Flashovers

A flashover is a phenomenon that occurs in electrical systems, particularly in high-voltage environments. It describes an unintended flow of electrical current across the surface of an insulating material, rather than through its intended conductive path. This can happen due to a variety of factors, including contamination of the insulator surface, such as dust, salt, or moisture, which can create a conductive layer. Over time, this layer can dry, forming a partial conducting path. When a sufficient voltage is applied, this path can become conductive enough to allow a significant current to flow, leading to a flashover.

The process of a flashover typically begins with a partial discharge, often referred to as a corona discharge. As voltage increases, this discharge can escalate, heating the air around it. This heated air can become ionized, further increasing conductivity. If the voltage is high enough and the insulating conditions are poor, the discharge can bridge the gap across the insulator, resulting in a visible arc and a sudden, large surge of current. This arc can cause significant damage to the insulator and surrounding equipment.

Flashovers are a concern in power transmission and distribution systems, as they can lead to outages and equipment failures. Efforts to prevent flashovers include regular cleaning of insulators, designing insulators with features that resist contamination, and maintaining adequate clearances between high-voltage components and grounded structures. Understanding the conditions that lead to flashovers is crucial for ensuring the reliability and safety of electrical infrastructure.