Energy Harvesting Powers Wireless Sensor Networks In Industrial Apps

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Factory and plant process automation are being re-invented thanks to advances in wireless sensor communications for industrial applications. These innovations are empowering automation engineers to blend old manufacturing knowhow with the new capabilities of modern wireless communications.

For many industrial applications, wireless sensor networks often cost much less than wired solutions, both in the short and long terms, due to affiliated troubleshooting, maintenance, and repair issues. That’s because it’s much easier to track down a defect or a fault in wireless sensor networks than a wired factory floor laden with miles and miles of often buried wiring. Wireless also is more flexible, allowing easier and quicker reconfiguration of a network to meet constantly changing plant needs for adjusting to newer product types and models.

Wireless sensor networks also can stream video via 3G and 4G network communications technologies and their faster data transfers, which is very valuable in critical industrial sites that require around the clock monitoring and surveillance. Gas pipelines, video security systems, power facilities, water systems, and many other vital installations require immediate response to failures, tampering incidents, and accidents, and wireless sensor networks can save a company millions of dollars in fines for environmental violations, not to mention immediate control of environmental damages.

There’s one caveat to using wireless communications networking in an industrial setting, though. The wide-scale availability of human-machine interface devices like smart phones and tablets poses potential security risks to wireless industrial automation if the correct security methods aren’t employed (see “How Safe is Wireless Sensor Networking?”). Fortunately, many modern wireless sensor networking topologies and protocols feature built-in tools to minimize vulnerabilities.

The Power Advantage

The benefits of wireless sensor networks go well beyond these advantages. For example, wireless sensing and networking enables manufacturers to use low-power electronics, saving energy. Manufacturers can focus on the lowest possible power consumption, thanks to advances in communications protocols and the sensors and transceivers that power them.

Energy harvesting techniques save even more energy by working with modern IC functions. Some sensors, microcontrollers, power-management devices, and transceivers can operate from energy produced by a few degrees of heat, a small amount of mechanical motion, or some indoor lighting, all energy sources available within industrial plants (Fig. 1).

5. Linear Technology supplies a wide range of ultra-low-power modules targeted for energy harvesting applications from piezoelectric and photovoltaic sources as well as thermoelectric generators (TEGs). They include the LTC3588-1/2 piezoelectric energy power supply (a), the LTC3108/9 TEG (b), and the LTC3105 solar energy 400-mA step-up dc-dc converter (c). (courtesy of Linear Technology Corp.)

The Dust Networks Eterna transceiver chips implement IEEE 802.15.4e, which came out this year. Together with systems-on-chips (SoCs), this second-generation product features power dissipation levels 50% less than the earlier-generation they replace, cementing the company’s lead in industrial wireless sensor networking (Fig. 6). Dust Networks claims that products based on its Eterna technology consume and eighth of the power of competitive offerings, which means they can last eight times longer and can be eight times “greener” even if they’re line-powered.

7. This self-contained SureCros Q45 photoelectric-sensor transceiver from Banner Engineering satisfies industrial low-power wireless sensor network applications. Its power-management circuit delivers an extended battery lifetime up to five years for two AA lithium batteries (courtesy of Banner Engineering Inc.)

How Safe Is Wireless Sensor Networking?

Advanced human-machine interface (HMI) devices like smart phones and tablets may make industrial wireless networking control easier and simpler. But there are risks involved in cyber attacks, some intentional and many unintentional, that can render a plant’s operation all but dead unless sufficient safeguards are taken.

From February through April of this year, personnel from cyber security firm Cyberti Corp. covered nearly 4000 miles of roads hunting for IEEE802.11 a/b/g/n wireless transmissions, specifically looking for the organizationally unique identifiers (OUIs) of power control system providers. These OUIs are applied by the network device provider, the vendor of the control system hardware.

Cyeberti’s study showed that OUIs and the full media-access control (MAC) address often are left unprotected even in the most secure security settings. Cyberti cofounder and chief security officer Matthew E. Luallen warns that control system protocols like Modbus, EtherNet/IP, PCCC, DNP3, and ICCP are natively unauthenticated, leaving hackers free to do whatever they want, should the data associates control system MAC addresses on an unprotected or poorly protected wireless network.

Luallen adds that portable devices may serve as the entry point to the protected control infrastructure using cached remote access credentials and applications stored on them. Wireless devices may also be configured to multihome between IEEE 802.11 wireless networks and cellular networks, creating an unwanted Internet gateway.

“Portable electronic devices must not be categorized as tools like a hammer or wrench. These devices retain information about the control system environment and can cause additional harm if placed in untrustworthy hands. Whether the device is a traditional laptop, iPhone, iPad, or HART communicator, the tool may contain communication points, tags, configuration settings, logic, diagrams, blueprints, and specifics about the environment that a skilled attacker can leverage,” Luallen says.

“First and foremost, one must investigate the true productivity gains and reduced costs of using mobile applications that have unfettered access to a control system,” he adds. Luallen also says that control system remote access should not be allowed from traditional consumer phones or tablets. “If you have a realistic fear of the cyber risks that exist, you should think long and hard before doing anything that increases your attack surface as much as adding mobile applications can. The risk may well prove to be greater than the actual productivity gained.”

Sensors Put Intelligence in the Smart Grid

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