Working Principle：

     ALHVP smart positioner receives 4～20mA valve position setting signal from automatic control system and obtain valve position setting value through A/D conversion; meanwhile, actual valve signal can be gained through position sensor; through computing and processing of control software, the gas intake and exhaust for pneumatic actuator can be controlled so as to drive the valve position to reach the setting point.
     ALHVP smart positioner is a high-performance electric/pneumatic valve positioner based on microprocessor technology, which can overcome friction force and unbalanced force on valve spool, improve the response speed of regulating valve and achieve rapid and accurate positioning. It can not only substitute the conventional electric/pneumatic valve positioners completely, but also allow direct access to network of HART protocol, realize information exchange with control system.