nsulator at the air gap and insulator surface exposed to air insulation insulation. The withstand voltage of the external insulation is closely related to the atmospheric conditions. Air gap breakdown and surface flashover are the manifestations of the loss of insulation performance. In general, the insulation performance of the air can be recovered automatically after breakdown or flashover.
The insulation of the insulator is not insulated from the direct contact with the atmosphere, and its tolerance is not independent of the atmospheric conditions. Internal insulation can be composed of solid, liquid, gas or a combination of a variety of media, internal insulation once the breakdown is often can not be automatically recovered, is a non self recovery of insulation.
The insulation performance can be recovered to the previous level automatically after the insulation failure of the self restoring insulation under the action of external voltage. Generally speaking, the external insulation is self recovery, but there are exceptions.
Non self restoring insulation under the action of external voltage insulation breakdown, insulation performance loss or can not be completely restored to the previous level of insulation, such insulation said non self recovery insulation. Generally speaking, the internal insulation is not self recovery, but there are exceptions.
Breakdown of the internal dielectric breakdown occurs, usually resulting in permanent damage to the dielectric properties of the medium.
Under the action of external voltage, the flashover occurs at the two electrodes of different potential, along with the discharge phenomena occurring at the interface between the solid medium and the atmosphere. A sufficiently strong ionization can occur on the flashover channel to generate an arc.
Basic lightning impulse insulation level under the specific conditions of self restoring insulation applied standard lightning impulse, obtained from has a 90% probability of withstand (10% discharge probability) for the standard lightning bode amplitude.
The basic operation impact insulation level is applied to the self recovery insulation under certain conditions, and the standard operation wave amplitude is obtained with a 90% tolerance probability (10% discharge probability).
The distance between the two ends of the electrode is the shortest distance between the middle medium, or the shortest distance between the electrodes.
The linear distance between the connecting conductor and the length of the supporting structure, including the connection fitting distance and the length of both ends of the insulation.
The sum of the shortest distance between the conductive parts along the insulation surface.
The leakage distance from the insulation surface which is not directly protected by the natural factors such as sunlight, wind, rain and so on. The suspension type porcelain insulator and glass insulator for protective leakage distance is refers to the insulator surface along the furrow leakage distance.