Transient Magnetic Field Detection Technology for GIS Busbars Based on a Strap-On Magnetic Sensor Array

To address electrical contact defects in plug-in contacts within Gas Insulated Switchgear (GIS) bus compartments, a contact state detection technique based on the spatial asymmetry of magnetic fields is proposed. Tunnel Magnetoresistance (TMR) sensors were encapsulated into watchband-type modular packaging. A prototype magnetic sensor array, designed for flexible deployment on the GIS bus enclosure, was developed to detect the spatial magnetic field around the GIS enclosure. Simulated GIS bus tests were conducted under conditions of insufficient insertion depth, angular misalignment, and spring relaxation to validate the detection method and construct a dataset. A neural network was employed to model the relationship between the magnetic field and the internal electrical contact state, enabling the identification of internal contact defects. Results demonstrate that the developed sensor array achieves a magnetic field measurement error lower than 0.05 Oe with a frequency response ranging from 30 Hz to 30 kHz. The standard deviation distribution index of spatial magnetic field intensity accurately reflects contact defects. The proposed magnetic field detection technique serves as a complementary method to loop resistance measurement, facilitating early warning of electrical contact defects in GIS busbars. This approach contributes to the safe and reliable operation of GIS equipment.