Insulating materials, also known as dielectrics, are substances that do not conduct electricity or conduct it very slightly within the allowable voltage range. Their resistivity is typically greater than 1010 Ω·m, making them crucial in electrical engineering.
Fundamentals of Insulating Materials
Insulating materials primarily prevent the flow of current between different electrical potentials, ensuring the safe operation of electrical equipment. They possess high electrical resistivity, dielectric strength, moisture resistance, and heat resistance. These materials come in various forms, including gases, liquids, and solids. Air, often used as an insulating safety distance in transformers, is an example of a gaseous insulating material. Liquid insulating materials include mineral insulating oil and synthetic insulating oil. Solid insulating materials are further divided into organic and inorganic types. Organic solids, such as insulating paint, insulating glue, insulating paper, and plastics, are widely used in high-frequency transformers. Inorganic solids include mica, glass, and ceramics.
The key specifications of insulating materials include breakdown strength, heat resistance, insulating resistivity, voltage endurance, and mechanical stress strength. Breakdown strength refers to the voltage intensity at which the insulating material breaks down and causes a short circuit. Heat resistance measures the material’s ability to maintain reliability during long-term operation at elevated temperatures. Insulating resistivity is the resistance value of the insulating material, affected by the ambient temperature and surface conditions.
Applications of Insulating Materials
Insulating materials play a vital role in electrical equipment, providing mechanical support and fixation, arc extinction, heat dissipation, energy storage, moisture resistance, mold prevention, or improving the potential distribution of the electric field and protecting conductors. They are widely used in power generation equipment, power transmission and transformation equipment, traction locomotives, motors, electrical appliances, electronics, home appliances, communications, new energy (wind, solar, and nuclear), aerospace, and military industries.
With the continuous improvement of operating voltages and the expansion of the use of electrical products, environmental factors have an increasingly significant impact on insulation. This has led to the development of a number of multi-functional and coordinated insulation structures, such as new fiber and film composite insulation, thermal elastic insulation, sulfur hexafluoride gas and solid composite insulation, synthetic oil and film or film-paper composite insulation, and integral casting composite insulation.
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