摘要
When high-temperature superconducting(HTS)tapes in high voltage DC HTS devices are quenched,amounts of thermal bubbles are generated in liquid nitrogen(LN_(2))that will reduce the insulation strength greatly.Especially when resistive-type superconducting fault current limiters meet a short-circuit fault,the insulation strength of the LN_(2)decreased significantly due to the thermal bubbles and electrothermal pressure.Solid insulating barriers can improve the insulation strength of the LN_(2).The objective of this study is to obtain the effect of barrier thickness on the DC dielectric breakdown characteristics of LN_(2).Insulating barrier Polytetrafluoroethylene with three different thicknesses were tested.Three types of electrodes such as rod-plane,needle-plane,and planeplane were applied.The results showed that the barriers can increase the negative and positive breakdown voltage both with and without thermal bubbles in a slightly nonuniform field(SNF)and non-uniform field(NF).For the SNF,the DC breakdown voltage is higher when the barrier is thinner.The effect of the barrier thickness in the NF is lower than that in the SNF field.For the NF,the positive breakdown voltage is higher when the barrier is thicker.
基金
National Natural Science Foundation of China,Grant/Award Numbers:No.51877166,No.51907153
China Postdoctoral Innovative Talent Support Program,Grant/Award Number:BX2021233
Xi'an Association for Science and Technology Youth Talent Support Project,Grant/Award Number:095920211330
General Project of Key R&D Plan in Shaanxi Province-Industrial Field,Grant/Award Number:2021GY-119
Fundamental Research Funds for the Central Universities,Grant/Award Number:+xzy012020076。