Preventing Insulator Flashover – Strategies Guide Avoiding insulator flashover is essential to maintaining the safety, reliability, and efficiency of electrical power systems, from high-voltage transmission lines to substations and industrial facilities. What is Flashover? Insulator flashover occurs when a disruptive discharge (arc) travels along the surface of an insulator, bypassing its insulating function and creating a direct connection between the live conductor and ground (tower, pole, or hardware). This can result in short circuits, power outages, and equipment damage. This guide outlines key strategies for preventing insulator flashover. 1. Proper Insulator Selection and Design Choose the Right Creepage Distance Creepage distance is the shortest path along the insulator surface between the conductor and ground. In polluted environments, longer creepage paths are required. Standards such as IEC 60815 provide guidelines based on Site Pollution Severity (SPS). Use Special Insulator Designs Anti-fog or DC insulators feature deep alternating ribs and sheds, which extend the creepage path and reduce the risk of moisture forming a conductive film. Select the Right Material Polymer/Composite Insulators (silicone rubber, EPDM): Hydrophobic surfaces cause water to bead up, preventing continuous conductive layers. Superior in polluted environments. Porcelain/Glass Insulators: Hydrophilic surfaces require more maintenance. Performance decreases in wet, polluted conditions. Increase Number of Units In polluted areas, adding more discs to suspension or tension strings increases creepage distance and withstand voltage. 2. Regular and Effective Cleaning Contamination is the leading cause of flashover. Proper cleaning is critical. Washing High-pressure water jetting: Uses deionized water to safely remove contamination. Live-line washing: Specialized crews clean energized insulators without system shutdowns. Dry Cleaning Cloths, brushes, or compressed air can remove light contamination. Avoid abrasive cleaning on silicone rubber, as it may damage the surface. 3. Application of Surface Coatings Surface treatments improve insulator performance in polluted areas. Silicone Grease Provides a temporary barrier against contamination but requires periodic reapplication. RTV Silicone Coating A permanent hydrophobic layer applied by brushing or spraying. Widely used to upgrade porcelain insulators in high-pollution environments. 4. Environmental and Site Management Control Pollution Sources Reduce emissions from nearby cement plants, chemical industries, or power stations where possible. Site Selection Avoid locating substations or lines near coastlines, quarries, or industrial zones with high pollutant emissions. Vegetation Control Trim trees and vegetation to minimize organic debris and improve air circulation for faster drying. 5. Advanced Monitoring and Maintenance Proactive monitoring reduces failure risks. Visual Inspections Check for tracking, erosion, cracking, or heavy deposits. Pollution Level Measurement Regularly measure ESDD (Equivalent Salt Deposit Density) and NSDD (Non-Soluble Deposit Density) to plan cleaning schedules. UV Cameras Detect corona discharge and surface arcing—early indicators of flashover risk. Leakage Current Monitoring Sensors provide real-time data. Rising leakage current indicates increased contamination and higher flashover probability. Conclusion Preventing insulator flashover requires a multi-pronged approach: careful insulator selection, regular cleaning, protective coatings, environmental management, and proactive monitoring. By applying these strategies, utilities and industries can significantly improve the resilience and reliability of their electrical networks while reducing maintenance costs and outages.
