Preventing insulator flashovers is critical to the reliability and efficiency of electrical systems. Flashovers can occur when there is a breakdown in the insulation, resulting in an unexpected discharge of electricity. They can also be caused by rust on electrical towers. Contamination-induced insulator flashovers cause frequent outages in severely contaminated areas. Lines closer to the ocean are more likely to become contaminated. Here are a few effective ways to avoid insulator flashovers:
- Semiconducting Glaze
A constant leakage current passes through the semiconducting glaze. This current warms the insulator's surface and reduces the moisture in the pollution. Furthermore, the resistive glaze creates an alternate path when dry bands form. The glaze shunts the dry bands while reducing or eliminating surface arcing. The resistive glaze performs exceptionally well near the ocean. The semi-conducting glaze is used to cover application insulators.
- Periodic cleaning.
Periodic cleaning with materials like ground corn cobs or walnut shells. This method of cleaning is effective, but cleaning the residual from the ground is costly and environmentally unfriendly. Periodic cleaning of the insulators with a high-pressure-driven abrasive material is the ideal solution.
- Covering with silicone rubber
Insulators can be coated with a thin layer of room-temperature vulcanized (RTV) silicon rubber, providing a hydrophobic, dirt-repellent surface with comparable pollution performance to non-ceramic insulators. However, after 5–10 years, the thin layer erodes, necessitating surface cleaning and reapplication. The most advanced method involves using high-pressure abrasive materials like ground corn cobs or walnut shells, and the coating is applied using standard painting techniques.
- Increasing Leakage Distance
The disadvantage of having more high voltage insulators is that both polluted and impulse flashover voltages increase. The latter reduces the effectiveness of insulation coordination due to the increased strike distance, which increases overvoltages at substations. One perfect solution is to increase the leakage distance by adding more units or using fog-type insulators.
- Periodic Washing
A large truck loaded with water and pumping equipment is used to wash the transmission lines. Trained personnel clean the insulators by directing water spray toward the strings. Substations are outfitted with permanent washing systems. High-pressure nozzles are attached to the towers, and water is supplied by a central pumping station.
- Changing from Ceramic to Non-Ceramic Insulators
Non-ceramic insulators have superior pollution performance, eliminating short-term pollution issues at the majority of sites. However, insulator aging may have an impact on long-term performance.
- Covering Insulator with Petroleum
Covering a thin layer of petroleum or silicon grease is an excellent way to reduce flashover in Insulator. Grease provides a hydrophobic surface that absorbs pollution particles. After one or two years of operation, the grease saturates the particles and needs to be replaced. This necessitates cleaning the insulator and applying the grease by hand.
Conclusion
Implementing a combination of these methods, depending on the electrical system's specific requirements and conditions, will help to effectively prevent insulator flashovers. Regular monitoring, maintenance, and adherence to industry best practices are critical to ensuring the long-term dependability of power transmission and distribution systems.
Midsun IKM, an international business development division of Midsun Group Inc., offers turnkey projects and consultation services for RTV insulator coatings, anti-corrosive silicone coatings, and Wildlife Outage Protection Products.
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