Many smaller substations have no control house and do not need one since the power transformer is protected by power fuses; eliminating the need for relays, a battery bank and charger, and communications equipment. Typically these small substations have been located in remote rural areas which have very light loads; however, rural isn’t quite as rural as it once was, and these substations are now being loaded at much higher levels. With these increased loads due to the increased number of customers served by the substations, the utility may find it desirable and/or necessary to upgrade the power transformer’s protection from a set of power fuses to a circuit switcher. The utility would understandably like to accomplish this upgrade at the lowest possible cost without sacrificing reliability, and if it was not necessary to add a control house to the substation a significant cost savings would be realized. This paper provides full information on a circuit switcher solution which can provide current sensing, fault interruption, an uninterruptible power supply, a capacitor trip device, a digital protection relay, and an RTU–all integrated into a single product package to produce full functionality at a fraction of the cost of adding a substation control house. This solution, its full capabilities, and its advantages to the utility (financial, functional, and otherwise) will be covered in this paper.
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Archive for July, 2009
Transformer Protection
Friday, July 31st, 2009Reactive Power Supply and Consumption
Thursday, July 30th, 2009Table of Contents
Preface ………………………………………………………………………………………………………….. 2Executive Summary ………………………………………………………………………………………… 3
Chapter 1 Introduction:What Is Reactive Power and Why Are We Concerned About It?………………………….. 17
Chapter 2 Physical Characteristics and Costs of Reactive Power in AC Systems…. 25
Chapter 3 History of Reactive Power Pricing……………………………………………………45
Chapter 4 International Reactive Power Markets…………………………………………. 59
Chapter 5 Existing Reactive Power Issues………………………………………………………. 65
Chapter 6 Pricing and Procurement Options for Reactive Power……………………….. 85
Chapter 7 Conclusions, Recommendations and Questions………………………………..105
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Reactive power
Thursday, July 30th, 2009The notion of reactive power has been introduced long time ago because of its advantages to describethe behaviour of a power system. Among these advantages are the facts that the reactive power is ascalar quantity (therefore easy to manipulate) and that it is conserved over any network.Over the time, the meaning of the original concept of reactive power has been lost and today the“reactive power” is used for the maximum reactive power that flows through a piece of electricnetwork. The change of meaning is the origin of a few misconceptions that are present in almost everytextbook today. This article reanalyzes the reactive power concept, identifies the present contradictionsand defines clearly the differences between reactive and active power.
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Mechanics of Materials
Thursday, July 30th, 2009contents:
Concept of Stress
Review of Statics
Structure Free-Body Diagram
Component Free-Body Diagram
Method of Joints
Stress Analysis
Design
Axial Loading: Normal Stress
Centric & Eccentric Loading
Shearing Stress
Shearing Stress Examples
Bearing Stress in Connections
Stress Analysis & Design Example
Rod & Boom Normal Stresses
Pin Shearing Stresses Pin Bearing Stresses
Stress in Two Force Members
Stress on an Oblique Plane
Maximum Stresses
Stress Under State of Stress
Factor of Safety
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more books on mechanics of material
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Central Air Conditioning
Thursday, July 30th, 2009Regardless of the style of the system, the basic
components and method of operation are similar for all
electric compression-cycle systems. The major elements
are an evaporator coil, a condenser coil, fans to circulate
air over both coils, tubing to carry a refrigerant between
the two coils, a compressor to move the refrigerant
through the system, and a metering device to regulate the
rate of refrigerant low.
Air conditioning systems use several basic principles of
physics to remove heat from within a house: (1) a refrigerant
absorbs heat when it changes from a liquid to a gas; (2) a refrigerant releases heat when it changes from a gas to
a liquid; and (3) heat moves from a medium at a high
temperature to a medium at a lower temperature.
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Simulink / Matlab Tutorial – Low Pass Filter
Thursday, July 30th, 2009objective
.Ideal low pass filter
.Simple RCow pass filter
.Simulink Demonstration
.Matlab Demonstration
-transfer function
-bode(system magnitude & phase plots -f,w)
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Storm Sewer Maintenance
Thursday, July 30th, 2009This chapter of the Toolbox describes various maintenance practicesfor the separate storm sewer system and provides a few easy tips forconducting the work in a way that helps protect the environment:ïInspecting the systemïCleaning and repairing storm sewer pipes and stormdrain inletsïCleaning ditches and stream channelsïMaintaining detention ponds and other stormwatertreatment devicesA handy storm sewer system checklist is provided on thenext page.
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Electric Machinery Fundamentals
Wednesday, July 29th, 2009CHAPTER 1: INTRODUCTION TO MACHINERY PRINCIPLES 1
CHAPTER 2: TRANSFORMERS
CHAPTER 3: INTRODUCTION TO POWER ELECTRONICS 63
CHAPTER 4: AC MACHINERY FUNDAMENTALS 103
CHAPTER 5: SYNCHRONOUS GENERATORS 109
CHAPTER 6: SYNCHRONOUS MOTORS 149
CHAPTER 7: INDUCTION MOTORS 171
CHAPTER 8: DC MACHINERY FUNDAMENTALS 204
CHAPTER 9: DC MOTORS AND GENERATORS 214
CHAPTER 10: SINGLE-PHASE AND SPECIAL-PURPOSE MOTORS 270
APPENDIX A: REVIEW OF THREE-PHASE CIRCUITS 280
APPENDIX B: COIL PITCH AND DISTRIBUTED WINDINGS 288
APPENDIX C: SALIENT POLE THEORY OF SYNCHRONOUS MACHINES 295
APPENDIX D: ERRATA FOR ELECTRIC MACHINERY FUNDAMENTALS 4/E 301
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Download Matlab ebooks
Wednesday, July 29th, 2009Here we present a big collection of Matalb ebooks
Using Matlab in Linear Algebra
Download Free Engineering Books.
Tuesday, July 28th, 2009How to download free engineering books from our site just after reading any summary of a book you will see a red link just right click and choose save target as and you will get the book downloaded