2 Application
Val Controls intelligent hydraulic positioner controls almost all hydraulic, linear, rotary, single-
return (SR) and double-acting (DA) actuators on the market.
Its compact design, with few moving parts, makes it very reliable. The flexible software calibrates
automatically, it contains intern safety surveillance together with several standard flow curves. A
special flow curve is defined very simple, and the positioner’s set point and deadband can be
adjusted from the user menu.
The positioner works by comparing the control loop signal with the position feedback, it then uses
control valve signals to operate the actuator/valve to the desired position. The control loop and the
transmitter loop signal is a 4-20mA signal with HART communication. The control valve signals
are powered through the 24VDC power supply and can supply valves up to 192W, 48W each. The
position feedback from the actuator/valve can be either a potentiometer or a 4-20mA loop powered
transmitter.
The power unit controller measures the pressure in the hydraulic system and controls a hydraulic
pump unit in order to keep the pressure within a specified range. When the pressure falls below a
user defined value, the positioner will turn on the pump and keep it running until the pressure has
reached the maximum defined value. Two pressure switches can be used instead of a pressure
transmitter.
It is possible to connect temperature and level transmitter/switches to monitor the hydraulic system
and shutdown the pump if a user defined value is reached.
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