power systems loss

ACCR versus ACSR Customer demand for power grows, renewable generators wait for interconnection, and intermittent resources demand more flexibility from aging infrastructure. Yet dense populations, environmental concerns, permitting requirements, and land scarcity intensify the schedule, budget and regulatory risks of building or rebuilding lines. To solve these challenges, 3M developed Aluminum Conductor Composite Reinforced (3M™ CCR). 3M ACCR is an advanced transmission conductor designed to replace ACSR or ACSS on existing structures at the same tensions and clearances, giving you up to twice the capacity without the risks of a major construction project. Your line is in service fast, within budget, and with minimal environmental impacts. And the available trapwire options may help improve the line’s efficiency. To know more about 3M's ACCR, please their product catalogue. ACCR 3M Catalogue

Short Comparison between using wooden arms vs. steel arms in power transmission system. Wooden crossarms used in power transmission system are lower in cost than steel arms of the same strength and, aside from the shorter life, the possibility of being shattered by lightning, and the risk of burning due to leakage current at 345kV and above, are satisfactory. On wood pole construction, the advantages of steel arms - resistance to lightning damage and longer life - are not usually sufficient to offset the insulation strength of wood crossarms.

PROBLEM:   A 230kV transmission line has impedance of 50 angle 78 ohms and a capacitive reactance of 1200ohms. It transmits the power of a base load plant. On a certain dry season the sending end power is 100MW at 235kV and 95% power factor continuously for a period of one month. If cost of generation is 1.3dollars per kW-hr, what is the cost of the line losses for the one month period? SOLUTION: In analyzing this problem, we assume a nominal pi equivalent circuit. Also, assume the sending voltage as the reference and with a lagging power factor.  Nominal pi equivalent circuit

PROBLEM: A 15MW, 132kV, 80% power factor three phase load is to be served by a transmission line having conductors whose resistance is 0.5ohm/km. if the losses on the line shall not exceed 4.5%, how long must this line be? SOLUTION: To better understand the problem,let us first draw the figure that the problem would like to emphasize.

PROBLEM:   A 10-km, three phase transmission line delivers power to a load rated 2000kW, 6.9kV and at 80% lagging power factor. The resistance and reactance of each line are 0.2 and 1.2 ohms per kilometer, respectively. What percentage of the power generated is lost in the transmission line? SOLUTION: Similar to the previous problem , we should first draw the figure for us to understand clearly what is required for us to solve.

PROBLEM:  A 3-kilometer, 336ACSR, 3-wire short transmission line has an impedance of 2 + j5 ohms per wire. At the receiving end, a balanced 3-phase load and capacitor bank draws 3000kVA, 0.71 power factor lagging and 600kVAR respectively at 8000 volts per phase to neutral. Determine the power loss of the transmission line. SOLUTION: The first thing that we should do in analyzing any problem is to illustrate our interpretation of the problem into a figure which will make us better understand what is needed.

This guide publication is a reference containing fundamental engineering guidelines and basic recommendations on structural and electrical aspects of transmission line design, as well as explanations and illustrations. The many cross-references and examples should be of great benefit to engineers performing design work for RUS borrower transmission lines. The guide should be particularly helpful to relatively inexperienced engineers beginning their careers in transmission line design.

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.

Corona Loss Power lost due to corona process. On overhead power lines, this loss is expressed in watts per meter (W/m) or kilowatts per kilometer (kW/km). Corona A luminous discharge due to ionization of the air surrounding an electrode caused by a voltage gradient exceeding a certain critical value. Corona, Overhead Power Lines Corona occurring at the surfaces of power-line conductors and their fittings under the positive or negative polarity of the power-line voltage.

The objective of this IEEE standard entitled Standard Definition of Terms Relating to Corona and Field Effects of Overhead Power Lines is to obtain uniformity in the use of terms relating to the areas of corona and the electromagnetic environment of power lines. Its scope is to define the most widely used terms specific to or associated with overhead power-line corona and fields. Here, we are focus more on terms that are relevant to Power System's Loss topic like corona and electric fields that can influence the level of losses in a transmission line. For a complete access on the said standard, you can refer to the link below for the pdf copy.

The essential textbook for electrical engineering students and professionals-now in a valuable new edition. The increasing use of high-speed digital technology requires that all electrical engineers have a working knowledge of transmission lines. However, because of the introduction of computer engineering courses into already-crowded four-year undergraduate programs, the transmission line courses in many electrical engineering programs have been relegated to a senior technical elective, if offered at all.

IEEE Std 524 of 2003 entitled IEEE Guide to the Installation of Overhead Transmission Line Conductors’ scope is focused in providing general recommendations in the selection of tools, equipments and methods that have been found to be practical for the stringing of overhead groundwires and overhead transmission line conductors. The standard also provides a comprehensive list of definitions for equipment and tools used in stringing and for stringing terms commonly employed.

The following links are some of my collected references which tackles losses in the transmission lines. This can be a good source for additional knowledge regarding our quest to better understand the nature of losses in every power system. This is for you to have no hard time searching the net.

How to compute for the losses in transmission lines? Losses in the transmission lines can be determined less complicated compared to transformers and  distribution systems . The basic computation of it usually surrounds to the fundamentals of ohm's law . Due to the simplicity of the transmission line configuration, solving for its line losses requires no advance knowledge in any electrical principles. However, there are also portion of these line losses that better understanding is necessary. 

System Voltages in Transmission Lines Table shown is the standard system voltages from ANSI standards C84 and C92.2 According to ANSI standards C84 and C92.2, system voltages are recommend to be within the table shown below. 345kV, 500kV and 765kV are considered to be in the Extra High Voltage (EHV) level. The choice of system voltage is in the decision of the utility. However, some points needs to be considered in choosing such, like voltage economics, conductors, distances, equipments, etc.

Transmission System Requirements Listed below are the typical points to be considered before starting or even operating an Electrical Power System. These factors can be best categorized into three main points; Electrical Design, Mechanical Design & Structural Design.

Structures in Transmission Lines Mechanical support for transmission lines serves a definite purpose in the system especially in overhead lines Transmission line structures obviously is a very important part in every overhead bulk power transmission lines. It's a support for ground faults protection, insulation, and of course for conductors. The variation of these overhead line structures almost depends on the imagination of the structural designer. Nevertheless, the most common classification of transmission line structures known are made up of either poles (concrete, wood or steel)  or lattices towers. Also, the shapes and sizes of the structures depends on the type of line. The reliability and stability of transmission most of the depends on the performance of these supports especially during odd weathers. Many factors are considered in designing a transmission line structure one of these is the mechanical and electrical requirements to be complied with. Not only that it s

Transmission and Distribution Electrical Engineering This books is more of for the engineers and electrical  practitioners unlike with student texts that are more on theory .

CHECK THIS BOOK OUT! For further detailed study of Power Transmission Lines, you can download this book.

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.