Quench-Induced Dynamic Breakdown Characteristics of $\hbox{LN}_{2}$ and $\hbox{LN}_{2}/\hbox{PPLP}$ Composite Electrical Insulation System for Superconducting Power Apparatus

In HTS power apparatus, quench due to the fault current generates dynamic electrical/thermal combined stress. This stress may induce the electric breakdown (BD) under the operating voltage. We investigated the quench-induced dynamic BD characteristics of LN
₂
. In addition we investigated the quench-induced dynamic partial discharge characteristics of LN
₂
/polypropylene laminated paper composite electrical insulation system for HTS cables. The criteria of the combined electrical/ thermal stress for the dynamic BD were obtained for both test samples, and the reduction rate of the dynamic BD criteria against the static BD criteria without thermal stress was discussed.