Learn about Electrical Insulation

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Electrical insulation, sometimes simply referred to as insulation, is material used to prevent the flow of electric current. The type of insulation material used depends largely on the application, since certain insulators (such as wire coatings) do not provide effective resistance to extremely high voltages. Some of the materials used as insulation include polyester, plastic, synthetic fibers, Nomex, Formex and braided fiberglass. Glass was once used extensively in high-voltage applications, but has largely been replaced by ceramic composites.

Insulation materials are worked in a wide range of shapes and consistencies, from thin and flexible synthetic sheathes to large ceramic and glass cylinders. The electronic devices and power solutions available in today’s industrial and commercial markets require a diverse variety of designs, and insulation fabricators utilize a multitude of machining operations to create these specialized parts. CNC machining, extruding, vertical milling, lathing, punching and forming are just a few of the methods employed by insulation manufacturers.

The effectiveness of electrical insulation changes as the temperature changes. A rise in temperature lowers insulation resistance, while a decrease in temperature will cause insulation resistance to increase. Additionally, insulation generally becomes less effective over time, whether due to environmental factors or regular wear. It is therefore prudent to periodically check the effectiveness of your insulation, especially in systems where a faulty wire or part could lead to permanent system damage.

In general, most non-metallic solids are considered insulators, since they resist the flow of electric current. Resistance is classified as the drop in voltage across a material divided by the current that passes through it. Some materials offer partial resistance, and are classified as semiconductors. Because most materials have some level of conductivity, and because most semiconductors function as insulators at low temperatures, there are relatively minor differences between the two, and are based on a material’s resistance/conductivity at room temperature.