Abstract: The electric circuit-breaker includes an interrupting chamber with at least one moving contact inside the chamber, the moving contact being actuated by means of a spring-loaded mechanical control mechanism so as to open or close the circuit-breaker. The control mechanism includes at least one first spring exerting a force tending to move the moving contact to open the circuit-breaker, and a second spring exerting a force tending to move the moving contact to close the circuit-breaker while loading the first spring. An additional spring is provided for exerting an additional force that is added to the force exerted by the first spring at the beginning of circuit-breaker opening. The additional spring thus accumulates some of the kinetic energy from the moving contact at the end of opening.

Abstract: The electric circuit-breaker includes an interrupting chamber with at least one moving contact inside the chamber, the moving contact being actuated by means of a spring-loaded mechanical control mechanism so as to open or close the circuit-breaker. The control mechanism includes at least one first spring exerting a force tending to move the moving contact to open the circuit-breaker, and a second spring exerting a force tending to move the moving contact to close the circuit-breaker while loading the first spring. An additional spring is provided for exerting an additional force that is added to the force exerted by the first spring at the beginning of circuit-breaker opening. The additional spring is mounted so that, before the end of circuit-breaker opening, the resultant of the force exerted by the additional spring for moving the moving contact is reversed so as to oppose the movement of the moving contact.

Abstract: A movable, substantially tubular-shaped contact element coacts with a fixed set of contacts which, in turn, possesses a rim of rated current contacts, a burn-off rim electrically connected with the rated current contacts, and an intermediate electrode arranged electrically insulated from the rated current contacts. In order to prevent, during the cut-off operation, commutation of the base point of the arc from the burn-off rim back to the contact surfaces of the rated current contacts, the burn-off rim is arranged within the rim of rated current contacts and inwardly offset with respect to their contact surfaces. In the cut-on position the burn-off rim surrounds a burn-off tip secured at the end of the movable contact element. The burn-off tip engages with the intermediate electrode. Between the contact surfaces of the rated current contacts and the burn-off rim there can be arranged an insert formed of a material which, in the presence of an arc, gives off a gas.

Abstract: A puffer interrupter has a bypass channel around the puffer piston, which channel is opened when the interrupter contacts have reached a separation greater than the maximum effective arc quenching separation.