Key Performance Indicators for Insulating Materials
Insulation Resistance and Resistivity: Resistance is the reciprocal of conductance, while resistivity represents resistance per unit volume. Materials exhibit lower conductivity with higher resistance, forming an inverse relationship. For insulating materials, maximizing resistivity is always desirable.
Relative Permittivity and Tangent of Dielectric Loss Angle: Insulating materials serve two primary purposes: Mutual insulation between components in electrical networks and as dielectric media (energy storage) in capacitors. The former requires a low relative permittivity, while the latter demands a high relative permittivity. Both applications necessitate a low tangent of the loss angle, particularly for insulating materials used at high frequencies and voltages. To minimize dielectric loss, materials with a low tangent of the loss angle are essential.
Breakdown Voltage and Electrical Strength: When an insulating material fails under a strong electric field, losing its insulating properties and becoming conductive, this is termed breakdown. The voltage at which breakdown occurs is called the breakdown voltage (dielectric strength). Electrical strength is defined as the ratio of the breakdown voltage to the distance between the two electrodes under specified conditions, representing the breakdown voltage per unit thickness. For insulating materials, higher values of breakdown voltage and electrical strength are generally preferred.
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