PSI - Issue 64

Jayathilake S. et al. / Procedia Structural Integrity 64 (2024) 137–144 Jayathilake S. et al. / Structural Integrity Procedia 00 (2024) 000–000

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1. Introduction The electricity power network is a system of interconnected components that delivers electricity power from plants to consumers. This includes both the power transmission network and the power distribution network. The power transmission network delivers generated power from plants to substations while the distribution network carries the power from substations to end consumers. Therefore, the distribution network is constructed over the urban and rural areas. This network can be constructed as either overhead or underground systems. In the Australian network, over 80% of the distribution network comprises overhead powerlines (AER, 2022). The conductor is one of the major components in the overhead power distribution network (OPDN). The conductor is a wire, or a combination of wires installed to carry electrical current without having insulation between the individual wires. Over recent years, Aluminium Conductor Steel Reinforced (ACSR) and All Aluminium Conductor (AAC) powerlines have been commonly employed in the Australian OPDN (Naranpanawe et al., 2020). The conductors in OPDN are constructed over diverse geographical and environmental conditions. This leads to various loadings including wind, thermal, rain, snow, ice, and maintenance on the power conductors. As these environmental conditions are unpredictable and diverse, the design of conductors is challenging. Usually, the design and installation are performed according to the guidelines given in the established Australian/ New Zealand standards AS/NZS7000 (2016). This Standard sets out essential guidelines for designing and constructing new overhead lines to ensure their suitability, safety, maintenance, operation, and compliance with environmental standards. The design process of the overhead lines is developed in the standard by incorporating the regulations/requirements in the electrical, structural, and mechanical fields. However, the continuous exposure to diverse weather conditions and developed mechanical stresses commence the aging phenomena within the component (Aggarwal et al., 2000). This causes sudden failures and power losses in the conductors before the service period ends. On the other hand, failure of conductors can initiate a wildfire under the fire-prone conditions in Australia (Bandara et al., 2023). Therefore, researchers have proposed different methods to understand the initiation of failure of conductors by considering the ageing parameters due to weather conditions (Liu et al., 2018; Naranpanawe et al., 2020; Vasquez et al., 2017). However, it needs improvements in the sense of failure prediction and understanding of the long-term performance of the conductor. This study aims to investigate the performance of conductors subjected to combined temperature and wind action perform within the Australian distribution network. The primary focus of this study is on ACSR and AAC powerlines, which are commonly used in the Australian OPDN. Wind and thermal loads on the conductors are taken into account, as both factors can significantly impact their performance (Zainuddin et al., 2020). The effect of elevated temperature on the aluminium and steel strands is evaluated experimentally. Furthermore, the elevated temperature effect and wind effect on the conductors are examined by using the Australian /New Zealand standard for overhead line design (AS/NZS7000, 2016). The results from experimental data are used to understand the safety performance of conductors designed according to the standard. Furthermore, a comparison of the long-term performance of ACSR and AAC was performed. 2. Conductors, loading, and their effects The conductors are typically suspended above the ground and supported by poles in OPDN. The selection of conductors for overhead power distribution depends on factors such as the voltage level of the system, the amount of current to be transmitted, and distribution distance (AS/NZS7000, 2016). The use of AAC provides the conductivity and light weight of aluminum, which makes it suitable for use in overhead power distribution lines. It provides better corrosion protection to the conductor. AAC consists of one or more strands of aluminum wire typically stranded together. ACSR creates multiple layers of aluminum strands surrounding a core formed by galvanised steel wires. The steel core provides mechanical support and helps to increase the overall strength of the conductor while reducing the sag over a long distance. This combination of materials allows ACSR conductors to efficiently transmit electricity over long distances while maintaining mechanical integrity (Riba et al., 2022; Than, 2023). The conductors need to withstand both externally and internally induced static and dynamic loads without surpassing tension thresholds. These loads include the self-weight of the conductor as a permanent load. It varies based on the type and size of the conductor. While installing the conductor, only the self-weight acts as a permanent