Thermal Imaging Devices
Published: January 2011
In the electrical industry, thermal imaging devices, also called infrared cameras, play an increasingly important role as a powerful diagnostic tool. They are used to quickly scan electrical system connections, fuses, junction boxes, switchgear and other components to immediately identify potential problems.
By reading and displaying images in the infrared spectrum that identify temperature differences, thermal scans have become indispensable for avoiding problems in critical information communication technology infrastructure. As energy-savings initiatives receive growing attention, thermal cameras are routinely used for making energy audits of buildings.
Thermal imaging technology is used in a broad range of industries and a host of manufacturers offer many types of specialized devices. The best-known names in the electrical market are Flir and Fluke. Ideal Industries (www.idealindustries.com) and Extech (www.extech.com) (now a Flir company), have added thermal imagers to their product lines. Testo Inc. (www.testo.com/thermal), also makes a line of these tools.
Thermal imaging technology is not new to the electrical market, but products available today have changed from those available only two or three years ago.
“Today’s infrared cameras are all about ‘more’: more compact, more powerful, more rugged, more connected, and more affordable than ever before. They also are simpler to use,” said Andre Rebelo, global communications manager at Flir Systems (www.flir.com).
Michael Stuart, senior marketing product manager at Fluke Corp. (www.fluke.com/thermography), said thermal imaging is being used by both greater numbers of people and a much broader range of people.
“This technology is very appealing because it’s cool,” Stuart said. “It’s intellectually stimulating, and it’s immediately applicable. There is an amazing range of applications for which heat is an indicator. Now there is no price or technology barrier to entry. People are finding all kinds of ‘off-book’ applications.”
Basic thermal imaging applications
Flir, Andre Rebelo: “An infrared camera composes thousands of pixels of temperature readings into a revealing image, literally providing the electrical contractor with a ‘big picture’ of the condition of electrical systems and components. In general, electrical workers use infrared cameras both as a key tool for predictive maintenance as well as real-time diagnostics and repairs.
“An infrared camera is a first-order diagnostic tool: it can be used to scan a job site to quickly zero in on areas where hot or cold spots could mean trouble. Then, an electrical contractor can use a multimeter, clamp meter, power quality analyzer, or other test equipment to collect more granular diagnostic readings.
“Specific examples of what thermal imaging infrared cameras can detect include overheating electrical connections that are loose, stressed, corroded or overloaded. Unbalanced loads, overloaded motor controls and load centers all reveal themselves with increased temperatures. A variety of motor-related issues can also appear under the watchful eye of an infrared camera including overheated commutators or shorted windings. In the power distribution system, the potential for overheating, damage and failure arises at circuit breakers, capacitors, disconnects and protective devices, such as lightning arrestors.
“Examining transformers with an infrared camera might reveal issues related to ineffective cooling systems. Tubes might be restricted or blocked, fluid level might be low, or connections might be damaged or deteriorated.
“As an essential technology for predictive maintenance of electrical systems, temperature might provide telltale clues to a component’s inefficient operation long before a failure were to occur. By addressing such issues predictively, a customer can save thousands of dollars on wasted energy that, generally speaking, would have otherwise been converted to heat and eventually have led to failure,” Rebelo said.
Fluke, Michael Stuart: “Electricians scan operational system components looking for unusual temperatures that might indicate a problem in development. Most components of electrical, electro-mechanical and mechanical systems begin to overheat when their operating conditions slip out of spec. For electrical components, the cause can be anything from unbalanced phases to loose connectors. For mechanical systems, the cause is frequently misalignment or lubrication.
“When troubleshooting, an electrician is usually trying to identify the cause of operational issues. A thermal imager allows him to scan all of the electrical and moving parts while they are operational, without contacting them directly, increasing his safety. This enables him to quickly either rule out or pinpoint common culprits. After he makes a repair, another scan of the operational system verifies the heat-symptom has been alleviated.
“During routine maintenance, an electrician will begin with a thermal scan, both to identify component issues that might not show up on other types of checks as well as to get a general indication of unit health. Most departments keep thermal images of all important system components on file as a baseline for comparison when issues arise.
“During energy inspections, an electrician will use the thermal imager to help evaluate the operational efficiency of large loads. Overheating components are often a sign that a unit is consuming more energy than it should,” Stuart said.
Advances in technology
Flir, Andre Rebelo: “Today’s infrared cameras continue to deliver the innovation and robust capabilities of high-end professional-grade thermal imagers in more compact and more affordable point-and-shoot models that perform like the heavyweights. Resolution continues to climb to the level of 320-by-240 pixels, which some in the industry qualify as ‘high-definition’ infrared.
“Compared to two years ago, thermal imaging is getting more attention from the electrical industry because it is becoming a more mature technology, and it has become more accessible due to lower pricing. Two years ago, the entry point for an electrician-grade infrared camera was $3,000. We’re about to see an electrician-worthy $1,200 model be introduced. Mid-range infrared cameras hovered around $10,000. We’re on the verge of seeing radically advanced infrared cameras available for less than that price point.
“One substantial way in which electrical thermographers take the usefulness and value of their infrared images to the next level is by inserting them in reports that can be prepared for clients for more in-depth explanations of what was found. Instant reports is a new capability built into the camera. An electrical worker is able to prepare reports on the spot, without a PC, cables or any other hardware. Images and annotations are selected right on the camera screen and inserted into a report template.
“Finally, the increased visibility and prominence of energy efficiency has made infrared cameras indispensable for home/building energy audits to track heating and cooling loss, but also, electrical systems are being scrutinized for optimized operation,” Rebelo said.
Fluke, Michael Stuart: “The trend is to [add] more accuracy and ease-of-use features in lower priced models. However, it is probably not fair to say that thermal imaging accuracy overall has increased substantially. High-accuracy models cost upwards of $15,000 and are not the market focus, so less R&D is devoted to increasing the highest possible accuracy.
“Broadening the user base out from specialists to a huge range of electricians and technicians brought a far wider span of user scenarios and usage requirements into the R&D process. Making a tool usable and user-friendly to this new audience requires everything from drop testing at 6 feet and higher, to highly intuitive menus to saving in more image formats, to ever-increasing options in the accompanying PC software. For example, users can now use telephoto and wide-angle lenses with their thermal imager, greatly improving the quality of what they see in their field of view, whether from a distance or wide angle in a tight space,” Stuart said.
An infrared camera in every tool bag?
Once considered a specialist’s instrument, a growing number of electricians are carrying thermal imagers, according to both Rebelo and Stuart.
“Historically, infrared cameras were very expensive and were often considered the domain of thermographers or consultants who specialized in diagnostics based on thermal imaging,” said Rebelo. “With today’s downward-pricing progress, along with added diagnostic tools built into the camera and easier-to-use point-and-shoot models, all are making infrared accessible to more and more electricians everywhere.”
Stuart said it is now very common for an electrician’s team to have at least one thermal imager.
“That goes for both electrical contractors as well as staff electrician,” he said. “Depending on the size of the team, they may have more than one, and they may either share it among themselves or make one person the dedicated thermographer. There are several reasons for this. One, the price has come down drastically in the past five to seven years, making thermal imagers easily affordable. Two, the units are far more rugged than they used to be, so they can be incorporated into daily work without concern. Three, ease of use has been substantially improved.
“Basic training is still a good idea, so that the user understands how to interpret the thermal data he sees and is not misled by reflective surfaces. But, by and large, for most common applications, specialized training is not required,” Stuart said.
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at email@example.com.