Abstract: Vertical type tank 1, in which vertical type interrupters 2 for three phases are arranged, has current transformer units 10 and 20. Main sections of current transformer 12 and 22 for three phases are respectively arranged in current transformer units 10 and 20 so that the lines connecting their centers form triangle. Current-carrying conductors 3 and 4 connected to vertical type interrupter 2 are made to pass through main section 12 and 22, respectively. Each of current-carrying conductors 3 and 4 is connected to first and second conductor members 31, 41 and 32, 42, which pass through the main section and connected severally and respectively by connection conductor members 33, 34, and 43, so that the current path on the primary of the current transformer form a two-turn winding. Connection conductor members 33, 34 and 43 of each phase are arranged in the space between main section 12 and 22.