Flexible in Any Position — Valve Positioners as Versatile Multi-Taskers
Another advantage is that the EMC filter module for connecting the NCS or other external sensors can be very easily retrofitted to the Sipart PS2. This eliminates the need for the customer to order a special device that cannot be used for standard applications. In short, wherever a solution is needed for automatic control of a pneumatic actuator, irrespective of the form of the actuator movement, the Sipart PS2 positioner, coupled with external sensors, offers several different approaches.
Low Air Consumption
An increasing number of plant operators are looking beyond the one–off costs when considering the claimed cost–effectiveness of positioners, and are instead examining their total cost of ownership. A fundamental component of this is the cost incurred by the compressed–air consumption of the positioner. It turns out that in most cases the biggest consumer of compressed air is not the control air that moves the actuator — all devices require the same quantity of compressed air for this purpose — but the air used by the positioner as it holds the valve at a constant position.
This is why Siemens offers an exemplary positioner with extremely low air consumption. With an intrinsic consumption of just 0.036 Nm3 per hour and allowing for typical supplementary conditions, the following annual values can be calculated for a Sipart PS2:
- energy consumption solely for generating compressed air: approximately 33 kWh;
- costs incurred solely for generating compressed air, approximately €2;
- resulting CO2 emissions: approximately 21 kg.
Compared to older positioners, this represents a potential saving of more than 90 percent.
Diagnostics and Interoperability
Particularly in new plants, communications based on fieldbuses — or at least the Hart protocol — are common. Here the Sipart PS2 excels on two fronts. First is the fact that it supports both common parameterization concepts: those based on EDDL (Electronic Device Description Language) and the FDT/DTM (Field Device Tool/Device Type Manager), respectively. Second is its proven interoperability in other control and asset management systems alongside the Siemens PCS 7 control system and Simatic PDM.
For plant operators, the issue of integration into control systems is closely linked with the additional diagnostic messages that the positioner sends to the control system and asset management system. This is where the customer can take preventive measures to generate added value by reducing costs.