Insulating materials will undergo physical phenomena such as polarization, conductivity, medium heating and breakdown under the action of electric field. While withstanding the action of electric field, they will also be affected by many factors such as mechanics, chemistry and so on, which will lead to aging phenomenon. Therefore, many faults of electrical products often occur in the insulation part.

The aging of dielectrics refers to the phenomenon that the electrical and mechanical properties of dielectrics deteriorate gradually with the increase of time in long-term operation. Its main aging forms are electrical aging, thermal aging and environmental aging.

(1) Electrical aging. It is common in high-voltage electrical appliances. The main reason is partial discharge of insulating materials under high-voltage.

(2) thermal aging. Most of them are found in low-voltage electrical appliances, whose mechanism is that under the action of temperature, the internal components of insulating materials are oxidized, cracked and deteriorated, and hydrolyzed with water, thus gradually losing their insulating properties.

(3) Environmental aging. Also known as atmospheric aging, is due to ultraviolet radiation, ozone, salt spray, acid and alkali and other factors caused by polluting chemical aging. Among them. Ultraviolet radiation is the main factor. Ozone is produced by corona or partial discharge of electrical equipment.

Once the insulation material has aged, its insulation performance is usually not recoverable. The following methods are commonly used in engineering to prevent the aging of insulation material.

(1) Adding antioxidant in the process of making insulating material.

(2) Insulating materials for outdoor use may be added with ultraviolet absorbent or insulated from sunlight with partition.

(3) Insulation materials used in hot and humid zones can be added with anti-mildew agents.

(4) Strengthen measures to prevent partial corona and partial discharge of electrical equipment.