Boosting performance in the process industries with Profibus

Paul Boughton

The process industries are not driven by the need for the latest technology. Rather they are driven by the need to get more for less from their process plant. With capital and operational expenditures  being driven down, the need to get more from what they already have has never been greater.

The process industries differ from all other areas of manufacturing in terms of the complexity of the process, the severity of the process and the cost of failure. The problems and costs implications associated with the loss of a batch of snack foods pale into insignificance when compared to the loss of a batch of primary pharmaceutical product or the shutdown of an oil platform.

Improvements in process plant performance can often make the difference between survival and extinction in some of the most competitive business environments in the global economy (Fig.1). In these increasingly competitive markets, issues such as flexibility, traceability and availability have come to the fore across all sectors of the process industry.

The growth of Profibus within the process industries has been one of stealth, but its take-up has quickened with the growing realisation that, along with the technological benefits, it can also deliver a range of business benefits that can help the process industries rise to the challenge of manufacturing in the 21st century.

By delivering significant improvements in installation time, ease of operation, simplicity of maintenance, and optimised availability and performance, as well as by helping in compliance with various regulations, PROFIBUS offers a platform upon which manufacturers can build sustainable profitability, yet with the flexibility expected of modern day production processes. At the same time, by providing the ability to make additions or changes without the need for major shutdown, a plant automation strategy built on Profibus can also help to significantly boost overall performance, particularly on plants which run continuously, where downtime can costs many tens of thousands of Euros per hour.

In the area of installation and maintenance, it has been demonstrated time and again how an effectively planned network utilising Profibus DP and PA can provide savings in planning, installation, commissioning, documentation and service of up to 70percent on space and 40percent on costs. The number of components required can be reduced significantly, as can the need for multi-core cables and terminal blocks.  

Maintenance strategies can also be significantly improved thanks to the increased diagnostic data that is available, plus the added benefit of hot swappable devices.

Profibus also has the advantage over competing fieldbus technologies of allowing a greater number of devices to be utilised per segment, both in Ex and non-Ex environments. Specifically in Ex areas, the ability to hot swap devices enables plants to remain running while faulty and/or new devices are swapped/added.

For added flexibility, devices from many different manufacturers can be used, with Profibus ensuring seamless integration. This ease of integration provides a payback throughout the life of the plant, particular as new areas of plant are added. The need for any significant re-commissioning is eliminated, again improving availability and plant performance.

In the last few years, regulatory compliance has become one of the most important issues in the process sector. And the number of regulations only ever seems to go up, so the need for compliance will continue to increase over time. And with the US Food and Drug Administration looking to impose regulations which would require a maximum four hour turnaround in problem identification, the need for quicker and more effective ways of complying with legislation has never been as important. The key to meeting the demands of the regulators is to have both sufficient data and consistent data in a reliable format.

Profibus can help to ease the pain of compliance by providing a wide range of certified products and services from a variety of vendors, all with common profiles. This in itself provides the assurance not only that these components will work together, but that the operational and diagnostic data is of a consistent format. There is no need for individual interpretation or conversion of data within a host control system. In addition, Profibus also bridges the information gap between the control system and the associated field devices in a traditional 4–20mA parallel wired system as well as some competing fieldbus technologies by using a common profile at both H1 and H2 layers.

As well as aiding in regulatory compliance, data consistency and accuracy is also key to improving the performance of a plant. Once you are operating a process plant with devices which provide data based upon the same profile, the ability to interrogate, understand and develop performance changes is considerably enhanced. Today’s software tools enable all devices in a system to be accessed from a single point, with all data being managed in a central database. This in itself is a benefit when attempting to compare the performance of devices for operational and improvement purposes, and is especially important when integrating devices for diverse functions such as weighing systems, tagging systems and electrical components.

Maximising performance also depends on having clear and direct access to management information systems. The wide range of plant data, simulation data and diagnostics available from Profibus DP, PA and ProfiSafe, is all readily available in a format suitable for this higher level systems for easy analysis and effective business management.

With more and more data available to higher level systems, more and more plant operators have come to realise the potential benefits of effective asset management.

This focuses on the monitoring of all components which are critical to the successful operation of the plant, encompassing not only the valves and instruments, but also motor starters, drives, weighing systems, analytical equipment, PLCs, process controllers, safety systems, and a myriad of other components and technologies.

With fieldbus communication, the information obtainable from intelligent field devices about their own operational status and that of their immediate process environment meets many of the requirements for effective asset management.

The detailed diagnostics available from Profibus makes it possible to identify deviations between set-points and the actual plant status, enabling maintenance to be optimised.

The unique business proposition of Profibus for dramatically increasing plant performance has seen the installed base grow to over 10million nodes worldwide, making it the clear market leading technology. And predictions are for 20million nodes by 2007. The process industries will undoubtedly account for a large proportion of these new users. 

Sean Cahill is with Siemens Automation and Drives. For more information, visit www.siemens-industry.co.uk

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