On-Site Infrared Detection Methodology for Abnormal Temperature Rise in Composite Insulators of High-Voltage Transmission Lines

This study investigates how measurement distance and spatial resolution affect drone-based infrared detection (DID) of abnormal temperature rise in composite insulators, aiming to optimize field inspection parameters. Laboratory tests show that temperature rise stabilizes within ~10 minutes for artificial defects and aged housings, but requires over 20 minutes for core-rod decay-like degradation and severe bonding defects. Increasing detection distance reduces image clarity and measured temperature amplitude; excessive distance causes measurement distortion. Recommended maximum detection distances are ≤10 m for devices with 0.895 mrad and 0.68 mrad spatial resolution, and ≤20 m for 0.34 mrad resolution. An indirect distance control method based on the insulator's frame height ratio is…