Modern power distribution networks are under pressure to improve reliability, cut maintenance costs, and streamline operational safety. Conventional methods for measuring overhead line currents rely heavily on contact-based sensors—such as Current Transformers (CTs) or Hall-effect sensors connected directly to conductors. While functional, contact-based methods bring high installation costs, safety risks during manual setup, and susceptibility to electromagnetic interference (EMI). Traditional alternatives like Rogowski coils lack sensitivity over broad bandwidths, and options like Tunnel Magneto-Resistance (TMR) or Anisotropic Magneto-Resistance (AMR) are either prone to magnetic saturation or remain expensive. A promising non-contact solution uses Giant Magneto-Resistance (GMR) sensors positioned at a distance beneath overhead distribution lines.
Key Performance Insights
Relative Accuracy: The GMR non-contact monitoring system achieved 64.64% to 91.49% relative accuracy overall, with performance across most phases exceeding 80%. Linear Load Handling: Reconstructed current waveforms closely mirrored reference Hall-effect measurements, maintaining residual current margins within +/- 2 Amp.
Non-Linear / Harmonic Stress: Under non-linear loads (combining CFLs, microwave ovens, and air conditioners), odd-order harmonics increased distortion. This resulted in higher residual error on the neutral conductor (Phase N NMAE: 35.36%).
Error Factors: Deviations stem primarily from physical mounting tolerances, minor axis misalignments, and sensor hysteresis—areas targeted for post-assembly AC calibration improvements.
Reference:
M. M. Rahman Chy, M. Rifat Al Amin Khan, M. S. Mahamud, A. Islam Sifat and F. J. Stevens McFadden, "Real-time Load Current Monitoring of Overhead Lines Using GMR Sensors," 2026 IEEE/PES Transmission and Distribution Conference and Exposition (T&D), Chicago, IL, USA, 2026, pp. 1-5, doi: 10.1109/TD48022.2026.11562453.
keywords: {Current;Image sensors;Magnetic fields;Loading;Printing;Arrays;Conductors;Hall effect;Head;Sensitivity;GMR;Test Facility;MATLAB;Overhead Lines;Hall-effect Sensor},
