Infrared windows to the wiring

Sheila Kennedy says thermal imaging cameras can see energized electrical equipment without opening cabinets or doors.

By Sheila Kennedy, contributing editor

Thermal imaging applications and tools are growing in scope rapidly as opportunities for infrared (IR) technology are discovered. IR cameras have proven their worth for detecting heat where it’s unwanted. A complementary technology is the IR window, which gives the cameras a direct line of sight into energized electrical equipment without having to open cabinet doors or panels, thereby reducing the risk of electrical hazards to personnel and equipment and reducing inspection time.

The Mississippi National Guard (http://ms.ng.mil) is incorporating IR inspections in its building management strategy. “We’re in the infancy of thermography,” says Chuck Ballance, facility maintenance repair coordinator responsible for all of Mississippi’s National Guard facilities. “We’ve just issued a PO to buy our first camera, so we haven’t had any real ‘in field’ experience with it yet. That being said, we see the potential for energy management in the thermal envelopes of our structures, preventive maintenance, roof leak detection and electrical hot spots.”

Clear line of sight

IR windows must provide optimum visibility in addition to durability. The view through the ClirVu optic in Fluke’s (www.fluke.com) IR Windows is clear and unobstructed. ClirVu is a coating exclusive to Fluke IR Windows that seals the crystal optic before assembly. It provides protection from vibration and moisture degradation, and it withstands the extreme pressures and temperatures associated with an arc flash. Arc-tested, outdoor/indoor and low-voltage certified versions are available.

“The widespread acceptance of thermal imaging as a trusted maintenance practice has forced more emphasis on employee safety during routine IR scans,” says Rick Maday, Fluke Infrared Windows marketing manager. “The recently released 2012 edition of NFPA 70E outlines recommended procedures for performing IR scans, which, while necessary, can be time consuming to adhere to. IR Windows make NFPA 70E-compliant IR scans safer, faster and easier.”

Efficiency and safety

IR windows must provide optimum visibility in addition to durability.

Installing an IR window without screws eliminates stripping and corrosion problems. Flir’s (www.flir.com) IRW Series infrared inspection windows use a PIRma-Lock system to simplify installation and provide more durability over time. Just one hole is required for installation. The teeth of an electrical locknut tightly fasten the window to the inside of the panel cover and automatically ground it. The windows themselves have a broadband crystal lens that lets laser pointers and camera lighting through for improved inspections, diagnostics and documentation.

“IR windows are great tools to include in a condition monitoring program,” says Russell Bushee, thermography instructor at the Flir Systems Infrared Training Center. “They keep the thermographer from having to remove panels, so they’re not exposed to the full energy potential within the system. This means that they can wear lower-calorie arc-flash clothing than the full rated value, but they still need to wear some protection – mainly the arc flash face shield.”

Polymer alternative

An alternative to crystal IR windows is polymer. IRISS’s (www.iriss.com) polymer-based, industrial-grade windows use specially engineered grills to reinforce the lens, providing resistance to impacts and sustained loads. The polymer used in the lens is malleable and versatile, and it has a fixed and stable transmission (FAST) rate that’s been tested in extreme environments for two decades with no degradation in usability or thermal acuity. In contrast, traditional crystal windows tend to be more fragile and subject to a degrading transmission rate.

“Making infrared thermography affordable and safe requires more than just an off-the-shelf approach,” says Rob Miller, IRISS senior technical advisor. “As technology has advanced, so also has the understanding of the dangers of human interaction with electrical systems. IRISS products are designed by industrial thermographers to facilitate safe inspections while limiting the interaction between personnel and the environment within the enclosure.”

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Exiscan (www.exiscan.com) also uses a polymer optic in its line of IR windows for durability and accuracy. The patent-pending design requires no grills and the window housings are made primarily of aluminum and steel to enhance structural integrity. The square window shape yields a significant increase in viewing area compared to conventional round configurations.

“Currently, there are two options for companies that need to perform these inspections,” says Tim Rohrer, Exiscan president and founder. “A single engineer can use the IR windows and eliminate inspection-related risks; or they can send two or three engineers wearing protective gear to open each piece of equipment, thereby dramatically elevating the risk level.”

Email Contributing Editor Sheila Kennedy, managing director of Additive Communications, at sheila@addcomm.com.

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