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Passive Components
Published in Richard C. Dorf, Circuits, Signals, and Speech and Image Processing, 2018
Michael Pecht, Pradeep Lall, Glen Ballou, C. Sankaran, Nick Angelopoulos
Transformation of power from one voltage level to another is a vital operation in any transmission, distribution, and utilization network. Normally, power is generated at a voltage that takes into consideration the cost of generators in relation to their operating voltage. Generated power is transmitted by overhead lines many miles and undergoes several voltage transformations before it is made available to the actual user. Figure 1.22 shows a typical power flow line diagram.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
The operations function includes system maintenance, construction, and service restoration. Maintenance, such as trimming trees to prevent contact with overhead lines, is important to ensure a safe and reliable system. Interruptions may be classified as momentary or permanent. A momentary interruption is one that disappears very quickly - for instance, a recloser operation due to a fault from a tree limb briefly touching an overhead conductor. Power restoration operations are required to repair damage caused by permanent interruptions.
High Voltage Cables
Published in N. H. Malik, A. A. Al-Arainy, M. I. Qureshi, Electrical Insulation in Power Systems, 2018
N. H. Malik, A. A. Al-Arainy, M. I. Qureshi
Cables have been used in transmission and distribution networks since the early days of the electrical power industry. Generally, long-distance power transmission is carried out through overhead lines. However, transmission and distribution in densely populated urban areas mostly uses underground cables. Although significantly more expensive than the overhead lines, the cables are preferred in urban areas due to safety, reliability and aesthetical considerations. As a result of developments in insulating materials and manufacturing techniques, high voltage cable technology has improved significantly over the years. With a continuous increase in the overall length of cable networks, questions regarding reliability, failure modes and diagnostics of such cables have assumed greater significance. This chapter briefly discusses various aspects of high voltage power cables with emphasis on polymeric insulated cables, which are almost exclusively being used in distribution networks in many countries. The insulation testing of high voltage cables is discussed in Chapter 12.
A review on condition assessment technologies for power distribution network infrastructure
Published in Structure and Infrastructure Engineering, 2023
Sahan Bandara, Pathmanathan Rajeev, Emad Gad
Similar to utility poles and cross-arms, overhead lines are also subjected to deterioration issues including fine cracks on insulators, corrosion of the conductors and mechanical damage to conductors induced by vibration due to wind. The insulators, often called as discs are used to support conductors of overhead lines and are subjected to deterioration due to thermal and mechanical cycling, weathering, electro-thermal causes and ionic motion (Aggarwal, Johns, Jayasinghe, & Su, 2000). The corrosion of aluminium strands is the main degradation mechanism of the conductors. The progression of corrosion with time results in a loss of the section of aluminium strands affecting the current-carrying capability and the mechanical strength of the conductor. Additionally, the alternating lift and drag forces induced by wind generates the aeolian vibration of the conductor and the resulting alternating bending stresses contribute to the conductor degradation (Zhou, Cardou, Goudreau, & Fiset, 1996). Identification of the symptoms of these failures and assessing the in-service condition of these assets are required to address the demand for safe and reliable electricity distribution minimising the involved cost.
Reliability and Sensitivity Analysis for Closed-Ring Distribution Power Systems
Published in Electric Power Components and Systems, 2022
Mohammed Wadi, Mustafa Baysal, Abdulfetah Shobole
The distribution line is one of the most sensitive components of the power distribution system to fail due to human error or environmental conditions. Overloading, vandalism, and vehicle accidents are considered as human-error reasons. Lightning, hurricanes, storms, floods, heavy rain, and snow are examples of environmental-fail reasons. The distribution line failure rate and average outage time are mainly affected by the line age, exposure rate, and weather conditions [43]. Logically, as the line gets older, it becomes more vulnerable. As shown in Figure 3(a), the age membership function consists of three functions: young, middle-age, and old. The young range is between 0 to 8 years, middle-age and old ranges are between 4 to 22, and 18 to 30 years, respectively. The distribution lines are generally constructed as overhead lines, making them vulnerable to falling trees, birds, and vehicle accidents. The exposure risk is defined by three-membership functions, low, average, and high as given in Figure 3(b). The low range is between 0 to 40%, the average range between 20 to 80%, and the high range between 60 and 100%. As aforementioned, the weather conditions can significantly affect the distribution lines. Weather conditions are classified into two categories: normal and adverse as shown in Figure 3(c). In this paper, wind speed is considered as the primary weather condition. The normal range is between 0 to 80 km/h, while the adverse range is between 30 to 100 km/h.
Identification of Fault in Invisible Underground Broken Transmission Lines
Published in IETE Journal of Research, 2021
V. Jegathesan, T. Jemima Jebaseeli, D. Jasmine David
Power cables are mostly used to transmit and distribute electrical energy in many regions, such as municipal underground power supplies, power stations, the manufacturing and mining industries, and underwater transportation [6]. They are the high-power transmission and distribution lines in a power grid. A power cable has a number of advantages over overhead lines for power transmission. It takes up less space, causes less external environmental impact, and contributes to urban revitalization. The overhead and underground transmission lines are two categories of transmission lines [7]. Because of their lower lifecycle cost and ease of maintenance, the overhead lines are more commonly used in power systems. However, the visual effect overhead lines have on landscapes and the usage may be limited. The surrounding area is unaffected by underground cables. They may be mounted in a protected environment, such as a river, where they would be protected from wind and lightning. In addition, the underground cables are less susceptible to short circuits. Even though overhead transmission grew rapidly, its drawbacks have led to greater use of underground transmission [1]. Lightning, falling trees, and insulation failure are the most common causes of overhead line faults, while physical cuts or insulation breakdown are the most common causes of underground cable faults.