MACHINE SAFETY FEATURE
THERMAL IMAGING: Safe inspection of working systems
O
ne of the great benefits of thermal imaging is that it permits the
detection of a variety of potential faults, without the need to interrupt production to find them. With the use of the appropriate infrared camera for the application, and possibly, an IR inspection window, this can be achieved without personal risk to the operator. This non-contact technology allows the
safe temperature profiling of moving targets, high voltage, and hot and volatile objects, a facility that no other predictive maintenance tool can provide. Detecting electrical faults is naturally one of the principal application areas for thermal imaging, especially as inspections can be conducted when systems are under load. Any resistance to electrical current can
cause an increase in temperature. This can then cause components to fail, potentially resulting in unplanned outages and even personal injury. If left unchecked, rising heat will ultimately melt connections and break the circuit which can result in fire. Even a small electrical problem can
result in devastating consequences in terms of the destruction of goods and can lead to production downtime, water damage and the risk to human life. In addition to loose connections, electrical systems suffer from load imbalances, corrosion and increased impedance to the current. Thermography can quickly locate these hotspots, determine the severity and help establish a time frame in which the equipment should be repaired. Although thermal imaging is the perfect predictive maintenance method for these applications, several factors do need to be considered to eliminate any health and safety risk and to ensure the correct interpretation of thermal imaging results. Dave Blain, managing director of Thermascan, a company that undertakes surveys, hires out and sells FLIR infrared cameras and trains would-be thermographers. Selecting the most suitable camera for the job is critical and its down to what the user wants to do with infrared. The introduction of the compact, torch-style infrared camera has seen the market expand significantly. “These are great toolbox instruments,”
Blain explains. “They are ideal troubleshooting and checking tools, for doing a quick scan for hotspots and for proving that you have repaired the electrical fault correctly. “However, if you need a camera that
provides the necessary information for you to diagnose a broad range of electrical and mechanical faults, you need to move up the range.” Blain’s advice is to try before you buy, or hire different camera models to try them out in the field. There are two key factors when
considering an infrared model for detecting faults; clarity of image and operational safety. Blain adds: “Both are best served by a camera with a minimum 320 x 240 pixel array. This gives an adequate number of measurement points on an image to provide a typical sensitivity value of 50-80mK.” To stand a chance of diagnosing a fault
with a less sensitive camera means you have to stand closer to the subject. “And this is where safety can be compromised. An electrician needs a clear image at a good safe distance,” says Blain. He continues: “To use infrared to
discover a range of problems you need the flexibility of at least a mid-range camera, a FLIR T-Series would be the level I would recommend. Quite simply, there is no point in buying a low-price, low resolution troubleshooting camera that can only give you a clear image for fault diagnosis when it’s six inches away from the target.” These higher specification cameras also have a range of standard features to
FLIR T-Series cameras are flexible, making them easy to aim, focus, and use in electrical and mechanical inspection
make it even easier to apply infrared. For example, they include a high quality digital camera and the ability to overlay digital and thermal images to emphasise any temperature abnormality. Interchangeable optics are also highly valuable as they allow the camera to be best adapted to the task, as does a tiltable screen for applications such as examining the health of busbars in a chamber, for example. Wireless technology is another boon,
particularly in hard-to-access areas. Images, complete with their radiometric data and other information, such as a GPS reference, can be transmitted from the thermal imaging camera to smart phones and tablet computers. In this way users can share critical information immediately with decision makers on- site or via email. Although needing to be treated with respect, thermal imaging brings many health and safety benefits to the workplace. However, as Blain summarises: “Just make sure the scope of your thermal imaging camera matches the scope of your job and invest in some dedicated training. That way infrared will add value to the service you provide and keep you safe in the process.”
FLIR Systems T: 01732 220011
www.flir.com
ELECTRICAL ENGINEERING | DECEMBER/JANUARY 2017 23
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