Full Redundancy Makes Smart Wireless Smarter

Emerson Explains How the Company's New Smart Wireless Platform Facilitates the Implementation of Critical Control Applications

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Emerson Exchange 2009

Emerson announced a unique approach to redundancy for Smart Wireless monitoring and control solutions at the Emerson Global Users Exchange this week in Orlando, Fla.

"Emerson Smart Wireless has been adopted at thousands of customer sites globally," said Bob Karschnia, Emerson vice president, wireless. "Using wireless is a big step. Now available with the DeltaV S-series digital automation system, full redundancy protects the wireless network from any single point of failure by allowing primary failover to ensure that data always is delivered even if there is a malfunction."

The enhancements include redundant wireless I/O, power and communications and a redundant Smart Wireless Remote Link. The Remote Link connects the wireless field network to a DeltaV system, which makes an optimized PID available for wireless control. The new full redundancy furthers the strength of Smart Wireless technology as a complement to wired and bus approaches on capital projects.

"As plant studies have shown, reliable robust wireless technology should be a key component of all capital projects," said Karschnia. "Plants using wireless realize savings and become smarter through simpler engineering and construction, flexible startup, faster deployment and project completion, and changing automation needs. Today wireless is readily deployed for monitoring, and customers have asked for redundancy for control as well as for critical monitoring points."

Customers need proof that control with wireless is viable, added Karschnia. "We've responded with real-world Smart Wireless installations using one-second updates, enhanced PID, battery management and WirelessHART," he said.

The new wireless network redundancy and robustness provide confidence to customers to now extend use to critical monitoring and control applications with the same flexibility and ease of use of the entire Smart Wireless platform.

Smart Wireless is based on the WirelessHART standard, which is designed for control and monitoring applications and delivers 99.9% reliability because of the self-organizing nature of the network, ensuring data is delivered reliably. This level of reliability is a prerequisite to using wireless technology for any critical monitoring or control application. Devices that conform to the WirelessHART specification can sense measurements at update rates up to once per second. WirelessHART also allows exception reporting for network efficiency—devices only communicate a measurement value if it has changed significantly since the last communication, or if the time since the last communication has exceeded a required reporting time, optimizing battery life.

Two recent installations demonstrated the effectiveness of Smart Wireless for control over WirelessHART networks. At bioprocess technologies supplier Broadley James, WirelessHART pH and temperature transmitters control a single-use disposable bioreactor. "We conducted batch runs using mammalian cell culture," said Scott Broadley, president of Broadley James. "The observed pH and temperature control using wireless measurements was equivalent to that achieved using wired transmitters." 

Similar results were seen at another installation at University of Texas where stripper and absorber control is done using WirelessHART transmitters. Column pressure control and heater stream flow control using WirelessHART transmitters provided the same dynamic response and comparable performance to that achieved using wired transmitters.

Both installations use an enhanced PID algorithm available with the DeltaV S-series. This PID algorithm for wireless devices delivers high accuracy control in an exception- reporting environment.

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