The circuit-breaker is a switching apparatus with three poles mounted on the frame and connected via insulating tie-rods and spring mechanisms with the shaft installed on the frame. Inside the frame there are also two opening springs, two oil buffers and spring drive connected with the shaft via the tie-rod. Insulating partitions are installed among poles. Conducting buses are connected to terminals. The shaft has a mounted plate indicating the circuit-breaker position: OPEN, CLOSE.