Eye on the ball

Microwave technology is helping machine operators solve problems before they occur by allowing them to monitor in real time the condition of parts that traditional sensors can’t reach.

Condition monitoring – the ability to acquire real-time information about a machine’s performance and solve problems even before they occur – is an industrial tool that is growing in importance.

But while this handy technique is already preventing downtime in a variety of applications, its effectiveness is limited because traditional sensor technology doesn’t always behave well in extreme conditions, often making it impossible to monitor the most critical areas of a machine.

Enter Atlanta-based Radatec, a Georgia tech spin-off that could transform the world of condition monitoring with a newly-developed non-contact displacement sensor.

Scheduled for commercial release later this summer, Radatec’s sensors measure motion by sending a continuous microwave signal towards a vibrating or rotating object. This signal is reflected back to a radio receiver in the sensor, where a patented algorithm compares the transmitted signal with the received one, calculating a measure of displacement.

Radatec’s business development manager Dave Burgess said the technology could be used to provide real-time information about critical mechanical components in areas that were previously off limits. This will cut out the need to shut down heavy equipment and instead allow operators to ‘virtually’ view the complex machinery inside.

Burgess explained that the capacitive, eddy current or laser-based sensors typically used in condition monitoring applications can’t be used in areas that are hot, dirty or contaminated. Unsurprisingly, these are the very areas that are subjected to the greatest amount of stress and arguably most in need of condition monitoring.

For instance, lasers, which require a spotless environment to be effective, are rendered inoperable by the presence of carbon deposits, while eddy current sensors – which work by sensing changes in a magnetic field – become inaccurate at high temperatures.

In contrast, he said that Radatec’s sensors operate at temperatures of up to 2,500 degrees F, are unaffected by contaminants such as oil, dust and carbon deposits and are blissfully immune to electromagnetic interference.

One example of an area where the sensors have opened up uncharted waters is in the condition monitoring of gas turbines used in aircraft and power generation applications. Burgess explained that operators typically base the decision on when to replace parts on the expected lifetime of components rather than the kind of dynamic analysis made possible by the new sensors.

Radatec’s sensors were initially developed for military aircraft, and while information regarding this application is restricted by the government, Burgess did reveal that a system which runs in the 24.1Ghz band is undergoing tests in military aircraft gas turbines.

The industrial version of the sensor, has been developed largely because of a need to generate revenues now. It is essentially a scaled-down version of the high-end military technology. This system runs at 5.8Ghz and is smaller, lighter and cheaper than its military forbear, Burgess said.

Testing with industrial partners began earlier this year. One customer is using the technology to monitor a hydroelectric generator at a Georgia dam, while another is trying it in a monitoring system in high-speed diesel-electric locomotive engines.

Burgess explained that problems occur when the commutator in the electric motor begins to wear.

Deterioration in the outer roundness of this component can cause arcing and eventually lead to the motor breaking.

By using the sensors to monitor the roundness of the motor in real time, Burgess said that train operators will be able to change the motor round in the depot just before it breaks rather than run the risk of it breaking down in service. He added that while the current tests involve freight trains, the technology could also be applied to high-speed commuter trains.

While unwilling to name either the turbine OEM or the train operator, Burgess said that the company will be making an announcement about its customers next month.

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