ELECTRIC ACTUATOR WITH REGENERATIVE BRAKE CIRCUIT, ELECTRIC ROTARY VALVE FOR EMERGENCY SHUTDOWN VALVE, AND EMERGENCY SHUTDOWN SYSTEM

摘要

To provide an electric actuator with a regenerative brake circuit and an electric rotary valve for an emergency shutdown valve, which forms a regenerative brake circuit of a DC motor in an early stage to minimize over-run and prevent the occurrence of hunting when a fully-closed position limit switch is actuated, and can reduce operation torque by releasing the regenerative brake circuit of the DC motor during manual operation.SOLUTION: An electric actuator with a regenerative brake circuit is equipped with a regenerative brake switch relay 16 which disconnects a power source and a DC motor 12 when a detection means detects at least the reaching of a fully-closed position, and connects the DC motor 12 and a regenerative resistance 17 to form a regenerative brake circuit, and a relay action point threshold value circuit means 15 which controls the energization of a current passing through a coil 16a of the regenerative brake switch relay 16. The regenerative brake switch relay 16 is controlled through the relay action point threshold value circuit means 15 to form the regenerative brake circuit in an early stage.SELECTED DRAWING: Figure 1