Gas circuit breaker

A gas circuit breaker comprising:

• a container filled with an arc-extinguishing gas;
• a movable portion housed in the container, which includes a movable arc contact and is provided with a pressure accumulator that increases pressure of the arc-extinguishing gas;
• an opposing portion housed in the container and including an opposing arc contact, an exhaust pipe, and a shielding portion provided in the exhaust pipe in a state of allowing flow of the arc-extinguishing gas in the exhaust pipe;
• and
• a nozzle housed in the container and provided with a space in which arc discharge is generated between the movable arc contact and the opposing arc contact, wherein
• the shielding portion includes a first shielding wall intersecting with an axial direction of the exhaust pipe, and a second shielding wall having a cylindrical shape extending from the first shielding wall toward the movable portion along the axial direction of the exhaust pipe,
• the second shielding wall is provided with n through-holes (n is a natural number of 3 or more) with a space therebetween along the axial direction,
• a ratio of an opening area of the through-hole closest to the first shielding wall, of the n through-holes, to a total of respective opening areas of the n through-holes is 0.45×3/n±0.05,
• a ratio of an opening area of the through-hole closest to the opposing arc contact, of the n through-holes, to the total of respective opening areas is 0.32×3/n±0.05,
• a ratio of an opening area of the through-hole provided between the through-hole closest to the first shielding wall and the through-hole closest to the opposing arc contact, of the n through-holes, to the total of respective opening areas is (1−2.31/n)/(n−2)±0.05, and
• the arc-extinguishing gas whose pressure has been increased in the pressure accumulator flows into the space to extinguish the arc discharge, and flows into the second shielding wall.