TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB

Transducers measure power system parameters by sampling instrument transformer secondaries. They provide a scaled, low-energy signal that represents a power system quantity that the SA interface controller can easily accept. Transducers also isolate and buffer the SA interface controller from the power system and substation environments. Transducer outputs are dc voltages or currents in the range of a few tens of volts or milliamperes. Transducers measuring power system electrical quantities are designed to be compatible with instrument transformer outputs. Potential inputs are based around 120 or 115 Vac, and current inputs accept 0 to 5 A. Many transducers can operate at levels above their normal ranges with little degradation in accuracy provided their output limits are not exceeded. Transducer input circuits share the same instrument transformers as the station metering and protection systems; thus, they must conform to the same wiring standards as any switchboard compo...

The electric utility SA system uses a variety of devices integrated into a functional package by a communications technology for the purpose of monitoring and controlling the substation. S Systems incorporate microprocessor-based intelligent electronic devices (IEDs), which provide inputs and outputs to the system. Common IEDs are protective relays, load survey and operator indicating meters, revenue meters, programmable logic controllers (PLC), and power equipment controllers of various descriptions. Other devices may also be present, dedicated to specific functions within the SA system. These may include transducers, position monitors, and clusters of interposing relays. Dedicated devices may use a controller (SA controller) or interface equipment such as a conventional remote terminal unit as a means of integration into the SA system. The SA system typically has one or more communications connections to the outside world. Common communications connections include utility...

High-voltage power electronic substations are special because of the valve rooms and buildings required for converters and controls, respectively. Insulation clearance requirements can lead to very large valve rooms (halls). The valves are connected to the yard through wall bushings. Converter transformers are often placed adjacent to the valve building, with the valve-side bushings penetrating through the walls in order to save space. The valves require controlled air temperature, humidity, and cleanness inside the valve room. Although the major part of the valve losses is handled by the valve cooling system, a fraction of the same is dissipated into the valve room and adds to its air-conditioning or ventilation load. The periodic fast switching of electronic converter and controller valves causes a wide spectrum of harmonic currents and electromagnetic fields, as well as significant audible noise. Therefore, valve rooms are usually shielded electrically with wire mesh in ...

A gas insulated substation (GIS) uses a superior dielectric gas, SF6, at moderate pressure for phase to phase and phase-to-ground insulation. The high voltage conductors, circuit breaker interrupters, switches, current transformers, and voltage transformers are in SF6 gas inside grounded metal enclosures. Sulfur hexaflouride is an inert, non-toxic, colorless, odorless, tasteless, and non-flammable gas consisting of a sulfur atom surrounded by and tightly bonded to six flourine atoms. It is about five times as dense as air. SF6 is used in GIS at pressures from 400 to 600 kPa absolute. The pressure is chosen so that the SF6 will not condense into a liquid at the lowest temperatures the equipment experiences. SF6 has two to three times the insulating ability of air at the same pressure. SF6 is about one hundred times better than air for interrupting arcs. It is the universally used interrupting medium for high voltage circuit breakers, replacing the older mediums of oil and air. ...

Bi-metal connectors Where an aluminium conductor is terminated on a copper terminal of, say, an isolator a special copper/aluminium joint is necessary to prevent the formation of a corrosion cell.  A termination of this type usually comprises of an aluminium sleeve compressed onto a copper stalk with an insulating disc separating the two surfaces which are exposed to the atmosphere. The two dissimilar materials are generally welded together by friction welding as this process ensures a better corrosion resistance at the interface. An additional protection is afforded by the use of an anticorrosion varnish.  When using such fittings it is always recommended that the aluminium component is above the copper one. Even slight traces of copper on aluminium have a disastrous effect on the aluminium material. Corrosion Since overhead lines are erected in different climatic conditions throughout the world knowledge of their performance has been built up over the yea...

It is not so much the melting point of the tungsten (which, at 3653 K, is still a relatively long way from the approx. 2800 K of the operating temperature of incandescents) that hinders the construction of more efficient incandescent lamps, but rather the increasing rate of evaporation of the filament that accompanies the increase in temperature. This initially leads to lower performance due to the blackening of the surrounding glass bulb until finally the filament burns through. The price to be paid for an increase in luminous efficiency is therefore a shorter lamp life. One technical way of preventing the blackening of the glass is the adding of halogens to the gas mixture inside the lamp. The evaporated tungsten combines with the halogen to form a metal halide, which takes on the form of a gas at the temperature in the outer section of the lamp and can therefore leave no deposits on the glass bulb. The metal halide is split into tungsten and halogen once again at the con...

When making a decision as to the best choice of devices to purchase, here are some of the questions and opportunities that should be considered: Are the components of the device compatible with the cable being spliced or terminated? Did the device pass all the tests that were specified so that it meets the requirements of the electrical system involved? Are codes applicable in the decision to use the chosen device? Review all safety requirements involved in the construction, application, and installation of the device. Will the device meet the mechanical requirements of the installation? Can the device be assembled with the tooling that is already available or are special tools required? Consider the positioning of the device. Splices are not recommended for installation at bends in the cable. Terminations are normally installed in an upright position. Other positions are possible but require special attention. Environmental conditions are of importance to...

Jointing Theory The ideal joint achieves a balanced match with the electrical, chemical, thermal, and mechanical characteristics of its associated cable. In actual practice, it is not always economically feasible to obtain a perfect match. A close match is certainly one of the objectives. The splicing or joining of two pieces of cable together can best be visualized as two terminations connected together. The most important deviation, from a theoretical view, between joints and terminations is that joints are more nearly extensions of the cable. The splice simply replaces all of the various components that were made in to a cable at the factory with field components. Both cable ends are prepared in the same manner unless it is a transition joint between say PILC and extruded cables. Instead of two lugs being attached at the center of the splice, a connector is used. At each end of the splice where the cable shielding component has been stopped, electrical stress relief...

The equipment cost of GIS is naturally higher than that of AIS due to the grounded metal enclosure, the provision of an LCC, and the high degree of factory assembly. A GIS is less expensive to install than an AIS.  The site development costs for a GIS will be much lower than for an AIS because of the much smaller area required for the GIS. The site development advantage of GIS increases as the system voltage increases because high voltage AIS take very large areas because of the long insulating distances in atmospheric air. Cost comparisons in the early days of GIS projected that, on a total installed cost basis, GIS costs would equal AIS costs at 345 kV. For higher voltages, GIS was expected to cost less than AIS. However, the cost of AIS has been reduced significantly by technical and manufacturing advances (especially for circuit breakers) over the last 30 years, but GIS equipment has not shown any cost reduction until very recently. Therefore, althou...

Now in its third edition, Introduction to Robotics by John J. Craig provides readers with real-world practicality with underlying theory presented.  With one half of the material from traditional mechanical engineering material, one fourth control theoretical material, and one fourth computer science, the book covers rigid-body transformations, forward and inverse positional kinematics, velocities and Jacobians of linkages, dynamics, linear control, non-linear control, force control methodologies, mechanical design aspects and programming of robots.  For engineers. From the Back Cover An essential book for engineers developing robotic systems, as well as anyone involved with the mechanics, control, or programming of robotic systems. Now in its third edition, the first edition of this classic text was published approximately 20 years ago. The second edition has been in print and highly successful for 16 years. The book introduces the science and technol...

Those familiar with transmission system problems and policies have developed the following list, sometimes called the “ten commandments” of transmission knowledge: Thou shall understand and consider: 1. How systems are planned and operated; 2. Effect of generation on transmission and vise versa; 3. Causes of circulating power, parallel path flow, and loop flow; 4. Differences between individual circuit capacities and transmission capacities; 5. Synchronous ac connection advantages and disadvantages; 6. Reactive power and its role; 7. Causes and consequences of blackouts; 8. Need for new technology; 9. Disincentives to building new transmission; 10. Need for special training and education.

This 5 pound book tells all about PLCs. A monumental task! Everyone involved with PLCs should have one! I wasn't expecting this much, it's a great reference manual! Outstands from all other PLC books. Explains, illustrates, and guides the reader through real life (not just theory) PLC situations that you may encounter in the industry. Its a great addition to the PLC manufacturers manual. Publisher: Industrial Text Co; 2nd edition (January 1997) Language: English ISBN-10: 094410732X ISBN-13: 978-0944107324 FREE EBOOK DOWNLOAD LINK HERE!!!

* Basic power quality strategies and methods to protect electronic systems * Nearly twice the size of the last edition--new chapters on distributed generation and benchmarking--over 200 pages of new material Dugan's book is an excellent reference on power quality. Nicely organized, starting with terms and definitions, and finishing with advice on making measurements. Very readable, with minimal use of equations, and maximum use of sketches, drawings, and graphical data. A must have for every power quality professional. This is a very good handbook for not only power quality professional,but also electrical engineers. With well organized chapters, it covered comprehensive knowledge of power quality and relevant experience of authors. I really hope it can be translated into Chinese and let more power quality professionals share this valuable resource. FREE EBOOK DOWNLOAD LINK HERE!!!

Identify and Solve Key Electric-Power-Quality Problems and Ensure Reliable Power Delivery to All Customers Power Quality in Electrical Systems equips you with the latest engineering techniques for providing power quality to all customers, and includes vital information on manufacturing, data processing, and healthcare facilities. Based on an IEEE Professional Education course, the book is a practice-oriented engineering tutorial for solving key electric-power-quality problems. This skills-building resource is designed to improve job performance by taking you step-by-step through voltage distortion…harmonic current sources…power capacitors…corrections for power-quality problems …switched-mode power supplies…uninterruptible power supplies…standby power systems…power-quality measurements…and more. Filled with 100 detailed illustrations, Power Quality in Electrical Systems enables you to: Spot and correct key electric-power-quality problems Achieve full compliance with IEEE stand...

Many professional organizations are involved in the functioning of the electric power industry. IEEE “The Institute of Electrical and Electronics Engineers, Inc. (IEEE) is a nonprofit, technical professional association of more than 377,000 individual members in 150 countries. Through its members, the IEEE is a leading authority in technical areas ranging from computer engineering, biomedical technology, and telecommunications, to electric power, aerospace, and consumer electronics, among others. The IEEE is made up of: • 10 regions; • 37 societies; • 4 councils; • Approximately 1,200 individual and joint society chapters; • 300 sections; and • 1,000 student branches are located at colleges and universities worldwide.” The Power Engineering Society is one of the 37 societies in the IEEE and has 25,000 members. “Through its technical publishing, conferences, and consensus-based standards activities, the IEEE: • Produces 30 percent of the world’s publi...

Essentially all of the world’s electric power is generated by synchronous machines. The synchronous generator has proven to be a reliable and efficientdevice for converting mechanical power to electric power.  Since the typical power system uses alternating current (60 Hz in the United States), the chief requirement of such a device is that it produces power at a controllable voltage at a constant frequency. A typical synchronous machine consists of a rotor with a field winding and a stator with a three-phase ac winding. The rotor has a dc power supply and the stator is connected to the power system through a generator step-up transformer. The turbine rotates the field at a constant speed, often as high as 3,600rpm. If the stator windings are connected to a load, current flows through the windings and the load. As the electrical load increases, the prime mover (turbine) must expend more mechanical energy to keep the rotor turning at a constant speed. Thus mechanical...

Generating units may be classified into three categories based on their mode of operation. These are: 1. Base Load; 2. Intermediate; 3. Peaking. Base load units tend to be large units with low operating costs. They are generally operated at full capacity during most of the hours that they are available. They are designed to operate for long periods of time at or near their maximum dependable capability. Their low operating costs result from their use of low-cost nuclear and coal fuels and/or lower heat rates (higher efficiencies) than other units on the system. For a typical region, base load is on the order of 40% to 60% of the annual maximum hourly load and, since this represents the amount of load that will be supplied in the region at essentially all hours, it represents perhaps 60% to 70% of the annual energy requirements of the region. Base load units are usually shut down for forced outages or maintenance only. Because of their size and complexity, these un...

HVAC Water Chillers and Cooling Towers provides fundamental principles and practical techniques for the design, application, purchase, operation, and maintenance of water chillers and cooling towers.  Written by a leading expert in the field, the book analyzes topics such as piping, water treatment, noise control, electrical service, and energy efficiency for optimal system and equipment performance and offers extensive checklists, troubleshooting strategies, and reference data, as well as recommended specifications for the procurement of new or replacement equipment. This reference also discusses proper installation and placement of chillers and cooling towers, start-up, and capacity. E-BOOK DOWNLOAD LINK HERE...

Basic tools needed to construct overhead transmission lines are as follows: 1. Conductor blocks 2. Overhead groundwire blocks 3. Catch-off blocks 4. Sagging blocks 5. Pulling lines 6. Pulling grips 7. Catch-off grips 8. Swivels 9. Running boards 10. Conductor lifting hooks 11. Hold-down blocks Conductor blocks are made in the following configurations: 1. Single conductor 2. Multiple conductor 3. Multiversal type (can be converted from bundle to single, and vice versa) 4. Helicopter Conductor blocks should be large enough to properly accommodate the conductor and be lined with a resilient liner such as neoprene or polyurethane and constructed of lightweight, high-strength materials. Sheaves should be mounted on anti-friction ball bearings to reduce the tension required in stringing and facilitate proper sagging. Conductor blocks are available for stringing single conductors or multiple conductors. Some are convertible, thus enhancing the...

An increasing number of utilities are installing metal transmission and distribution poles due to the many advantages of metal poles over wood poles.  The purpose of this white paper is to present evidence that the embedded portion of a representative steel pole offers significant grounding capability. In fact, the grounding resistance of the embedded portion of a steel pole can be shown to be lower than standard ground rods under specific conditions. In this white paper, the Numerical Electromagnetics Code (NEC-4) [1] is used to compute the grounding resistance of a variety of grounding electrodes.  NEC-4 is a method of moments [2] code originally designed for the analysis of antennas and scatterers.   NEC-4 can be used in the computation of ground resistances since it allows for conducting structures over a finitely conducting ground which may penetrate the ground.  Of particular interest is the grounding resistance of a representative steel pole s...

Transmission lines are extremely flexible structures, which can suffer from galloping under extreme environmental conditions. A better understanding of the phenomena is therefore necessary to predict occurrence and extent of this phenomenon. In this study, an aero-elastic experiment has been performed on sectional model of four-conductor transmission line considering different structural configurations. The experiment is reproduced numerically using a nonlinear FEM code, in which aerodynamic force is estimated using quasi-steady and unsteady force model. Dependence of galloping on structural configuration and efficiency of aerodynamic force prediction models is investigated in light of experiment and simulation results. Transmission lines that vary from supply to local feeders to countrywide supply to remote areas are essential part of every country’s development. These are extremely flexible structures and suffer from various types of structural instabilities. The basic conce...

VIDEO OF TRANSMISSION LINE CONDUCTORS GALLOPING

In this paper, we consider a general bi-directional relay network with two sources and N relays when neither the source nodes nor the relays know the channel state information (CSI). A joint relay selection and analog network coding using differential modulation (RS-ANC-DM) is proposed. In the proposed scheme, the two sources employ differential modulations and transmit the differential modulated symbols to all relays at the same time. The signals received at the relay are a superposition of two transmitted symbols, which we call the analog network coded symbols. Then a single relay which has minimum sum SER is selected out of N relays to forward the ANC signals to both sources. To facilitate the selection process, in this paper we also propose a simple sub-optimal Min-Max criterion for relay selection, where a single relay which minimizes the maximum SER of two source nodes is selected. Simulation results show that the proposed Min-Max selection has almost the same performance...

Micro-controllers are useful to the extent that they communicate with other devices, such as  sensors, motors, switches, keypads, displays, memory and even other micro-controllers.  Many interface methods have been developed over the years to solve the complex problem of  balancing circuit design criteria such as features, cost, size, weight, power consumption, reliability, availability, manufacturability. Many microcontroller designs typically mix multiple interfacing methods.    In a very simplistic  form, a micro-controller system can be viewed as a system that reads from (monitors) inputs,  performs processing and writes to ( controls ) outputs. Serial Buses I2C ( Inter Integrated Circuit bus ) 2-wire interface with one master and multiple slaves ( multi-master configurations possible ). Originated by Philips Semiconductor in the early 80’s to connect a microcontroller to peripheral devices in TV sets. Signals: DATA (SDA)...

Solenoids A solenoid is an electromagnet that activates a mechanical function, such as a plunger. Solenoids are used to latch safety covers closed so they can’t be opened while a machine is in operation, or to unlock the doors in your car when you push the keyless entry button on the remote. Solenoids can open and close valves in industrial processes or push the record head against the tape in a tape player. Solenoids come in many shapes and sizes, and are capable of exerting a force from less than an ounce to several pounds. There are two basic varieties: continuous duty and pulse duty. Continuous-duty solenoids are designed to be energized all the time. An application such as holding a safety cover closed would use a continuous-duty solenoid. A pulse-duty solenoid might be used for the doors in your car. Pulse-duty solenoids will overheat if left energized all the time—they are designed for intermittent operation. A pulse-duty solenoid allows a high-force solenoid to be sm...

Partial discharge measurement is an important method of assessing the quality of the insulation of power cable systems, particularly for extruded insulation materials. This article considers partial discharge from two points of view: the measurement of all partial discharges occurring within the cable system and the location of individual partial discharge sites. Measurement of Partial Discharge Perhaps the most significant factory test made on the insulation of full reels of extruded cable is the partial discharge test. This is usually done at power frequency, but can also be carried out at very low frequency and at some voltage significantly higher than normal working voltage to ground. Experience has shown that this test is a very sensitive method of detecting small imperfections in the insulation such as voids or skips in the insulation shield layer. It would therefore seem logical to repeat the test on installed cables to detect any damage done during the shipping or laying...

Oliver Heaviside is unusual - perhaps even unique - among the scientists and engineers in that he had no formal education beyond leaving school at the age of sixteen. He was somewhat deaf and lived a rather solitary life, and few people could ever claim to have known him at a personal level. His name is attached to at least two phenomena - the Heaviside step function and the Heaviside layer - in common use today. Oliver Heaviside was born on May 18, 1850, at 55 King Street in Camden Town in north London. He was the youngest of four brothers. His father, Thomas Heaviside, was a wood engraver originally from Stockton-on- Tees in north-east England, and had come to London in 1849. Camden Town in the middle of the 19th century was typical of the developing Victorian metropolitan life, with its crowded, smoke-polluted environment. He left school at sixteen, and pursued his studies at home. Then, at the age of eighteen he took a job (the only paid employment he ever had) with the G...