The Kinetrol P3 On/Off positioner consists of an electronic positioning circuit mounted in a robust all-metal enclosure, which controls a 1⁄4-turn rotary pneumatic actuator via standard on-off solenoid valves direct-mounted on the actuator’s own interface.
The P3 circuit is designed so that its assembly can be mounted inside a standard Kinetrol limit switch box (either ULS-type, or explosion proof XLS-type), using only two screws. The P3 assembly is complete with feedback potentiometer and anti-backlash gear drive, which engages with gear teeth on the limit switch coupling to read the actuator’s position.
The positioner circuit is powered by the mid-point input voltage. It functions by comparing the actual mid-point position (read by the feedback potentiometer) with the set position (set via an on-board preset, or a remote preset, or a remote 4-20mA signal). The positioner circuit uses its solid-state switched outputs to power solenoid valves which drive the actuator towards the position where the set position corresponds with the actual position. When it gets there, the solenoids are switched to hold that position.
Double acting models are available as fail-free (standard), fail-down (moves clockwise on loss of electrical power if air supply is still present) and fail-hold (holds position on loss of electrical and / or air supply) variants.