power systems loss

SELECTION OF CONDUCTORS FOR OVERHEAD LINE DESIGN What are the guidelines to be considered in selecting conductors for overhead line design? Economically, conductors represent between 20 to 40% of the total cost of a line; consequently their selection is of prime importance. In earlier days of electrical power transmission, copper was mainly used as the material of overhead line conductors, however with the expansion of electricity networks, several factors, such as price, weight, availability and conductivity, have virtually compelled Overhead Line Design Engineers to concentrate on aluminium based conductors, eg. AAC = All Aluminium Conductor ACRS = All Aluminium Conductor Steel Reinforcement AAAC = All Aluminium Alloy Conductor Steel conductors are still widely used as overhead earth wires and also as phase conductors on rural distribution lines, eg. SC/GZ = Galvanised Steel Conductor SC/AC = Aluminium Clad Steel Conductor Phase Conductors The conductors fulfil an electromec...

Authored by: R. F. Eaton and C. J. Kmiec ABSTRACT - As coaxial cables are used at ever higher frequencies in the Gigahertz range, cable losses become extremely important. Losses are functions of both Dk, dielectric constant, Df, tangent delta, of the polymer and the geometry of the cable construction. Control of the polymer architecture and additive package can reduce electrical losses in the cables fabricated from the polymer resulting in lower cable losses. Dk of a polymer is related a variety of chemical properties of the polymer: polarity, Tg, Tm etc. Df of a polymer is related to molecular motions of polar groups either along the polymer chain or the motion of polar molecules within the polymer matrix. We will discuss the Df contributions of the alpha, beta and gamma transition in polyethylene. Dk and Df are also functions of frequency and temperature.

Authored by: www.ep200.com Heat in the System Reducing heat in the electrical system is critical to improving power quality. Wire is the heart of the electrical distribution system. A typical facility can have tens of thousands of feet of wire throughout the facility and wire is a major source of heat. Heat prematurely degrades wire quality causing both energy losses and burnout of the wire.

BUILDING WIRES TYPES AND APPLICATION GUIDE What are the common types of wires used for building wiring installation? TW (Thermoplastic Moisture-Resistant) The TW conductors are solid or stranded annealed (soft) copper, insulated with a moisture resistant and flame retardant polyvinyl compound (PVC). TW wire is used in interior wiring at circuit voltages up to 600 volts. Maximum operating temperature is 60°C in dry or wet application. Type TW building wire is used in residential, commercial and industrial buildings for generalpurpose lighting, appliance, power, control and relay panel applications. It is used for low ampacity rated circuits. This type of wire may be installed in conduits, ducts or raceways. Type TW wire is also suitable for installations in ambient temperatures down to -10°C. THW (Thermoplastic Heat and Moisture Resistant) The THW conductors are solid or stranded annealed (soft) copper, insulated with a tough heat and moisture resistant, and flame retardant po...

MEDIUM AND HIGH VOLTAGE WIRES AND CABLES What are the types of conductors/cables used for power distribution? There is no consensus among standard governing bodies like (i.e., IEC, ANSI, IEEE, UL, NEC and others) concerning the classification of voltage level.Thus, for clarity of this manual we will utilize IEEE voltage level classifications wherein 601V to 69,000V is medium voltage and 69,001V to 230,000V is high voltage.Furthermore, conductors are also classified according to their degree of insulation covering (i.e. bare, covered, and insulated). Basically, construction of the wires and cables is the same or similar for medium and high voltage applications. Bare Conductors Bare conductorsare those without covering and primarily used for overhead power transmission and distribution application. Insulating medium is air wherein the conductors are spaced from each other and any grounded object based on the system voltage. Insulators (e.g. porcelain, glass, and polymers) are used to ...

WAYS AND MEASURES IN PROTECTING DISTRIBUTION LINE CONDUCTORS FROM DAMAGES  What are the ways in protecting line from damages that occur in transmission and distribution lines? Gentle Handling of Cable - Careful handling in the field to avoid scratches, cuts or kinks in the conductor is desirable during the field operations of paying out, stringing, and tying or clipping in. Follow Sag-Tension Charts - Sagging conductors at tensions higher than recommended increases susceptibility to aeolian vibration. Sagging in at tensions lower than recommended reduces the probability of aeolian vibration but increases susceptibility to galloping. The Use of Armor Rods on Conductors - Armor Rods are intended for clamp supports, but they can also be used at tied supports. Armor rods are effective in sacrificing their surface to abrasion instead of the conductor’s outside surface. In addition, they provide protection against electrical burning of the conductor from flashovers. Armor rods d...

COMMON LINE DAMAGE IN A DISTRIBUTION SYSTEM FEEDER LINE   What are the common of line damages that occur in transmission and distribution lines?  The cause of damages to transmission and distribution lines can be attributed to many potential reasons. Conductors are one of the most exposed electric company asset to many unfortunate events. The cost of conductors is one of the major expenses in any overhead power line construction. It is the primary component in the flow of revenue for a utility and the component most exposed to hazards. With the introduction of aluminum conductor, the vulnerability to damage increased due to its easily abraded surface. The four types of motion occurring on overhead power lines are (1) aeolian vibration, (2) galloping, (3) sway oscillation and (4) unbalanced loading. Each is independent in cause and effect. Insulator and conductor damage can be classified into four main points; where lines are seldom inspected, the first indication of damage ...

Losses in the transmission lines most especially in the overhead bare type of conductors does not only depends on the load it carries or the resistance it possesses. Although these are the major factors to consider, we can not deny the fact that the temperature also contributes a lot. Resistance of any metallic object tends to increase as temperature rises. As a result, we can say that line losses in transmission lines are directly proportional to the temperature.

Losses occurs in every transmission line all because of its inherent property of electrical resistance. Electrical lines like ACSR cable possesses resistance which is considered to be a determining factor on knowing the extent of losses it could give to the system. That is why it vital for us to know the internal properties of these conductors for us to better understand its effect to system's loss. Tables shown below are some of the commonly used conductors in an electrical system. Conductor resistance is in per kilometer basis at 60 hz.

BUNDLED CONDUCTORS IN TRANSMISSION LINE Bundling of conductors in a transmission line is a product of experts' ingenuity. In support to this post regarding bundled conductors, we will discuss here how bundling of conductors can affect the losses in the transmission lines. Bundling of conductors in the transmission lines helps lessen the effect of the two major phenomena the exist especially in voltage levels of 220kV and up namely; the CORONA effect and the SKIN effect .  Corona, also known as partial discharge, is a type of localized emission resulting from transient gaseous ionization in an insulation system when the voltage stress, i.e., voltage gradient, exceeds a critical value.   READ MORE >>> Skin Effect in AC circuit is the tendency of the current to crowd toward the outer surface. This results in a current density that is greater near the outer surface of the conductor.   READ MORE >>> Conductor bun...

In a network of electrical system, majority of the losses occurs in the lines particularly in the electrical conductors. Losses also varies in the kind of materials used to serve as a conductor whether it could be an aluminum, copper, gold, silver and so on. In the past, electric power were transmitted through the use mostly of copper conductors. Copper is rank among the most ideal metals for transmitting electricity due to its low resistivity also, of which it is second to silver. However, in the modern days, aluminum replaced copper as a main material for transmitting electricity simply because of the much lower cost and lighter weight of an aluminum conductor in contrast to a copper conductor with the same resistance. Another advantage of an aluminum is when compared to a copper with the same resistance, aluminum tends to have a larger diameter. It is an advantage because with a conductor with a relatively larger diameter the lines of electric flux originating on the conductor will ...

Transmission and Distribution in an electrical power system consists primarily with conductors and lots of conductors. Overhead power lines usually uses ACSR or Aluminum Cable Steel Reinforced. As the name describes, this cable is made up of two metallic components. An Aluminum, which is known to be an excellent conducting medium and not to mention cheaper compared to other metals with the same or similar characteristics. The other component of course is the steel which serves as the main support of the conductor since compared to an aluminum, steel has a higher tensile strength. ACSR Conductor ACSR conductors are also known for its aluminum to steel ratio (i.e. 18/1, 26/7, 45/7). This also describes the stranding of every ACSR cable. ACSRs are also known to have code words which individual has different intrisic characteristics and they are usually taken from the names of birds others are from animals. The table below shows a simple listing of different types of AC...

Bundled Conductors Bundling of conductors in transmission line has been  studied for as long as the transmission lines were first  constructed.  Bundle is define in the webster dictionary as several objects or a quantity of material gathered or bound together. As for the case of conductors in a transmission line, bundling is also a good way in minimizing power loss . An in-depth discussion of this will be tackled in the coming articles, as for now, we will discuss the general purpose this type of application is made for. 4 Conductors Bundled Creating a bundle of conductors is done by having two or more conductors per phase. This is usually applied in voltage level ranging above 230 kV. This level of voltage rating is also popularly known as EHV or extra high-voltage. If you are wondering how bundling of conductors can help reduce losses, let us first go back to the very basic of electrical study. Recall that electric current passes more through less res...