- Fast, smooth and precise control from a digital circuit and proportional servo valve
- Simple time saving field set up
Quick calibration via push buttons and LED feedback and easy reversal of rotation sense (clockwise/counter clockwise) without special tools or parts change.
- Universal application
The unit can be mounted in any orientation on to any quarter turn or linear application by connection via a NAMUR or Kinetrol square interface.
- Loop powered
No separate power needed, just a 4-20mA signal plus air supply.
- Integral options - easily retrofitted modules include:
- - two wire 4-20mA isolated angle retransmit
- - mechanical or inductive position indicator switches (general or hazardous areas)
- - Clear Cone high visibility indicator
- - Threaded conduit entries or DIN plugs for external connection.
- Intrinsically safe approved options
- Weatherproof, compact and robust metal housing
- Zero backlash coupling with easily adjustable switch strikers
- Vibration and shock resistant to 4G
- Built in gauge ports/external connections
The EL positioner controls airflow to an actuator and moves it to a position determined by a 4-20mA signal and using a unique low power proportional servo valve.
The microprocessor in the loop-powered 4- 20mA position circuit reads the signal via one channel of a 12-bit A-D converter, reads the position voltage from the feedback potentiometer via the second channel of the
A-D converter, and compares the two. If it detects a position which is different from that required by the signal, it changes the output to the servo valve, in order to drive the actuator in the direction required to reach the correct position. As the actuator moves, the feedback potentiometer voltage changes and the microprocessor continually calculates the adjustments required for the servo valve in order to guide the actuator accurately into position. The microprocessor is programmed with a sophisticated but compact algorithm which allows this critical dynamic valve adjustment to be made correctly. This in turn gives optimal results with any actuator/load combination - slow or fast, low or high friction, low or high inertia. All can be optimised by tuning the PGAIN and DAMP push buttons via the positioner circuit push buttons.