单极-单极变换曲线
pole-pole transformed curve
三极双掷闸刀开关
three-pole double-throw knife switch
胶盖瓷底闸刀开关
bakelite cover porcelain base knife switch
chopper switch with bakelete lid and porcelain bottom
bakelite-cover porcelain-base knife switch
模型箱闸刀开关
mouldcase fused knife switch
双闸刀开关
double-bladed knife switch