Insulator fouling law and equivalent salt density measurement time

In the process of long-term pollution accumulation on the surface of the insulator, it has experienced pollution accumulation (winter)-cleaning (rain season)-re-accumulation (winter)-re-cleaning (rain season)-this cycle goes back and forth, and the surface salt density continues to increase. Generally, it can reach a state of dynamic equilibrium after several years, and the salt density value in this state can be regarded as a saturated salt density.

According to the statistical results and experience of salt-tightness test data for many years, the accumulation of insulators on transmission lines has gradually increased from September each year and reached the maximum in March before the arrival of the second rainy season. This period is the accumulation of insulators. During the period, the salt density decreased due to the erosion of rain in spring and summer, and the process of accumulation of insulators in dry autumn began again. (1) During the accumulation period, the accumulation of dirt on the surface of the insulator increases at two rates: the surface area of ​​the insulator increases rapidly at the initial stage; the surface area of ​​the insulator increases slowly at the later stage of the accumulation.

It can be known from the law that the accumulated pollution of the insulator string changes with time, as long as the salt density value of the line is measured at the initial stage of the accumulated contamination of the insulator string, and then the maximum salt that may appear on the insulator string of the line is determined according to the rate of the insulator string If the density exceeds the salt density control value, it can be determined whether the line needs to be cleaned. It should be noted that:

(1) The test time should be selected from the end of October to the beginning of November every year. The reasons are: ① The pollution accumulation of the insulator during this period has passed a short initial accumulation process, and the measured data at this time has a strong representative; ② The measured data at this time may be estimated to exceed the salt of the line Close control values ​​can be submitted in time to apply for power outages in order to clean up before the occurrence of salt tight control values; ③ Pollution flashover accidents that occur over the years in overhead transmission lines are mainly concentrated from the end of November to February and March of the second year.

(2) The maximum salt density value If the maximum salt density value of the insulator during pollution accumulation is lower than the salt density control value for a long time under stable environment and climate conditions, it is the saturated salt density value. At this time, the cleaning cycle of the line can be appropriate Prolonged; if the value is greater than the salt density control value, the probability of insulator flashover will increase greatly.