New sensor takes the heat

InTech, Jul 2004

INSPECTING A GAS TURBINE IN A power plant is necessary to check for wear and tear. Although the inspection is costly, a breakdown costs a company even more.

A new noncontact displacement sensor will help in condition monitoring.

Atlanta-based Radatec Inc., formed by two Georgia Tech researchers, created a sensor that will provide real-time information about critical mechanical components in areas previously off limits.

"Instead of having to shut down heavy equipment, Radatec's sensors allow operators to virtually see inside complex machinery and predict when repairs are needed," said Scott Billington, Radatec's president and co-founder.

Based on microwave technology, the sensors measure motion by sending a continuous microwave signal toward a vibrating or rotating object. This signal reflects back to a radio receiver in the sensor. A patented algorithm then compares the transmitted signal with the received one, calculating a measure of displacement.

In contrast to existing sensors that use capacitive, eddy current, or laser technologies these sensors:

* Operate at extremely high temperatures-up to 2,500°R

* Remain unaffected by contaminants such as oil, dust, and carbon deposits.

* Are immune to electromagnetic interference.

These characteristics allow the sensors to operate in harsh environments. "Existing sensors work well in certain applications, but can't be used in areas where it's very hot, dirty, or contaminated," said Jonathan Geisheimer, Radatec's cofounder and vice president. "And because these regions are often the most stressed areas of machinery, it's where major problems develop first."

Billington and Geisheimer launched Radatec in fall 2001, licensing technology they helped develop as researchers at Georgia Tech's Manufacturing Research Center and the Georgia Tech Research Institute. Since then, the company has filed several patents of its own, and in 2002 Radatec was admitted to ATDC, Georgia Tech's incubator for fast-growing technology companies.

The sensor platform works with 5.8-gigehertz components-parts found in consumer wireless networking applications, such as the high-speed routers in Starbucks stores.

The 5.8-gigahertz band also reduces weight, which has aerospace companies looking at the sensor.

"We've also reduced assembly costs 10 times by migrating to an electronic-circuit board product," said Dave Burgess, Radatec's director of business development.

The company is"telecom technology to machinery that fundamentally hasn't changed in a hundred years," Billington said. "Most of our suppliers are surprised why we want these parts because they were never intended for displacement sensing."

The company is streamlining its new prototype for production, shrinking size even further and working to improve signals. Other refinements include:

* Standard data bus. A communications system will allow Radatec's sensors to plug into other factory systems.

* Data recording. Radatec is adding logic that will trigger sensors to begin saving data when certain alarm levels trip, for example, if temperature or speed of machinery is too high.

* Self-calibration. Using an advanced radar vector tracking system, a "teaching" algorithm will increase accuracy by eliminating the effects of objects near the sensors.

During beta testing, one customer is monitoring a hydroelectric generator at a Georgia dam. Another partner is including the sensors in an online monitoring system for direct-current motors found on diesel-electric locomotives.