Figure 1 -- Condition monitoring: Magnetically mounted sensor (left) measures vibration and draws power from module that harvests energy from vibration (right). Source: GE Energy.
Security raises concerns. “The fear of an unauthorized person gaining access into the company’s internal control network — that’s the biggest thing,” notes Scott Brady, director of marketing for SKF Condition Monitoring, San Diego. This fear is overblown, he says — “there are technologies that can prevent that...”
Nonetheless, he acknowledges, “there is reason to be concerned [about security].”
Unfamiliarity with infrastructure requirements is another obstacle, notes Ed Bondoc, SKF’s wireless product manager. “Many end-users don’t realize that you actually need a wireless umbrella over the area, one installed at the plant, to use wireless.”
Yet another reason that plants historically have resisted wireless is a concern about reliability. “It’s not a well-founded concern, and may have been related to past experience,” says Bondoc. Citing WiFi as an example, he believes resistance “came from high expectations from vendors that said wireless could do more than the systems could deliver.”
Wireless data transmission certainly promises to deliver numerous benefits to plants. Bart Winters, HPS solutions manager for safety and reliability, points to improvements in plant reliability, operational efficiency and worker safety. To these, Karschnia adds achieving better environmental performance. “Everything we’re doing is about one of these things.”
Implementation ranges from installing units (drawing power either from the plant electrical network or from batteries, etc.) at a specific location to carrying around handheld devices. Interest is high in both the fixed and portable approaches, notes Bondoc.
Wireless will change offline monitoring of data, says Becker. “A worker walks around the plant and tries to assess the relative health of an asset. Wireless is allowing inexpensive gathering of information on a much greater percentage of equipment.” This more frequent and broader assessment will help identify problems and solutions before secondary damage occurs, he notes. And that’ll lead to more uptime, as well as improved productivity by permitting staff to better monitor critical assets.
Brady suggests the future of handhelds “depends on connecting to the wireless network.” That’s because “some guy out there [in the plant] with an industrial PDA [personal digital assistant] will want to tap into the whole control system. ‘What’s the system doing now?,’ he might ask, if he hears a noise. He might need instructions. He might need to contact someone to get repair done.” In short, the field operator will want live access to plant control and communications systems.
However, for continual monitoring of conditions such as vibration nothing beats a fixed device, says Winters. “It’s available all the time and at lower cost.”
The interest in condition monitoring will spur the range of applications supported by wireless instrument networks to expand beyond the traditional realm of 4–20 mA, predicts Johnston.
For instance, many plants currently only take advantage of the 4–20-mA output of HART-enabled devices, leaving valuable diagnostic data stranded at the device. Wireless adapters can provide a way to retrieve such information. Already many vendors offer a variety of wireless transmitters. And the roster is bound to significantly grow.
Becker foresees wireless networks of greater scope, including use of different types of instruments — with a focus on answering three general questions he believes apply to all process operations: How can worker safety be enhanced? How can worker mobility in the plant be improved? How can islands of automation be connected?