures in some instances.
INSTALLATION SAFETY REQUIREMENTS—GENERAL INDUSTRY (NEC®)
Access to Working Space <600 V
To ensure the safety of personnel when accessing exposed electrical parts of equipment, minimum equipment clearances are given in codes and standards depending on the nominal voltage of the circuit in question and the equipment. If the structures surrounding the area are neither energized nor grounded (if structures are insulated), then the second column in Table 1.1 applies. If the structure surrounding the area is grounded, then the third column in Table 1.1 applies (note that conductive or partially conductive materials such as concrete are considered grounded). If the structure surrounding the area is energized, then the fourth column in Table 1.1 applies. Additionally, the working space must be of sufficient width, depth, and height to permit all equipment doors to open 90 degrees. The width of the working space must be at least the width of the equipment and cannot be less than 30 in.
TABLE 1.1Minimum Aisle Working Space for Nominal Voltage Less than 600 V
Nominal Voltage to Ground (V)
Live to Not Ground or Not Live
Live to Ground
Live to Live
0–150
900 mm
900 mm
900 mm
3 ft
3 ft
3 ft
151–600
900 mm
1.1 m
1.2 m
3 ft
3.5 ft
4 ft
Source: Reproduced with permission from NFPA 70®, National Electrical Code®, Copyright © 2014, National Fire Protection Association. This is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety. The student may download a free copy of the NFPA 70® standard at: http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=70.
Remember that these are minimum requirements. There may be instances where the working space needs to be even larger than the values required by codes. One example where this commonly occurs is in front of switchgear where the breakers can be racked out and removed (this is described in more detail in Chapter 19: Switchgear). The space required for the racking device (including clearance to other energized equipment in the area) commonly is larger than the minimum requirements of code. The design engineer should evaluate both the equipment to be installed and the typical types of maintenance that will be performed and ensure that the working space provided is adequate for personnel safety.
In regard to access to rooms containing electrical equipment, if the service provided is less than 1200 A, then there must be at least one entrance consisting of a minimum of 24-in.-wide by 6-ft-high door provided with panic hardware that allows for egress from the working space by pushing on door from the inside of the building. Where the electrical equipment is wider than 6 ft, there must be two doors.
If the service provided is greater than 1200 A, then a minimum of two, 24-in.-wide by 6-ft-high doors must be provided with panic hardware that allows for egress from either side of working space by pushing on door. This again is an area where these are minimum requirements. If, during the process of performing maintenance such as racking out equipment, one means of egress may become blocked, the design engineer would be justified in adding additional means of egress for personnel.
Access to Working Space >600 V
In rooms and enclosures where the voltage exceeds 600 V, NEC® requires rooms to be locked and signage to be posted that reads,
For equipment that nominally operates in excess of 600 V, Table 1.2 describes the minimum working space requirements. The same conditions for surrounding equipment that applied to Table 1.1 apply to Table 1.2. If the structures surrounding the area is neither energized nor grounded (if structures are insulated) then the second column in Table 1.2 applies. If the structure surrounding the area is grounded, then the third column in Table 1.2 applies. If the structure surrounding the area is energized, then the fourth column in Table 1.2 applies.
TABLE 1.2Minimum Aisle Working Space for Nominal Voltage >600 V Around Electrical Equipment
Voltage ph-gnd
Live vs. Insulated
Live vs. Gnd
Live vs. Live
601 V to 2,500 V
900 mm (3 ft)
1.2 m (4 ft)
1.5 m (5 ft)
2,501 V to 9,000 V
1.2 m (4 ft)
1.5 m (5 ft)
1.8 m (6 ft)
9,001 V to 25 kV
1.5 m (5 ft)
1.8 m (6 ft)
2.8 m (9 ft)
25,001 V to 75 kV
1.8 m (6 ft)
2.5 m (8 ft)
3.0 m (10 ft)
Above 75 kV
2.5 m (8 ft)
3 m (10 ft)
3.7 m (12 ft)
Source: Reproduced with permission from NFPA 70®, National Electrical Code®, Copyright © 2014, National Fire Protection Association. This is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety. The student may download a free copy of the NFPA 70® standard at: http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=70.
Example 1.1 You are designing an MCC that is powered from a 480 Vac phase-to-phase, 277 Vac phase-to-ground source. You will place the MCC in an electrical equipment room where the wall across the aisle from the 480 V circuits is grounded. What is the minimum aisle working space for this application?
Solution: Referring to Table 1.1, we find the minimum aisle working space to be 3.5 ft.
For exposed energized conductors located outdoors, NEC® requires that the conductors be enclosed in a fence that is 7 ft minimum in height. Table 1.3 describes the minimum distance from the fence to the live part being protected.
TABLE 1.3Minimum Distance from Fence to Live Parts
Minimum Distance from Fence to Live Parts
Nominal Voltage
m
ft
601–13,799 V
3.05
10
13,800–230,000 V
4.57
15
Over 230,000 V
5.49
18
Source: Reproduced with permission from NFPA 70®, National Electrical Code®, Copyright © 2014, National Fire Protection Association. This is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety. The student may download a free copy of the NFPA 70® standard at: http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=70.
NEC® defines the minimum allowable branch circuit conductor size for a given branch circuit breaker. Following matrix is a summary of branch circuit minimum conductor sizes based on branch circuit protection.
Breaker
15 A
20 A
30 A
40 A
50 A
Conductor
14 AWG
12 AWG
10 AWG
8 AWG
6 AWG
Just to reinforce the notion that codes are not design standards, the size of the conductor recommended by NEC® is not the required conductor size, but the minimum allowable conductor size. For long runs where voltage drop might be an issue, the design engineer might choose to oversize the branch circuit conductor which is acceptable. Codes such as NEC® and NESC are not design guides, but only provide the minimum safety requirements for installation.
Grounding and bonding is so important that it has its own chapter and is described in Chapter 21. But for safety, it is worth mentioning here that NEC® requires the electrical distribution system to be grounded and bonded and requires the electrical distribution system to have one main bonding jumper between the main supply neutral bar and ground bar. The functions of the grounding conductor (also known as neutral conductor) and bonding conductor (sometimes referred to as the grounded conductor) are distinctly different. Downstream equipment enclosures are bonded back to the main supply ground bar via the grounded conductor and downstream equipment neutral terminations are connected back to the main supply neutral bar via the grounding conductor. The purpose of the grounding conductor is to provide a path for current to return to the source and, if there is a phase-to-neutral fault, this current will clear the upstream breaker to remove the fault from the energized electrical system. The purpose of the grounded conductor is not to provide a path for fault current, but to maintain electrical continuity between system ground and equipment enclosures in the field. This is done to minimize touch potentials during faults to protect personnel.
INSTALLATION SAFETY REQUIREMENTS—SPECIAL INDUSTRY – UTILITY (NESC)
Access to Exposed Energized Conductors Outdoor
In some areas of a generation facility, there may be exposed overhead conductors. A typical application is where the plant interfaces with the transmission and distribution system. There are minimum distances that need to be maintained from the general public to these exposed circuit conductors. In order to keep non-qualified personnel from accessing the energized circuits, NESC provides guidance on minimum fence space requirements between energized conductors and the fence. This is very similar to the requirements of NEC® mentioned in Table 1.3.
Table 1.4, along with Figure 1.3, shows the minimum radius from a point on the fence 5 ft from grade to the exposed energized conductor to ensure non-qualified people are not exposed to the hazard presented by exposed energized conductors. Note, the fence height must be 7 ft minimum and the fence must be grounded to the ground grid to limit touch potential (touch potential is explained in Chapter 21: Ground System).
Figure 1.3 Safety clearance to electric supply station fences. .
Source: Reproduced with permission of IEEE
Table 1.4 Values of Minimum Distance from Fence to Outdoor Exposed Energized Conductor for Use with NESC Figure 110-1
Dimension “R”
Nominal Voltage Between Phases (V)
Typical BIL
m
ft
151–7,200
95
3
10
13,800
110
3.1
10.1
23,000
150
3.1
10.3
34,500
200
3.2
10.6
46,000
250
3.3
10.9
69,000
350
3.5
11.6
115,000
550
4
13
138,000
650
4.2
13.7
161,000
750
4.4
14.3
230,000
825
4.5
14.9
230,000
900
4.7
15.4
Source: Reproduced with permission of IEEE.
NESC also provides guidance for exposed overhead lines and minimum clearance from ground depending on the type of traffic that is expected below the exposed lines. This information is found in NESC Part 2, section 232, and summarized in Table 232-1. For example, for exposed conductors energized at less than 750 Vac, the following minimum clearances apply. For areas where only pedestrian traffic is expected, 3.6 m (12 ft) is the minimum clearance from ground to the overhead lines. For areas that transverse residential driveways, parking lots, and alleys, 4.9 m (16 ft) is the minimum clearance from ground to overhead lines. For areas where exposed conductors transverse roads, streets, and areas exposed to truck traffic, 4.9 m (16 ft) is the minimum clearance from ground to overhead lines. For areas where exposed conductors transverse track rails of rail roads, 7.3 m (24 ft) is the minimum clearance from ground to overhead lines. All of these distances are to be maintained during periods of maximum line sag. This data is summarized in Table 1.5.
TABLE 1.5Minimum Overhead Clearance from Ground to Outdoor Exposed Energized Conductor (for V < 750 Vac)
3.6 m (12 ft) – sidewalks and areas accessible to pedestrians only
4.9 m (16 ft) – residential driveways, parking lots, and alleys
4.9 m (16 ft) – roads, streets, and areas exposed to truck traffic
7.3 m (24 ft) – track rails of rail roads
Source: Reproduced with permission of IEEE.
Example 1.2 You are designing an exposed overhead distribution line that is crossing a sidewalk that will be accessible to pedestrian traffic only. What is the minimum from ground to the overhead line for this application?
Solution: Minimum clearance from ground to overhead line for this application per Table 1.5 is 12 ft.
NESC requires a minimum level of illumination depending on the location or the work place in the generation facility and NESC Table 111-1 provides this guidance. This is to ensure that the area is adequately illuminated for the typical tasks performed in these areas to be performed safely. Table 1.6 is a partial listing of locations in a typical generation facility and the minimum required illumination levels.
TABLE 1.6Illumination Levels Required in an Electric Utility Power Generation Station
Location
Lux
Foot-Candles
Generating Station (Interior)
Highly critical areas occupied most of the time
270
25
Areas occupied most of the time
160
15
Critical areas occupied infrequently
110
10
Areas occupied infrequently
55
5
Generating Station (Exterior)
Building pedestrian main entrance
110
10
Critical areas occupied infrequently
55
5
Areas occupied occasionally by pedestrians
22
2
Areas occupied occasionally by vehicles
11
1
Areas occupied infrequently
5.5
0.5
Remote areas
2.2
0.2
Substation
Control building interior
55
5
General exterior horizontal end equipment vertical
22
2
Remote areas
2.2
0.2
Source: Reproduced with permission of IEEE.
In addition to normal lighting requirements listed in Table 1.6, NESC requires emergency lighting to be provided that is energized from an independent source (typically a battery) at locations of egress to provide for safe exit during emergencies such as fire where normal lighting is de-energized. The minimum illumination level at these exits is 11 lux (1 foot-candle) and the independent source must keep the emergency light energized for at least 90 minutes.
Just like NEC®, the NESC requires a minimum amount of working space around electrical equipment. A minimum of 7 ft of head room is required with a minimum working depth in front of equipment of 3 ft. For voltages <600 Vac, the values in NESC are the same as the values in NEC® as shown in Table 125-1 of NESC as described in Table 1.7. For voltages >600 V, the values in NESC listed in Table 124.1 of NESC as described in Table 1.8.
TABLE 1.7Working Space <600 V
Clear Distance
Condition 1
Condition 2
Condition 3
Voltage to Ground (V)
mm
ft
mm
ft
mm
ft
0–150
900
3
900
3
900
3
151–600
900
3
1070
3 − 1/2
1200
4
Source: Reproduced with permission of IEEE.
Condition 1: Exposed energized parts on one side and no energized or grounded parts on the other side of the working space.
Condition 2: Exposed energized parts on one side and grounded parts on the other side of the working space.
Condition 3: Exposed energized parts on both sides of the working space.
TABLE 1.8Working Space >600 V
NESC Table 124-1 – Working space >600 V
Column 1
Column C
Column 2
Column 3
Column 4
Max Design Voltage Between Phases
Basic Impulse Insulation Level (BIL)
Vertical Clearance of Unguarded Parts
Horizontal Clearance of Unguarded Parts
Clearance Guard to Live Parts
kV
kV
ft
in
ft
in
ft
in
0.3
–
Not specified
Not specified
Not specified
0.6
–
8
8
3
4
0
2
2.4
–
8
9
3
4
0
3
7.2
95
8
10
3
4
0
4
15
95
8
10
3
4
0
4
15
110
9
0
3
6
0
6
25
125
9
1
3
7
0
7
25
150
9
3
3
9
0
9
35
200
9
6
4
0
1
0
48
250
9
10
4
4
1
4
72.5
250
9
10
4
4
1
4
72.5
350
10
5
4
11
1
11
121
350
10
5
4
11
1
11
121
550
11
7
6
1
3
1
145
350
10
5
4
11
1
11
145
550
11
7
6
1
3
1
145
650
12
2
6
8
3
8
169
550
11
7
6
1
3
1
169
650
12
2
6
8
3
8
169
750
12
10
7
4
4
4
242
550
11
7
6
1
3
1
242
650
12
2
6
8
3
8
242
750
12
10
7
4
4
4
242
900
13
9
8
3
5
3
242
1050
14
10
9
4
6
4
Source: Reproduced with permission of IEEE.
NESC has requirements for the safety of rotating equipment, safety of battery systems, safety of transformers, conductors, circuit breakers, fuses, and switchgear. These safety requirements are discussed in the respective sections of this book to reinforce the importance of safety in the design and operation of this equipment.
Now that we have discussed installation safety requirements, we will discuss electrical safe work practice requirements.
SAFE WORK PRACTICE REQUIREMENTS
So what are the potential hazards in a power plant environment in regard to safe work practices? Some of the possibilities are electrical shock, arc flash, arc blast, fall, projectiles, and fire ignition.
Electrical shock occurs when a part of the body comes in contact with an energized circuit. To avoid this hazard, the employee must know the various electrical energy sources, be able to identify the voltage level associated with the hazard, determine what actions are necessary to reduce and/or eliminate the hazard, and be allowed to take those actions to avoid the hazard. The preferred method for prevention of electrical shocks is to ensure that the circuit is de-energized by placing it in an electrically safe work condition prior to performing work on that circuit. If it is determined that the circuit cannot be de-energized, then NFPA 70E and NESC Part 4 provide guidance of procedures and equipment to be utilized when working on a system energized. This is known as energized electrical work.
