An arc quenching device for a three-phase electrical switchgear. The device includes a first busbar, a second busbar and a third busbar, each of a respective phase of the three-phase switchgear. The device also includes a first piston and a second piston, each of an electrically conductive material. The device also includes at least one pyrotechnical actuator arranged with the first and second pistons to axially move each of the first and second pistons if the at least one pyrotechnical actuator is fired. The first and second pistons are arranged in relation to the first, second and third busbars such that said axial movement brings the first piston into contact with both the first busbar and the second busbar, and the second piston into contact with both the first busbar and the third busbar.

An interlock apparatus according to embodiments is configured to block an operation of a third circuit breaker while a first circuit breaker and a second circuit breaker operate and include a mover and a rotator. The mover include a first connector connected to the first circuit breaker, a second connector connected to the second circuit breaker, and a central part disposed between the first connector and the second connector and is rectilinearly moved along one direction in response to operations of the first circuit breaker and the second circuit breaker. The rotator include a first engagement part engaged with to the third circuit breaker and a second engagement part engaged with the central part and be rotated around a shaft passing through the first engagement part.

An interlock apparatus according to embodiments is configured to block an operation of a third circuit breaker while a first circuit breaker and a second circuit breaker operate and include a mover and a rotator. The mover include a first connector connected to the first circuit breaker, a second connector connected to the second circuit breaker, and a central part disposed between the first connector and the second connector and is rectilinearly moved along one direction in response to operations of the first circuit breaker and the second circuit breaker. The rotator include a first engagement part engaged with to the third circuit breaker and a second engagement part engaged with the central part and be rotated around a shaft passing through the first engagement part.

An arc quenching device for a three-phase electrical switchgear. The device includes a first busbar, a second busbar and a third busbar, each of a respective phase of the three-phase switchgear. The device also includes a first piston and a second piston, each of an electrically conductive material. The device also includes at least one pyrotechnical actuator arranged with the first and second pistons to axially move each of the first and second pistons if the at least one pyrotechnical actuator is fired. The first and second pistons are arranged in relation to the first, second and third busbars such that said axial movement brings the first piston into contact with both the first busbar and the second busbar, and the second piston into contact with both the first busbar and the third busbar.