Main indexes affecting the performance of insulating materials

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1. Insulation resistance and resistivity

Resistance is the reciprocal of conductance, and resistivity is the resistance per unit volume. The smaller the conductivity of a material, the greater its resistance, which is an inverse relationship. For insulating materials, it is always desirable to have as high a resistivity as possible.

2. Relative permittivity and dielectric loss tangent

There are two uses of insulating materials: mutual insulation of various parts of the electrical network and dielectric (energy storage) of capacitors. The former requires a small relative dielectric constant, while the latter requires a large relative dielectric constant. Both require a small dielectric loss tangent, especially for insulating materials applied at high frequency and high voltage. In order to reduce the dielectric loss, both require the use of insulating materials with small dielectric loss tangent.

3. Breakdown voltage and electrical strength

When the insulating material is damaged under a strong electric field and loses its insulating property, it becomes conductive, which is called breakdown. The voltage at breakdown is called breakdown voltage (dielectric strength). The electrical strength is the quotient of the voltage when breakdown occurs under specified conditions and the distance between the two electrodes bearing the applied voltage, that is, the breakdown voltage borne by the 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 specimen bears in the tensile test. It is the most widely used and representative test of mechanical properties of insulating materials.

5. Resistance to combustion

It refers to the ability of insulating materials to resist combustion when contacting the flame or to prevent continuous combustion when leaving the flame. With the increasing application of insulating materials, the requirements for their flammability are more important. People improve and improve the flammability of insulating materials through various means. The higher the flame resistance, the better the safety.

6. Arc resistance

The ability of insulating materials to withstand the action of electric arc along their surfaces under specified test conditions. In the test, AC high voltage and small current are used, and the arc resistance of the insulating material is judged by the time required for the conductive layer to form on the surface of the insulating material due to the arc action generated between the two electrodes by the high voltage. The greater the time value, the better the arc resistance.

7. Tightness

The sealing and isolation of oil quality and water quality are relatively good.