The Development Of Measuring System For The Electrical Characteristics Of Low Temperature Dielectric

Superconducting power technology is a new advanced technology with wide application and huge space for development. The low temperature electrical characteristics of insulating materials, which plays an important role in superconducting power equipment, has become a critical factor influencing the operating performance and reliability of power equipment. The insulation system of many superconducting power equipments actually works in the cryogenic vacuum environment, and with the rapid development of materials science and the emerging of innovative insulating materials, studying the insulating properties of materials at the low temperature has become a necessity. The research results can not only meet the needs of engineering applications of superconducting power equipment, but also provide experimental data for dielectric theory study.To study the low temperature electrical characteristics of insulating materials, a measuring system for testing dielectrics'electrical characteristics at the low temperature has been developed in this paper, the main contributions are as follows:1. The cryogenic vacuum system, which provides cryogenic high vacuum test environment for testing the electrical characteristics of insulating materials. The test results showed that the vacuum within the system can reach as high as 10-4Pa in room temperature, and 10-5Pa in low temperature. In this test system, liquid nitrogen is used as coolant which can make the polymer films sample'temperature reach as low as 78K.2. The temperature monitoring and controlling system, which is based on Labview software platform, can monitor real-time and accurate temperatures at multiple locations, and can achieve control of sample temperature by controlling the heating device for heating components according to the set conditions. When liquid nitrogen is used as coolant, the temperature controlling system can make the polymer films sample' temperature adjustable from 78K to 300K.3. The electrode system, which allows breakdown test for polymer films of different thicknesses in cryogenic vacuum environment, can avoid the adverse effects of shrinkage deformation of materials at cryogenic temperature. Moreover, the electrode system can ensure good contact between samples and electrodes and can realize the excellent heat transmission from coolant tank to samples so as to achieve the test temperature.4. The breakdown test of PI, PET and PTFE films have been carried on using the developed test system. The test results showed that the influence of the temperature on the breakdown value is varied from different materials. The tests also show that the developed test system can maintain a reliable and stable operation in accordance with the set testing conditions.