Analysis of overhead transmission lines fusing failure due to poor contact between conductors and clamps

•Investigates formation mechanism by laboratory tests combined with simulation method.•On-site infrared temperature images were used to analyze conductor overheating fault.•This paper analyzes the heat conduction of the drain line of the transformer.•Temperature of the conductor is higher than that of the clamps.•Thermal image of the conductor shows it’s heat-producing like a equidistant helix.