1. Insulation resistance and resistivity
Resistance is the reciprocal of conductivity, and resistivity is the resistance per unit volume. The less conductive a material is, the greater its resistance is, and the two are in a reciprocal relationship. For insulating materials, it is always hoped that the resistivity is as high as possible.
2. Relative dielectric constant and dielectric loss tangent
Insulating materials have two uses: mutual insulation of various components of the electrical network and dielectric (energy storage) of capacitors. The former requires a small relative dielectric constant, and the latter requires a large relative dielectric constant. Both require a small dielectric loss tangent, especially for insulating materials used at high frequencies and high voltages. In order to reduce dielectric loss, insulating materials with a small dielectric loss tangent are required.
3. Breakdown voltage and electrical strength
Insulating materials are destroyed under a strong electric field, losing their insulation properties and becoming conductive, which is called breakdown. The voltage at the time of breakdown is called breakdown voltage (dielectric strength). Electrical strength is the quotient of the voltage at the time of breakdown under specified conditions and the distance between the two electrodes subjected to the external voltage, that is, the breakdown voltage per unit thickness. For insulating materials, the higher the breakdown voltage and electrical strength, the better.
4. Tensile strength
It is the maximum tensile stress that the sample bears in the tensile test. It is the most widely used and representative test for the mechanical properties of insulating materials.
5. Combustion resistance
It refers to the ability of insulating materials to resist burning when in contact with flames or to prevent continued burning when leaving flames. With the increasing application of insulating materials, the requirements for their combustion resistance are more important. People use various means to improve and enhance the combustion resistance of insulating materials. The higher the combustion resistance, the better the safety.
6. Arc resistance
Under the specified test conditions, the ability of insulating materials to withstand the arc action along their surface. During the test, AC high voltage and low current are used. The arc action generated by the high voltage between the two electrodes is used to determine the arc resistance of the insulating material. The larger the time value, the better the arc resistance.
7. Sealing degree
It is better for sealing and isolation of oil and water.