(This is Part 4 of a series by Ray Garvey on “Changing the way we do thermography.” The previous article are available at www.reliableplant.com.)

Vibration analysis and thermography are both commonly used walk-around data collection systems used for proactive and predictive maintenance in industrial plants. Historically, these two technologies have been separate and distinct. Vibration analysis has been performed using vibration analyzers, while thermography has been accomplished using infrared imaging camera systems. What if the two technologies could come together in a single platform? What if other dynamic signal analysis techniques like ultrasonics, magnetic flux or electrical current analysis could also be done? What if other imaging analysis techniques like borescope inspection and other two-dimensional or three-dimensional imaging techniques could be integrated with the dynamic measurements? This article invites readers to respond after considering this new world of possibilities .

Infrared imagers are commonly used for thermographic inspections of equipment. State of the art for infrared inspection process involves the use of an uncooled, radiometric, focal plane array, infrared camera plus visible camera built into a lightweight, handheld package with onboard digital memory, an LCD display and interactive user interface. Visible light imaging systems are also used for inspection of equipment. Examples of such applications are borescopes, fiberscopes and even conventional video cameras.

Various dynamic measurement systems have also been developed to monitor the operational health of equipment. Examples of such systems are vibration analysis devices, sonic or ultrasonic measurement devices, and electromagnetic spectrum analyzers.

Emerson Process Management’s Machinery Health Management business has experience designing, building and selling image analysis systems used by thermographers, and also has experience with designing, building and selling dynamic signal analyzers used by vibration analysts. Even though both product lines were out of one company, no one has ever considered putting them together into a single handheld system. They were individual products for use by different people and built from very different technology bases.

In January 2006, four engineers proposed integration of these technologies into a single platform. We described practical ways to do either of these things: 1) integrate the functionality of imaging and image analysis into a handheld vibration platform, or 2) integrate the functionality of a dynamic signal analyzer into a handheld imaging system. See our U.S. Patent Application, “Automation of imaging and dynamic signal analyses.”

The engineers say it is feasible to integrate different kinds of dynamic indications measuring machinery health and imagery indications that separately measure machinery health into a single handheld platform. OK, it is practical, but who needs it to be integrated? Traditionally, image analysis and dynamic signal analysis have been performed using different technicians holding separate boxes. Is this going to change? One manager commented that putting these two things together is like building a Swiss Army knife. Most people prefer to buy dedicated, separate devices.

Does it make sense to combine dynamic signal and image-type analysis in a single machinery health platform? On the one hand, you can save a lot of money by building in the shared functionality of a single handheld device. Also, the onboard software tools now make it much more practical for one person to capture the skill needed to perform both thermography and vibration analysis. In fact, many people are certified to use both. Many of the mechanical and electrical systems are best surveyed using both technologies.

Dynamic sensors typically employ devices such as accelerometers, piezoelectric components, electrical current or voltage probes, thermocouples, Pitot tubes, and sonic or ultrasonic detectors. Dynamic analysis or dynamic signal analysis techniques include Fast Fourier Transform (FFT) vibration analysis, waveform vibration analysis, spectral vibration analysis, stress wave analysis, transient analysis, sonic analysis, ultrasonic analysis, FFT flux analysis and FFT current analysis. Such analysis generally produces one or more dynamic indications of machine health.

Functions historically performed on the display of an infrared camera include these: live thermal image, live visual image, frozen visual image, frozen thermal image, text annotation, graphic annotation, temperature at cursor points, temperature histogram, temperature profile, alarms, parameters, user instructions, etc.

How often does it make sense to use both technologies together? Table 1 presents a matrix of different combinations of sensors that may beneficially be employed to measure the health of particular components in an electrical switchyard. Matrix elements labeled “No” indicate that the sensor in that column is generally not applicable for inspecting the component in that row. However, under special circumstances such use may be appropriate.

Table 1. Inspection of switchgear with an integrated system.

Component

Sensor Applicability

IR

Visible

Ultrasonic

Vibration

Power line

Yes

Yes

Yes

No

Connection

Yes

Yes

Yes

No

Insulator

Yes

Yes

Yes

No

Bushing

Yes

Yes

Yes

No

Junction

Yes

Yes

Yes

No

Coupling

Yes

Yes

Yes

No

Disconnect

Yes

Yes

Yes

No

Current transformer

Yes

Yes

Yes

No

Disconnect

Yes

Yes

Yes

No

Main transformer

Yes

Yes

Yes

No

Load tap changer

Yes

No

Yes

No

Breaker

Yes

Yes

Yes

No

Operating status

Yes

Yes

No

No

Cooling system

Yes

Yes

No

No

Motor

Yes

Yes

No

Yes

Pump

Yes

Yes

No

Yes

Gas compressor

Yes

Yes

Yes

Yes

When does it make sense to combine dynamic signal analysis and image indications of machinery health into a single device? We invite your feedback. Please e-mail your responses to ray.garvey@emersonprocess.com.