MAGNETIC FIELD PROFILES UNDER HIGH VOLTAGE OVERHEAD POWER TRANSMISSIONS WITH UNDERBUILT DISTRIBUTION CIRCUITS

The increasing use of underbuilt lines in recent transmission projects addresses right-of-way (ROW) challenges. By assessing magnetic field intensity in these transmission and distribution network configurations, the study identifies regions with high magnetic fields that may exceed standard exposure limits, posing potential risks. This study utilizes a current-driven numerical simulation approach based on the Charge Simulation Method (CSM) and image theory, where the Biot–Savart law is adapted to compute magnetic field distributions beneath high-voltage transmission lines with underbuilt distribution systems. The approach ensures accurate evaluation of the root-mean-square (RMS) magnetic field components at conductor surfaces and at various heights above ground. Key objectives include calculating the magnetic fields at 1 meter above ground and evaluating the field at conductor surfaces. The study considers transmission line current of 500 to 1000 A and distribution line currents of 200 A, 300 A, and 400 A, respectively. The magnetic field is calculated when the underbuilt distribution line is energized and when it is de-energized and grounded. The study also examines the impact of varying distribution line heights and multiple distribution lines on magnetic field intensity. Results reveal changes in field profiles and reductions in magnetic field intensity when underbuilt distribution lines are present beneath high-voltage transmission lines. The findings highlight the effectiveness of the complex current-based simulation method and image theory in analyzing magnetic field effects and emphasize the importance of incorporating underbuilt distribution lines in high-voltage transmission system design.