Patent ID: 8596608

Claim:
A sub sea valve actuator system comprising: a piston; a cylinder assembly; a return spring; an actuator housing in which the piston, the cylinder assembly and the return spring are arranged; a hydraulic pump; an electric motor assembly, wherein the hydraulic pump and the electric motor are associated with the piston and cylinder assembly; hydraulic flow lines for hydraulic medium driving the piston and cylinder in relative displacement against a force of the return spring; a detector arranged to detect an end-of-stroke position of the piston and cylinder assembly, wherein said detector comprises at least one of: a motor current monitoring circuit unit; a hydraulic medium pressure sensor unit; a position sensor unit; and a linear variable differential transformer unit; and an electromechanical arresting mechanism is arranged to be energized for releasably arresting the return spring in a compressed state in result of the detected end-of-stroke position.