Diagnosis and Disposal Method for Thermal Failure of Busbar Connections in Low-Voltage SwitchgearYao Xia₁^, Zhu Enze^₂

Five bolted busbar connections in a 0.4 kV, 1600 A switchgear were diagnosed using synchronized load and ambient-temperature records, infrared screening, contact-resistance and torque checks, outage inspection, interface repair, and on-load retesting. At P2, normalized temperature rise and contact resistance fell from 64.7 K and 108.6 μΩ to 24.9 K and 30.8 μΩ. Across all points, the two indicators decreased by 49.2%–61.5% and 37.9%–71.6%, and torque deviations returned to the acceptance range. The method links thermal evidence to interface defects and supports field disposal of bolted busbar joints.