Abstract: An improved fluid actuating device for an electric switching apparatus such as a high-voltage power circuit breaker or the like includes an actuator for actuating the electric switching apparatus. The actuator has a cylinder and a differential piston movable in the cylinder between first and second end-positions corresponding to the open and closed positions of the switching apparatus. The differential piston has two end-faces for receiving fluid pressure force. One of the two end-faces has a surface area greater than the other one of the two end-faces. A high-pressure fluid supply supplies fluid to the two end-faces and a valve alternately interrupts and passes the fluid from the fluid supply to the one end-face whereby the differential piston is caused to move from the first end-position to the second end-position when the valve passes fluid to act upon the one end-face of the piston.

Abstract: Apparatus for controlling the drive for an hydraulically actuated high voltage power circuit breaker is disclosed. More particularly, the apparatus includes a number of position signal transmitter means each associated with a different one of the circuit breaker contact units. These means are each connected to respective freewheel clutches which are connected to the actuating member of a control switch means. The latter switch means is constructed so that it provides off commands to the breaker units only when all the transmitter means connected thereto are in an on or off position. The switch means is also continuously biased toward an off condition with the force of an energy accumulator.

Abstract: A fluid actuating device for an electric switching apparatus such as a high-voltage power circuit breaker or the like includes an actuator for actuating the electric switching apparatus. The actuator includes a cylinder and an actuator differential piston movable in the cylinder between first and second positions corresponding to the open and closed positions of the switching apparatus. The actuator differential piston has two end-faces for receiving fluid pressure force and one of the end-faces has a larger surface area than the other one of the end-faces. A pressure fluid supply supplies fluid under pressure and is connected to the actuator for continuously supplying fluid under pressure to the other one of the end-faces. A switching-valve alternately interrupts and connects the fluid from the pressure fluid supply to the one end-face of the actuator differential piston whereby the actuator differential piston is caused to move between its first and second positions.

Abstract: A fluid actuating device for an electric switching apparatus such as a high-voltage power circuit breaker or the like includes an actuator for actuating the switching apparatus. The actuator in turn is made up of a cylinder and an actuator differential piston movable in the cylinder between positions corresponding to the open and closed positions of the switching apparatus. A fluid supply provides fluid under high-pressure to the end-faces of the actuator differential piston. A main-valve arrangement includes a main-valve differential piston movable for alternately interrupting and connecting fluid from the fluid supply to one of the end-faces of the actuator differential piston whereby the actuator differential piston is caused to move between its end positions. The main-valve differential piston also has end-faces fluidly connected to the fluid supply.