Application of Magnetoresistive Sensors for Accurate Non-Contact Sag Measurement in Power Transmission Lines

Monitoring the sag of overhead transmission lines under varying environmental and load conditions is essential for ensuring safe operation, adequate ground clearance, and preventing conductor damage. In this study, the application of magnetoresistive sensors to non-contact sag measurement is investigated, and a novel measurement approach is proposed. First, the spatial distribution of the magnetic field and its relationship to conductor sag are examined through numerical integration and finite element simulations, providing recommendations for sensor placement. Next, a new sag measurement method is introduced and validated in multi-conductor setting simulations based on the observed linear relationship between magnetic field intensity along the tower vertical line and conductor sag. Finally, single- and multi-conductor laboratory experiments are conducted, and the results align closely with numerical predictions, demonstrating the feasibility of this approach. A comprehensive signal-to-noise ratio (SNR) analysis confirms that the observed linearity is measurable in real-world conditions. This method offers a reliable and cost-effective solution for overhead transmission line monitoring.