A Master of all Positions
Sipart PS 2
Today, plant operators and their suppliers in the process industry need to meet two sets of requirements. On one side are the different requirements of the process applications, which demand a high degree of variety and feature flexibility from the process devices. On the other side, standardization and easy inventory management are gaining significance, especially in larger plants. There are also the typical general device requirements: easy operation, universal application, and low maintenance with respect to cost and time. And every user has one request with regard to installation, commissioning, and operation: the device must be cost-effective.
Of course, there are product areas in which all of these requirements can be integrated quite well. But what is the state of things when it comes to automating actuators in the process?
Valves that control the flow of process liquids and gases in order to regulate variables such as pressure, temperature, or flow can be found in all process industries. They are a fundamental part of automated process plants and are operated by various actuator types. These may be hydraulic or electrical, for example. Pneumatic actuators, however, account for the vast majority. It is not only the actuators and valves that face various challenges but, more than ever, the specific field device that is responsible for making the overall application an automated application: the positioner. These challenges include the following:
- Various actuator movements and ranges
- Manufacturer-specific standards
- Special applications
- Control or simple on/off operation
- Quick and easy commissioning
- Fast response times but precise control
- Proactive reception of information on wear and application status
Despite the different requirements of different devices, it is not necessary to resort to different suppliers as well. Both sets of requirements described above, as well as further requirements, can be perfectly combined.
Easy installation and set-up
A particular advantage of the Sipart PS2 positioner is its universal application. This requires a high degree of flexibility as well as mounting options for various actuator and valve applications for a wide lifting or rotary range.This requirement is provided for with more than 400 mounting kits, which allow the mounting of the device to standard actuators, such as rotary actuators according to the VDI/VDE 3845 standard or linear actuators according to IEC 60 534-6-1 (NAMUR), or to various nonstandard manufacturer-specific actuators.
The subsequent set-up takes only a few minutes. This is made possible by the easy and direct operation of the device with push buttons and display and the adjustable slip clutch, which ensures the smooth flow of the initialization process without costly removal and reinstallation of the device. The device “learns” the proper application settings and thus makes the best possible adjustments for the relevant requirements. If, over time, changes should result from environmental impact or wear, the positioner adapts to the new requirements and alerts the operator about the change – via HART, Profibus PA, Foundation Fieldbus, or digital output.
Flexibility for special applications or remote versions
But there’s more: When it comes to atypical applications for the positioner, such as with pneumatic cylinders, the positioner benefits from its flexibility. Thanks to its modular construction and expandability, the device can be connected to external position measuring systems. The positioner is not affected by the principle the external sensor is based on (e.g., contacting or noncontacting) or whether it is a potentiometer, a current signal, or a voltage value. All these variants of external sensors, whether external or incorporated within the actuator component – for example, in the pneumatic cylinder – can be connected to the EMC filter module.Thus, challenging applications are resolved very easily, where direct mounting of the positioner is not possible due to the application environment (e.g., extremely high temperatures), location, or actuator design, or the use of an external sensor simply represents a more elegant and superior solution.
Best practice
In the past, the failure of level sensors during slurry-mixture processing at the LKAB iron ore processor caused the slurry to completely cover the positioner as well as the control valve mounted under the tanks. The result: various positioners had to be completely replaced. Using a remote version proved to be the solution here. A Liner potentiometer on the actuator is used for position detection and is connected to the Sipart PS2 positioner via the EMC filter module, where it passes on the current position information. The positioners themselves are separated and built into a cabinet, where they are removed from any critical unwanted influences.Especially in applications with extreme vibrations, caused by vapour shocks, for example, the Sipart PS2 will excel. The current valve position is detected by the noncontacting sensor (NCS) based on the giant magnetoresistance (GMR) effect using magnetic field lines. Compared to other methods that depend on the field strength and are therefore more adversely affected by it and by the effects of temperature, the GMR principle offers a further advantage: a greater distance is possible between the sensor and magnets. The compact construction and the GMR principle of the IP68-compliant and wear-free NCS are suited for challenging applications where conventional mounting solutions reach their limits. Thanks to its modular design, the Sipart PS2 positioner can easily be connected to the NCS.
Vibrations are especially typical of applications in the pulp and paper industry. This is also the case at the Norske Skog plant. Instead of repeatedly having to replace different positioners due to wear on mechanical position interfaces, an NCS is used. Now, the positioner can be installed externally, and the contactless position measuring of the NCS saves time and costs.
Finally, the EMC filter module that allows the NCS or other external sensors to be connected to the Sipart PS2 positioner can be easily retrofitted without ordering a customized device that cannot be used for standard applications.
In other words, whenever in need of an automated control for a pneumatic actuator, regardless of the actuator motion, Sipart PS2, along with external sensors, will provide the solution.
Low air consumption
When it comes to cost-effectiveness claims for positioners, more and more plant operators are looking beyond one-time purchase expenses and considering total cost of ownership. For positioners, compressed air consumption is the main consideration here. Effectively reducing compressed air consumption is not simply a case of turning the usual setting screws, e.g. for optimizing compressor technology, renewing the compressed air distribution network, etc. The control-air necessary to move the actuator is not the main consumer of compressed air. Here, all devices require approximately the same amount of compressed air. Why then, should a positioner consume large amounts of compressed air when it only keeps the position of the actuator constant?For this reason, Siemens has developed a positioner with extremely low air consumption. For example, with a power consumption of only 0.036 Nm3/hr, and considering appropriate typical boundary conditions,1 the following values are calculated for a Sipart PS2 for one year:
- Energy consumption for the production of compressed air of approximately 33 kWh
- Costs of approximately €2 incurred for the generation of compressed air
- CO2 emissions incurred of about 21 kg
Diagnostics and interoperability
Fieldbus or HART communication is being increasingly adopted for new plants. The Sipart PS2 supports the two most widely used parameterization concepts – EDD (Enhanced Device Description), which is based on EDDL (Electronic Device Description Language), and FDT/DTM (Field Device Tool / Device Type Manager) – and offers certified interoperability with other control and asset management systems in addition to the Siemens PCS 7 process control system and Simatic PDM.Integration in control systems results in additional diagnostic messages for plant operators, which the positioner transmits to the process control system and asset management system. It is here that customers can generate added value for their processes in terms of cost savings through preventive measures.
The standard version of the Sipart PS2 includes extensive diagnostic functions. It provides reliable diagnostic information via the positioner and its environment – that is, the valve and actuator. Thus, measures can be taken before a serious valve or actuator failure occurs, to prevent an impending plant shutdown, which is particularly important for safety valves.
The diagnostic features include:
- Pneumatic leakage
- Valve stiffness
- Static friction in the stuffing box
- Wear of the valve seat or valve plug
- Deposits or caking on the valve seat or cone
- Histograms, trends
- Temperature measurement, stroke counters, etc.
Conclusion:
Plant engineering companies and operators could not ask for easier inventory management than that provided by the Sipart PS2; the product number of the standard device always remains the same, whether for linear or rotary actuators, large or small ranges, throttling or on/off valves, manufacturer-specific actuators or applications with external sensors. Precise control or additional diagnostic features along with PST – everything is covered by this flexible all-rounder and the extensive functionality contained in the standard expandable modules and wide range of available mounting kits.Calculations based on:
- assumed specific CO2 emission of 631 CO2 g/kWh
- assumed electricity price of €0.06/kWh
average specific compressor power of 6.38kW min/m3 across various industries using “Specific Power Output of a Compressor Unit at Full Load” (141 comparison values, mean value), Verband Deutscher Maschinen- und Anlagenbau (Fachverband Drucklufttechnik), the Association of German Machinery and Plant Construction (Professional Association of Compressed Air Technology)
info:
Jual positioner
jual positioner siemens
jual positioner PS2
