Patent attributes
Both improved protection against explosions and the possibility of performing diagnoses even when the I/P converter has been disconnected are to be provided by a position controller (5) for a pressure medium-operated actuating system, the controller being designed to be connected by a pneumatic line to a pneumatic drive (4)-equipped actuator (1) of an actuating element, especially an actuating element of a safety valve (2), where the actuator (1) has an electric power line (6) for controlling an I/P converter (7) according to the live-zero principle, and where the I/P converter (7) can be driven by an electrically controlled switch (10). The goal is achieved in that the switch (10) is designed to be driven by an additional circuit (11), which is connected to the power line (6) and installed in the position controller and which monitors the current in the power line (6).
