Browsing by Author "Tefera, T.N."

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Cable dimension determination using Finite Element Method Magnetic (FEMM) for three-core belted and gas insulated cables
(Elsevier Ltd, 2024) Tefera, T.N.; Punekar, G.S.; Ibrahim, K.; Tuka, M.B.; Bajaj, M.
A numerical approach utilizing the Finite Element Method (FEM) based freeware Finite Element Method Magnetic (FEMM) is employed to optimize the insulation thickness to diameter ratio (‘T/d’) for a three-core belted cable, enclosed by a grounded sheath, as well as for a gas-insulated cable (GIC) with a common enclosure. The method analyzes the maximum electric field (E-field) within the cable. The minimum E-field magnitude across three critical regions where the E-field at its peak is calculated for different ‘T/d’ ratios, and the optimal ‘T/d’ is identified by selecting the maximum of these minimum values. Analogs to single-core coaxial cable, for a three-core belted cable with a radius of 1 per unit (p.u.), the best ‘T/d’ ratio is 0.80 when subjected to a 1 p.u. Peak potential. Additionally, the optimal conductor radius and conductor-to-cable center dimension for common-enclosure gas-insulated cables are verified to be 0.18 and 0.5, respectively. This study provides a first-time investigation of the best ‘T/d’ ratio for three-core belted cables and verifies CGIC cable parameters using FEMM, where no analytical solutions are available. The results are validated by comparing FEMM with analytical and Charge Simulation Method (CSM) outcomes. Hence, the FEMM provides low computational cost and reliable results compared to commercial software. Through these simulation efforts, the study re-examines the stress within the belted and gas-insulated cables and the parameters that influence it. The FEMM method allows for precise control of both conductor and sheath potentials, ensuring no potential discrepancies between the applied and calculated values across the entire range of T/d ratios. © 2024 The Author(s)
Comparative Analysis of 500 kV Double-Circuit Transmission Line Electric Field Intensity: Ethiopian Lines Compliance With ICNIRP
(Institute of Electrical and Electronics Engineers Inc., 2024) Tefera, T.N.; Punekar, G.S.; Ibrahim Yassin, K.; Tuka, M.
The high-intensity electric fields, which are in the vicinity of power transmission lines, have adverse effects on human and other living beings if they are not within the specified limits. The International Commission on Non-ionizing Radiation Protection (INCIRP) specifies guidelines for these E-fields from the perspective of public exposure at the ground level and sets it to 5 kV/m at 50 Hz. Thus, this study was aimed at analyzing and comparing the E-fields intensity of differently configured double-circuit 500 kV transmission lines at a height of 1 m above the ground plane. Charge Simulation Method (CSM) using MATLAB as a programming platform is used for this study. Among the tower configurations studied, a configuration that provided minimum E-fields with minimum ground clearance was identified. From the actual built transmission lines included in the study, vertical lines configuration produces a minimum E-fields intensity of 4.565 kV/m root mean square and fulfills the INCIRP requirement. However, triangular line configuration is the preferable configuration for 500 kV double circuit transmission lines giving the least E-fields at the ground with minimum ground clearance using optimized phase sequence arrangements irrespective of other comparative parameters. Additionally, an evaluation of these line configurations based on the distribution of the conductor surface E-fields was conducted. The study reveals that the E-fields on the surface of the transmission line conductors included in the study remains significantly below the intrinsic breakdown strength of atmospheric air. Therefore, it was anticipated that the designs will remain free from corona discharge under fair weather conditions. © 2013 IEEE.