The new MWG control unit for SA multi-turn actuators and SQ part-turn actuators is available with a mechanical position indicator with considerably enhanced quality properties compared to its predecessor. By performing a reference operation during commissioning, the position indicator automatically adjusts to the valve end position. The new unit is completely compatible to the previous model and will be ready for series production at the end of this year 2015.
The functional principle of sensing the travel, recording the torque applied within the valve via absolute encoder and transforming the result via Hall sensors into electronic signal remains unchanged. These signals are processed by AC integral actuator controls. Position recording is possible even without power supply and without battery buffer. Consequently, any position change via handwheel is correctly recorded after restoring the power supply. Compared to the predecessor, the absolute encoder - the core of the control unit - comprises less components while providing identical resolution.
The mechanical position indicator of the control unit does not rely on power supply. With the new version, identification of intermediate positions has been improved. In addition, the direction of the last operation is indicated.
Automatic self-adjustment of the display means that the device housing does not have to be opened for commissioning. An absolute prerequisite is however, that the customer has specified the precise stroke range at the time of order. Should this not be the case, modification can of course be made easily at a later date. The required reduction gearing which reduces the turns per stroke for multi-turn actuators to the display range of the position indicator, forms a separate sub-assembly in combination with the position indicator. Up to nine different stroke ranges can be set via a lever without requiring to remove the control unit. The new control unit is also available for the stroke range 1 – 500 and 10 – 5,000.
