Experimental recurrence of an unreported fire risk of power cable: Discharge of bracket cable metallic grounding under coupled vibration conditions

In environments like bridges and tunnels, power cables are laid on metal brackets (hereinafter referred to as bracket cables). If the aluminum sheath and metal bracket form a metallic grounding fault, the air gap near the contact point may bear an intermittent discharge under the cable vibration, which is a potential source of cable fires. However, current research on cable grounding systems does not focus on analyzing the physical metallic grounding process. Discharge from coupled vibrations has been overlooked. This study accomplished the experimental recurrence of discharge at the metallic grounding point of cables under coupled vibration. According to the experimental observations, intermittent electric sparks and AC arc occur with the contact and separation of the aluminum sheath and the metal bracket due to vibrations. Under coupled vibration conditions, metallic grounding faults in cables pose a risk of causing cable fires.