Many high-voltage applications employ hollow composite insulators with a tubular, hollow core or tube to resist the structural requirement without adding excess weight. This insulator type includes a durable silicone rubber or polymeric housing around an inner fiberglass-reinforced resin core to improve insulator performance and weather resistance. Generally, these are molded with a series of sheds (or flanges) on the outside surface which effectively makes the creepage distance much larger increasing the device’s performance in locations that are high pollution or areas of high moisture. A hollow design, unlike a solid core, will reduce the weight of the insulator overall, thus facilitating transportation and installation and providing high mechanical strength that can tolerate electrical and physical stresses. Combined with these properties, they are ideal for use in transmission lines, substations, and switchgear, where high mechanical support and reliable insulation are all important.
With the further developments in transmission and distribution infrastructure noted around the world, the composite hollow core insulator market has been growing at a significant rate. As electricity demand increases rapidly, particularly in rapidly urbanizing regions and emerging economies, utilities and grid operators are seeking reliable, high-performance solutions. The driving forces for the demand growth include the advantage of lightweight, high mechanical strength, and greater resistance to harsh environmental conditions as compared with traditional porcelain insulators. Market growth is also happening because advances in technology improve its durability and service life lowering the costs for power companies to maintain it. At the same time, the growing trend towards renewable energy and grid modernization will prompt new applications for it as they are designed to tolerate the alternative environmental conditions that are prevalent in renewable energy sites. Increasing demand for cost-effective lightweight resilient insulators in these environments continues to drive adoption.
The insulators consist of a hollow fiberglass reinforced core, coated on the outside with an insulating polymer (such as silicone rubber), with the outside surface molded into a shed-like shape. This design structure allows to have an electrical load accurately supported by a certain number of conductive parts without allowing current leakage between the latter.
The composite hollow insulator inserted in a power system prevents current flow from the high-voltage line into the structure on the ground. The polymer shell is hydrophobic, meaning it does not like water and helps reduce the risk of the surface being contaminated and forming a conductive path; as soon as it does, the polymer shell will break. Self-cleaning is also enabled by its hydrophobicity, as water droplets will roll off and carry dirt and contaminants away minimizing surface conductivity and the hazard of flashover in polluted or wet conditions.
The hollow core minimizes the weight of the insulator internally, and facilitates installation and transportation, minimizing weight and not compromising on mechanical strength. In addition, the hollow design also relieves electrical and mechanical stresses and spreads them past worn areas in the structure avoiding localized wear. The ability to withstand high voltages and mechanical loads due to this ability makes the hollow insulator a natural choice in substations and transmission lines to isolate life from grounded parts. It combines a durable, weather-resistant outer casing with a high-strength core for continuity of performance and long-term reliability under shifting operating pressures.
With strong safety features, hollow composite insulators can resist high electrical and mechanical stresses in extreme operating environments. The polymeric housing repels moisture, preventing flashover risk, even in wet, polluted conditions. The construction of lightweight, shatter-resistant construction increases durability while maintaining safety as the risk of hazardous breakage when handling or struck is minimized. Moreover, they are highly UV and thermal stress resistant, and suffer no explosive failures, resulting in a versatile, low-maintenance power system option.
