TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB

Transmission and Distribution line's lightning performance can be improved by several special methods that have been used with some success. This article will give a brief review of the best known of these special methods. Designers should recognize, however, that industry experience has usually been limited to a few applications, and more experience is being accumulated. Additional shield wires Since the mid 1910s, it has been recognized that OHGWs on a transmission line reduce the lightning voltage created across the insulators. This reduction comes about in the three following ways: a) By intercepting strokes that would otherwise hit the phase conductors b) By draining off part of the stroke current that would otherwise ßow through the footing impedance c) By increasing the common-mode coupling of voltage surges on the shield wires to the phase conductors, causing the insulator voltage at the tower to be reduced Only the first of these effects requires the g...

ANSI C37.121-1989 standard covers the requirements for three-phase unit substations for step-down operation in the range of 112.5 kVA through 10 000 kVA at primary voltages of 601 volts through 38 kilovolts. The standard is intended for use as the basis for the coordination of equipment by assisting in the selection of components. A variety of designs for unit substations are possible using various combinations of incoming sections, transformer sections, outgoing sections, and transition (throat) sections. Since the transformer section determines the kVA and voltage capabilities of a unit substation, the ratings of the various types of unit substations are described in terms of transformer capability. Below are the unit substation requirement standard ratings as per ANSI C37.121-1989 The rating of each section of a unit substation shall comply with the applicable standards for its components and shall be equal to or greater than the rating ...

Schaum's Easy Outline Electromagnetics Boiled-down essentials of the top-selling Schaum's Outline series for the student with limited time What could be better than the bestselling Schaum's Outline series? For students looking for a quick nuts-and-bolts overview, it would have to be Schaum's Easy Outline series.  Every book in this series is a pared-down, simplified, and tightly focused version of its predecessor. With an emphasis on clarity and brevity, each new title features a streamlined and updated format and the absolute essence of the subject, presented in a concise and readily understandable form. Graphic elements such as sidebars, reader-alert icons, and boxed highlights stress selected points from the text, illuminate keys to learning, and give students quick pointers to the essentials. Designed to appeal to underprepared students and readers turned off by dense text Cartoons, sidebars, icons, and other graphic pointers get the material...

Machinery's Handbook Celebrating nearly 100 years as The Bible of the Mechanical Industries , the book brings together volumes of knowledge, information and data gathered, revised and improved upon from experts throughout the mechanical industries. Extraordinarily comprehensive yet easy to use since it premiered, Machinery s Handbook provides mechanical and manufacturing engineers, designers, draftsmen, toolmakers, and machinists with a broad range material, from the very basic to the more advanced.  It has always, and continues to provide industry fundamentals and standards while it moves into the 21st century with material reflecting technological advances and offering vast editorial improvements, making it the best tool...ever! A new more usable organization...every section has been reformatted so that you will never have to search outside of that area for information on the topic you are exploring. 30% MORE math coverage...from the basic to the advanced, you...

These aerial cables consist of separate conductors which use spacing between conductors to obtain a voltage rating. There are three major types of aerial conductors used for electrical transmission and distribution. AAC - All Aluminium Conductor  AAAC - All Aluminium Alloy Conductor  ACSR - Aluminium Conductor Steel Reinforced  The choice of conductor is determined by current rating and stringing conditions (span length, sag, everyday stress, ambient temperature and wind velocity, and worst case conditions of wind and ice). Conductor characteristics such as strength to weight ratio, ultimate tensile strength, modulus of elasticity, area, coefficient of linear expansion, AC resistance will determine the most suitable conductor. AAC - All Aluminium Conductor is made up of one or more strands of hard drawn 1350 Aluminium Alloy. Because of its relatively poor strength-to-weight ratio, AAC has had limited use in transmission lines and rural distribution because of th...

The relationship between the withstand voltage level using high direct voltage and the equivalent withstand voltage using power frequency voltage cannot be precisely stated because the relationship is composed of many factors. The lack of a precise equivalence should not cause concern because the purpose of proof tests is to demonstrate that the insulation can withstand the overvoltages to be expected in service rather than to establish the precise value of electrical strength. The electrical strength has been found in cases studied to be associated with impulse strength. Therefore, a direct voltage proof test may indicate ability of the insulation to withstand surges and short-time overvoltages approximating the same peak value. The test overvoltage value also provides for insulation deterioration in a further period of operation. The proper high direct voltage proof test for insulation need not necessarily be related to the corresponding power frequ...

High Voltage Testing courtesy of Siemens Lab IEEE Std 95-1977 is entitled IEEE Recommended Practice for Insulation Testing of Large AC Rotating Machinery with High Direct Voltage. It speaks of recommended practice during and for of testing insulation with direct voltages higher than 5 kV of large ac rotating machines rated at 10000 kVA or greater.  The purpose of this recommended practice is: 1)To provide uniform procedures for performing high direct voltage acceptance tests and routine maintenance tests on the main ground insulation of windings of large ac machines 2)To provide uniform procedures for analyzing the variations in measured current so that any possible relationship of the components of these variations to the condition of the insulation can be more effectively studied 3)To define terms which have a specific meaning as used in this document Below is the recommended safety precaution during high direct voltage testing of...

Handbook of Small Electric Motors A complete, definitive source for the design, manufacture, application, and testing of small electric motors less than ten horsepower *Gives motor design engineers, test technicians, and engineers top-to-bottom coverage of materials used in motor manufacturing, as well as how-to advice on selecting the right design and assembly method *Includes a full section on motor applications A COMPENIUM OF EXPERT INFORMATION ON TODAY'S DESIGNS, METHODS, AND MATERIALS-- Get up to speed on the latest design and manufacturing tools and techniques with this expert guide from leaders of the motor industry. A superb source of innovative, productivity, and profit-increasing solutions, HANDBOOK OF SMALL ELECTRIC MOTORS gives you more help with selection, calculation, assembly methods, and on-the-spot data than you can find anywhere else. There's no other source that approaches this unique reference for comprehensive, clear coverage of small motor ...

Electric Motors and Drives Electric Motors and Drives is intended for non-specialist users of electric motors and drives, filling the gap between maths- and theory-based academic textbooks and the more prosaic 'handbooks', which provide useful detail but little opportunity for the development of real insight and understanding. The book explores all of the widely-used modern types of motor and drive, including conventional and brushless D.C., induction motors and servo drives, providing readers with the knowledge to select the right technology for a given job. The third edition includes additional diagrams and worked examples throughout. New topics include digital interfacing and control of drives, direct torque control of induction motors and current-fed operation in DC drives. The material on brushless servomotors has also been expanded. Austin Hughes' approach, using a minimum of maths, has established Electric Motors and Drives as a leading guide for electric...

Photo Courtesy of http://www.ohmic.com.br Petersen Coil is agrounding reactor, used in alternating-current power transmission systems, which is designed to limit the current flowing to ground at the location of a fault almost to zero by setting up a reactive current to ground that balances the capacitive current to ground flowing from the lines. It was invented by one of our Electrical Engineering Heroes, Waldemar Petersen. This entry is a collection of articles about Petersen Coil. Its significance, application, and technical papers that involves the use of Petersen Coil. EARTH FAULT ARC SUPPRESSION COILS (Petersen Coils) The arc suppression coil consists of several following basic parts: cylindrical tank made of smooth sheet with magnetic circuit and main, auxiliary aswell as measuring winding (connected to bushings placed on the tank cover) fixedinside the tank, undercarriage (for one coil type several undercarriages can be chosen), expansion tank taking the expand...

Waldemar Petersen The name Waldemar Petersen may not really ring a bell. But, if mentioned alongside his, famous invention, the Petersen Coil, things will be different. Waldemar or Valdemar in some language is a professor of Electrical Engineering at TH Darmstadt. He was born on June 10 1880 in Athens. It was at Darmstadt where Petersen developed still further, then young AC technology. His involvement in the Alternating Current technology led to the invention of Petersen Coil. It is a grounding reactor, used in alternating-current power transmission systems, which is designed to limit the current flowing to ground at the location of a fault almost to zero by setting up a reactive current to ground that balances the capacitive current to ground flowing from the lines. Aside from this, he invented a watt metric ELR, developed the W metric ELR, and developed the theory of the electric field and electric punch where he wrote the first basic textbooks on these areas. N...

Proper system grounding will means safety. Its goals are to minimize voltage and thermal stresses on equipment, provide personnel safety, reduce communications system interference, and give assistance in rapid detection and elimination of ground faults. With the exception of voltage stress, operating a system as ungrounded, high-impedance grounded, or resonant grounded restricts ground fault current magnitudes and achieves most of the goals listed above. The drawback of these grounding methods is that they also create fault detection (protection) sensitivity problems. We can create a system grounding that reduces voltage stress at the cost of large fault current magnitudes. However, in such a system the faulted circuit must be de-energized immediately to avoid thermal stress, communications channel interference, and human safety hazards. The disadvantage of this system is that service must be interrupted even for temporary faults. Ungro...

This good resource includes individual authors who have familiar names and good reputations in the industry. This selection of topics is excellent with regard to devices and applications. Editor Skvarenina wisely has included the latest description of advanced motor and power control applications, offering this volume some staying power as a reference, as new technology and applications continue to emerge. Most of material is written at the upper academic level and would probably better satisfy the research or development engineer… - CHOICE, September 2002 Product Description Less expensive, lighter, and smaller than its electromechanical counterparts, power electronics lie at the very heart of controlling and converting electric energy, which in turn lies at the heart of making that energy useful. From household appliances to space-faring vehicles, the applications of power electronics are virtually limitless. Until now, however, the same could not be said for access to up-t...

Not only would the expert working on a specific design benefit from this handbook, but also the general reader would get a very good working knowledge on transformer design because the book covers fundamentals and magnetic material characteristics in a very clearly written, easy-to-read style. … Along with all of the practical design examples, the book is filled with clear and well-annotated illustrations and circuit schematics that provide great insight; the many references make this book a must have for anyone designing transformers or inductors. -IEEE Electrical Insulation Magazine, Feb. 2005 Product Description Extensively revised and expanded to present the state-of-the-art in the field, this Third Edition presents a practical approach to transformer and inductor design—extensively covering essential topics such as the area product, Ap, core geometry, and Kg while providing complete information on magnetic materials and core characteristics using step-by-step design...

Surge Arresters w Corona Rings Below is a sample of a specification of Surge Arrester. Some of the basic parameter are covered. You may use it as a guide in selection and specifying Surge Arresters for your specific needs. Take note that not everything is covered on the specs. Use it only as a guide. SURGE  ARRESTERS                    Brand:   Brand of Choice Class :    Station Class Installation:   Outdoor Type Voltage Rating (kV rms) : 60 MCOV Rating (kV rms) : 48 Front-of-Wave Protective Level (kV crest) :  175 Maximum Discharge Voltage (kV crest) : - 1.5 KA  125 Switching Surge Protective Level (kV crest)  @ 500 A :  117 Creepage Distance :  68 in. Insulation Withstand Voltage :     - 1.2/50 Impulse (kV Crest) 358     - 60Hz dry 60 sec (kV rms) 200 Rated Arrester Dis...

NEMA Ratings are important. It is a classification system set up by NEMA or National Electrical Manufacturers Association. NEMA is the trade association of choice for the electrical manufacturing industry. Founded in 1926 and headquartered near Washington, D.C., its approximately 450 member companies manufacture products used in the generation, transmission and distribution, control, and end-use of electricity. In non-hazardous locations, there are several different NEMA ratings for specific enclosure "types", their applications, and the environmental conditions they are designed to protect against, when completely and properly installed.  The following provides an overview of the NEMA Types. For complete definitions, descriptions, and test criteria, see the National Electrical Manufacturers Association (NEMA) Standards Publication No. 250. NEMA 1 – Enclosures constructed for indoor use to provide a degree of protection to personnel against incidental conta...

The following are sample information that may be required by a utility company in the event that a power outage occurs due to transmission and distribution lines failure; 1.1 General Information a) Date of power outage b) Location of cause c) Time occurred d) Name of caller/informant e) Name of crew who went to the location f) Cause of the power outage g) Voltage level of outage h) Extent /Affected area of the power outage i) Type of customers affected j) Number of big and contestable customers affected k) Estimated number of hours to restore power l) Number of gangs and personnel needed to restore power m) Assigned Gang and names of personnel who will do the job 1.2 Specific Information 1.2.1 138 kV Line a) Type of structure. - Wooden - Concrete - Lattice steel structure - Tapered, self –guying steel pole b) Structure’s present condition - Severely damaged, temporary restoration is nil - Severely damaged but can be temporarily restored ...

This is the right book for the "need-to-know," practical aspects of electrical power who want to get "up to speed" on the subject, regardless of education or technical training. A COMPREHENSIVE SOURCE OF TECHNICAL DETAILS ON ELECTRICAL POWER FROM GENERATION TO PRACTICAL APPLICATIONS  Reliable, low-cost electric power is a fundamental requirement for modern society, making possible such vital services as lighting, HVAC, transportation, communication, and data processing, in addition to driving motors of all sizes.  A mainstay of industrial productivity and economic prosperity, it is also essential for safeguarding human life and health. This handbook is a valuable information resource on electric power for everyone from technical professionals to students and laypeople. This compact, user-friendly edition updates and expands on the earlier edition. Its core content of power generation, distribution, lighting, wiring, motors, and project planning has...

Phase-shifting transformers help control the real power flow in transmission lines and systems interties. It is beneficial to use phase-shifting transformers in the protection of lines and transformers. Phase shifting transformers is used for protection from thermal overload and to improve transmission system stability. Phase shifting transformers enables you to control the power flow between different networks, for parallel long distance overhead-lines or for parallel cables. Phase-shifting transformer is very often the most economic approach to power flow management This is a collection of tutorials and PDF links about phase shifting transformers. Below are sites and links that discusses Phase Shifting Transformers. Phase-Shifting Transformers Phase-shifting transformers (PST) are used to control the flow of real power in transmission lines by manipulating the phase angle difference. The phase angle shift is obtained by combining the voltages from different phas...

Transmission Line Structure using Steel Pole Steel poles is fast becoming the pole of choice in construction of power lines. Most of the replacement of wooden poles have been to steel poles. Steel poles has a distinct advantage over wood poles, primarily its durability and longer life span (if properly treated, like galvanizing). This article is basically a guide on the standards and codes used in the design of steel poles. The standards presented herein are that of the US Rural Utilities Services. Codes, standards, or other documents referred to in this specification shall be considered as part of its specification. The following codes and standards are referenced when designing and fabricating steel poles to be used as transmission or distribution poles in the areas within the US Rural Utilities Services. a. American Institute of Steel Construction (AISC), Specification for the Design, Fabrication and Erection of Structural Steel for Building...

This is one of the first power systems textbooks to concentrate on modern electrical power distribution engineering. The book contains nearly 100 detailed numerical examples and about 125 problems, giving students ample exposure to and practice in solving and design of distribution systems. Dr. Gonen's book on electric power distribution is an excellent resource guide for all levels of distribution engineers. This book contains a wealth of information covering all aspects of distribution engineering from basic system planning and concepts through distribution system protection and reliability.  Considering the wealth of information "Electric Power Distribution System Engineering" covers, this book is thoughtfully laid out with excellent diagrams and very useful examples and charts. Distribution planning and design considerations are especially well noted with emphasis placed on the analysis of subtransmission lines and distribution substations through the ana...

Power Transformer The purpose of this manual is to explain how the transformer should be installed, commissioned, operated and maintained in general. In addition to the instructions given in the manual, reference should be made to : IEC-60076 Power Transformer IEC-60296 Specification for unused mineral insulating oils for Transformer & Switchgear IEC- 60137 Insulating Bushing for alternating voltage above 1000V. IEC-60354 Loading Guide for oil immersed power transformer. IEC-60364 Specification for Gas operated relays IEC-156 Method for the determination of the electric strength of insulating oils. IS-10028 Code of Practice for Installation of Transformers. IS-335 Code of Practice for Maintenance of Transformers IS-1866 Code of Practice for maintenance of Transformer oil IS-1646 Code of Practice for Electrical Installation Transformer is one of the most vital and important electrical machinery. The development of the present day power system is ver...

ACSR Conductor This is a technical paper made by the people developing the Sag 10, and it is about the compressive stress of the aluminum part of an ACSR. Consider an ACSR that has been subjected to some initial loading, following whuch the load is reduced. The unloading will follow the final stress-strain curve, and at some point the tension in the aluminum portion will go to zero. Since the aluminum will have experienced some plastic deformation, while the steel will have experienced little if any, the steel will be under tension while the aluminum goes slack. Read the rest of the technical paper on the down load link below: LINK 1 LINK 2