Electromechanical drive for actuating valves

A steam turbine with an electromechanical drive for actuating a valve of a steam turbine, the electromechanical drive comprising:

• an electromotor having a rotor with a motor axis;
• a linear unit including:
• a screw nut having a power-transmission thread;
• a piston rod engaged by said power-transmission thread, said piston rod being arranged in at least one section as a spindle, said piston rod having a longitudinal axis, said piston rod being displaceable in a longitudinal direction along said longitudinal axis;
• a clutch arranged for transmitting a rotational movement of said rotor about said motor axis onto said piston rod;
• a position pick-up configured to produce an output signal representative of a position of said piston rod in said screw nut;
• and
• an electronic control unit configured to control at least one of:
• at least one of a speed and a rotor position of said rotor about said motor axis dependent upon said output signal and a control signal;
• and
• at least one of an engagement of said clutch and a disengagement of said clutch dependent upon said control signal.