Fluid actuating device for an electric circuit breaker

Fluid actuating device for an electric switching apparatus such as a high-voltage power circuit breaker or the like, said switching apparatus comprising first and second contacts at least one of which is movable and said fluid actuating device comprising an actuator for actuating the electric switching apparatus;

• said actuator including a cylinder, and a differential piston movable in said cylinder between first and second end-positions corresponding to the open and closed positions of said first and second contacts, said differential piston having two end-faces for receiving fluid pressure force;
• one of said two end-faces having a surface area greater than the other one of said two end-faces, high-pressure supply means for supplying fluid to said two end-faces;
• valve means for alternately interrupting and passing the fluid from said fluid supply means to said one end-face whereby said differential piston is caused to move from said first end-position to said second end-position when said valve means passes fluid to act upon said one end-face, means for reducing the volumetric flow-rate of the fluid supplied to said one end-face to a predetermined level in the course of the movement of said differential piston to said second end-position from said first end-position and before said second end-position is reached so as to cause the fluid to be continuously supplied to said one end-face at said predetermined level at the pressure of said high-pressure supply means until said end-position is reached and means for coupling said differential piston to said movable contact so as to cause said movable contact to move from a position whereat said first and second contacts are open to a position whereat said first and second contacts are closed as said piston moves from said first end-position to said second end-position.