Post insulator is a special insulation control that can play an important role in overhead transmission lines. In the early years, pillar insulators were mostly used for telegraph poles. Slowly, many suspended insulators were hung on one end of the high-voltage wire connection tower to increase the creepage distance. They are usually made of silica gel or ceramics and are called insulators. Insulators play two basic roles in overhead transmission lines, namely supporting wires and preventing current from returning to the ground. These two roles must be guaranteed. Insulators should not fail due to flashover breakdown caused by changes in the environment and electrical load conditions. , Otherwise the insulator will lose its function, which will damage the use and operating life of the entire line. Six characteristics of post insulators:
1. The post insulator meets or exceeds the national and relevant standards
The post insulators all meet the requirements of GB8287.1 "Technical Conditions for High Voltage Post Porcelain Insulators" and GB12744, "Pollution-resistant Outdoor Rod Post Porcelain Insulators", and also comply with the standard IEC168 "Indoor and outdoor users of systems with a nominal voltage higher than 1000 volts" The test of porcelain or glass pillar insulators and IEC publication 815 "Guidelines for the selection of insulators under contaminated conditions".
2. The insulator has high mechanical strength, low dispersion, safe and reliable operation
3. Good low-temperature mechanical properties of insulators
In order to test the low-temperature mechanical properties of the product, the freezing test of the ZSW1-110/4 type insulator was carried out in the low-temperature laboratory of the Water Research Institute of the Songliao Water Conservancy Commission to simulate the change of outdoor winter temperature. After several temperature cycles, the test crystal was subjected to a bending failure test at a low temperature. The test results prove that the bending failure strength of the insulator at -40°C has no significant change compared with room temperature.
Outdoor rod post insulator 10～63kV.jpg
4, excellent stain resistance
The pollution resistance of insulators mainly depends on the structure of the product and the shape of the umbrella skirt. A lot of work has been done in this regard. Through design optimization, artificial pollution test optimization, and natural pollution test optimization, the insulator sheds with alternate large and small umbrellas and with ribs under the umbrella are determined after *. The insulators with rated voltages of 126kV, 252kV, bending failure load not less than 12kV and creepage ratio of 25mm/kV developed with this umbrella can withstand the highest operating phase voltage for a long time under the salt density equivalent of 0.12mg/cm2. That is to say, the creepage distance of the insulator grade III can withstand the equivalent salt density pollution of grade IV. An insulator with a rated voltage of 550kV and a creepage distance of 25mm/kV can operate for a long time under the equivalent salt density of 0.06mg/㎝2. The pollution resistance level of the insulator is leading in the country, and the salt density value of the insulator is higher than one third of similar products with the same climbing distance and equal diameter umbrella. The results of the artificial pollution withstand voltage test conducted by the Northeast Electric Power Testing and Research Institute show that the insulator with a creepage ratio of 31mm/kV has a maximum salt density of 0.25mg/cm2.
5. High level of earthquake resistance
The insulators with rated voltages of 252kV and 550kV were tested for seismic performance with an intensity of 9 at the Beijing Institute of Water Resources and Hydropower Research, and the test products were intact.
6, low radio interference
The insulator with the rated voltage of 550kV, at 1.1 times * high operating phase voltage, the radio interference is not more than 500μV, there is no visible corona on sunny days and nights, and the visible corona voltage is as high as 450kV.