Is wireless ready for process control?

26 April 2011

Wireless is now an accepted technology for process monitoring applications. However, is it ready to take on the challenge of process control too? Suzanne Gill reports.

So, is wireless technology ready for use in process control applications? Bob Karschnia, VP of wireless Rosemount Measurement Division at Emerson Process Management gave an unequivocal reply: “Yes. People are already using wireless technology for control purposes in the process environment.” He backed up this statement by offering details about the first Emerson customer who has actually replaced an existing wired solution with a wireless one (see panel in this article for the complete application details). The wireless control solution in this instance, has proven to be more secure than the original wired solution and has provided some impressive operational improvements.

Traditionally, wireless solutions have been used in monitoring applications where it was not possible to install a wired solution. “This has given people confidence in the system,” said Karschnia. “Wireless has moved much more into the mainstream for monitoring purposes and I believe that these same steps will happen with control… It will first start to become prominent in control applications where there is no choice but to use a wireless solution. It will take a couple of years but people are doing it already.”

Ray Rogowski, director of global wireless business for Honeywell Process Solutions says that wireless technology is not a new phenomenon in process control applications. He said: “Honeywell has been selling industrial wireless since 2003. We are seeing a greater number of scenarios where wireless solutions are being used for personal safety and safety management reasons and for plantwide security to mobile operations.”

He goes on to say: “In the safety and security arena, many Honeywell customers are using wireless technology to meet new and stricter security, environmental and safety regulations. Wireless allows them to meet these regulations in a reliable cost effective manner that was not previously available. We have demonstrated that the OneWireless Equipment Health Monitoring solution can improve uptime of rotating equipment by 1% which translates into huge cost savings. In the area of efficiency, we have customers using wireless transmitters for monitoring, critical monitoring and open loop control with some piloting closed loop control based on wireless I/O. These devices are used in a variety of applications such as furnace or tank farm optimization.”

Security issues
On the subject of wireless security, Kurk Polzer, manager business development Sensors and Communications at Siemens, said: “Today, there are two major wireless technologies being used – at field level WirelessHART, and at higher levels in the automation pyramid there is Industrial Wireless LAN (IWLAN). According to IEEE 802.11 IWLAN is accepted by the market and is used widely even in safety related applications up to SIL 3. WirelessHART is support by almost all international supplies and is now starting to gain greater acceptance within the process industry.

“Security is integrated in WirelessHART, IWLAN and wireless telecontrol equipment that is used in the cellular telephone network and is based on state-of-the art security technologies. The robustness and security of WirelessHART has been evaluated with good results in field tests, and IWLAN has been proved to work well in countless applications where there is a need for guaranteed deterministic communication with a guaranteed data bandwidth.“

Rogowski continues on the subject of security: “Wireless technology has improved dramatically over the past five to six years. Indeed, Honeywell is now on its third generation of industrial wireless solutions.

“However, cyber security will always be a concern in the world of open networks and it has become an essential requirement for process automation systems. This is not linked to wireless per se, but is a critical characteristic irrespective of the physical layer of the communication link.

“Minimizing maintenance costs, maximizing uptime and maximizing data throughput is another area of concern when considering battery powered wireless field devices. There will always be room for improvement in battery life and alternate methods of powering devices to achieve these goals and power management is a core CTQ to Honeywell customers.
“Honeywell’s OneWireless architecture and devices are structured to provide flexibility when balancing system requirements, speed, and data throughput and battery life. Our devices are designed for minimal power consumption to maximize life. We employ mesh powered backhaul and mesh powered field access points to further offload power budget burden from the devices to maximize life, update speed and data throughput.”

Karschnia agrees that wireless security is already very good. He said: “Emerson has is Smart Wireless technology has been tested by the US Federal Government to meet their requirements. It has also been tested by independent agencies and has been certified as meeting the latest state-of-the-art standards for security.” However he believes that there will always be more work to do in this area. “Security is a journey…not an event, and we are constantly working on this issue. However, most of Emerson customers would agree that we offer a very secure system.”

Why opt for wireless?
Asked about the benefit of wireless control solutions, Polzer believes that wireless communication makes an automation solution more flexible and transparent. He explained further: “Moving devices around is no longer a problem. With wireless technology investment and costs can be significantly reduced across the life of a plant. Of course, this means that the cost of cabling and installation is saved too and maintenance and critical systems, such as slip rings and data light barriers, are no longer required.”

However, he goes on to say that cost should not be the only consideration when specifying a wireless solution. “Data transmitted digitally is also of higher accuracy. Commissioning and installation and times for wireless system are also dramatically less than for a traditional wired solution.”

A further benefit, concludes Karschnia, is that of flexibility. “When designing a new petrochemical plant, for example, there will always be mistakes and changes required when production starts. Wireless gives you the ability to instantaneously get back on track, allowing for rapid adaptation to meet changing requirements.”

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