134 / 2024-04-14 16:54:05

Barrier Effect on the Breakdown Characteristics of DC Resistive-type Superconducting Fault Current Limiters

Barrier effect,Liquid nitrogen,breakdown characteristic,Superconducting fault current limiters

Liquid Nitrogen in not only the cooling but also the insulation media for the resistive-type superconducting fault current limiters (R-SFCL). However, when the R-SFCL was quenched, a lot of bubbles will be appeared. The breakdown characteristics will be decreased due to the bubbles. An insulation barrier can improve the insulation strength of the R-SFCLs. The objective of this paper is to study the barrier effect on the breakdown characteristics of the R-SFCLs. In the experiment, a superconducting coil was in series in the large current source. The high voltage source was connected with the stainless steel Dewar. An insulation barrier was placed between the superconducting coils and the Dewar. Firstly, a high DC voltage was applied to the Dewar and kept at a constant value below the static breakdown level (U_LN2). Then, the prospective current was applied to the superconducting coil and the superconducting tapes were quenched. The dynamic breakdown of the LN₂ was induced by the thermal bubbles during the quenching. The breakdown voltage U_BLN, the current of the superconducting coil I_sc and the voltage cross the superconducting coil U_vc were recorded by a digital oscilloscope. The prospective current was set as 2000 A. For each condition, six tests were done. The 50% breakdown voltage were obtained by up and down method. The results show that when the prospective current was 2000 A, the breakdown voltage of the R-SFCL with the insulation barrier is 1.21 times that of the R-SFCL without the insulation barrier. The results can be used to guide the insulation design of the R-SFCLs.