三相胶木闸刀开关 phase bakelite chopper switch

单刀三投开关 single pole three throw switch

三刀双掷开关 three-pole double-throw switch ; triple-pole double-throw ; three-pole double throw switch

三极双掷闸刀开关 three-pole double-throw knife switch

三刀单掷开关 three-pole single-throw switch

三极闸刀开关 three-pole knife switch

三刀单投开关 three-pole single-throw switch

三刀双投开关 three pole double-throw switch

三极双投刀开关 [电] triple-pole double-throw switch