Post insulator is a special insulation control, which can play an important role in overhead transmission line. In the early years, post insulators were mostly used for power poles. They were slowly developed at one end of the high-voltage power line connection tower. Many suspension insulators were hung to increase the creepage distance. They are usually made of silica gel or ceramics, which is called insulators. Insulators play two basic roles in overhead transmission lines, that is, supporting conductors and preventing current from returning to the ground. These two roles must be guaranteed. Insulators should not fail due to flashover and breakdown caused by changes in environmental and electrical load conditions, otherwise insulators will lose their function and damage the service life and operation life of the whole line. Six characteristics of post insulator:
1. The post insulator meets or exceeds the national and relevant standards
All post insulators comply with gb8287 1 the provisions of technical conditions for high voltage Post Porcelain Insulators and gb12744, pollution resistant outdoor rod post porcelain insulators, also comply with the provisions of iec168 test of indoor and outdoor porcelain or glass post insulators for systems with nominal voltage higher than 1000 V and IEC publication 815 guide for selection of insulators under polluted conditions.
2. The insulator has high mechanical strength, low dispersion and safe and reliable operation
3. The insulator has good low-temperature mechanical properties
In order to test the low-temperature mechanical performance of the product, the freezing test of zsw1-110 / 4 insulator was carried out in the low-temperature laboratory of the Institute of water science of Songliao water conservancy commission to simulate the change of outdoor temperature in winter. After several temperature cycles, the test crystal is subjected to bending failure test at low temperature. The test results show that the bending failure strength of insulators at - 40 ℃ has no obvious change compared with room temperature.
4. Excellent stain resistance
The pollution resistance of insulators mainly depends on the structure of products and the shape of 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 umbrella skirt with large and small umbrella phases and ribs under the umbrella is determined. The insulators with rated voltage of 126kV and 252kV, bending failure load of not less than 12kV and creepage specific distance of 25mm / kV developed with the umbrella skirt can withstand * high operating phase voltage for a long time under the equivalent salt density of 0.12mg/cm2, that is, the creepage distance of insulator level III, and can withstand the equivalent salt density pollution of level IV. Insulators with rated voltage of 550kV and creepage specific distance of 25mm / kV can operate for a long time under the equivalent salt density of 0.06mg/cm2. The pollution resistance level of insulator is leading in China. Its equivalent salt density is one third higher than that of similar products with the same climbing distance and equal diameter umbrella skirt. The artificial pollution withstand voltage test of insulation is carried out by northeast electric power test and Research Institute. The results show that the withstand * high salt density of insulator with creepage specific distance of 31mm / kV is 0.25mg/cm2.
5. High earthquake resistance level
The insulators with rated voltage of 252kV and 550kV were tested for seismic resistance with intensity of 9 in Beijing water resources and Hydropower Research Institute, and the results showed that the test objects were intact.
6. Low radio interference
For insulators with rated voltage of 550kV, the radio interference generated under 1.1 times * high operating phase voltage shall not be greater than 500 μ 5. Corona voltage is up to 450kv in sunny days and visible at night.
