Sti S.r.l.

Roberto Valoti

Flavio Tondolo

Mirko Coffetti

Nicola Zenoni

A device for checking the position of a mechanical element in translational or rotational motion which performs a predetermined stroke, the device being provided with a magnetic component integral with the mechanical element whose position is to be determined and a stationary magnetic sensor, the magnetic component has at least one magnetic element arranged according to a helical pattern.

Device for checking the position of an actuator

A valve positioner system with zero bleed at steady state is disclosed. The system has a pilot valve, the operation of which is controlled by an electronic circuit powered from a signaling and power connection of a positioner device. A plurality of pneumatic valves are activated and deactivated by the pilot valve to control a valve actuator. With varying configurations and arrangements of normally open or normally closed pilot valves and pneumatic valves, fail freeze and fail safe operations are contemplated. The activation and deactivation of the pilot valve is controlled by an electronic circuit that monitors a valve position signal.

Valve positioning system with bleed prevention

A fail-freeze valve positioner system is disclosed. The system has a transducer with a first type output port connectible to a valve actuator, and a second type input port receptive to a valve position signal that is proportional to an output of the first type output port. In addition, the system has a monitoring circuit that generates a pilot activation signal while predefined conditions are met. A primary piloted valve in communication with the monitoring circuit is coupled to the first valve. The first type output port is disconnected from the valve actuator while the pilot activation signal and thus the first valve are deactivated, holding the valve actuator in place.

Fail-freeze device for positioner

A method and device for controlling a process variable based upon a set point is disclosed. A process variable is measured, and a proportional term is assigned to a manipulated variable that is based upon a product of a proportional gain coefficient and an error magnitude between the process variable and the set point. An integral term is added to the manipulated variable under a first set of conditions, and a derivative term is added to the manipulated variable under a second set of conditions different from the first set of conditions. The sum of the proportional term, the integral term, and the derivative term is output, resulting in the process variable being responsively adjusted thereto.

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Seriate BG, Italy

Roberto Valoti