Plant & Works Engineering

Infrared - value for money technology

Published:  12 November, 2014

Thermal imaging has never been better value for money. The industry saw a significant fall in the cost of the technology five or more years ago but while prices have continued to be revised downwards, what you get for your money has significantly increased. Features that were once only seen in high-end cameras are now common at virtually every level. PWE reports.

The combination of visual and thermal imaging on the same unit is a typical example. Latest generation models are also able to discern even smaller temperature differences and this is so important for achieving an accurate diagnosis of the problem.

Image format improvements have also been made. Cameras are now taking images as full radiometric jpgs. This means all temperature data is included in the images and they can be easily incorporated into a standard Word document for report generation. Analysis tools have become much more sophisticated too. Options include area minimum and maximum, colour alarms and fusion tools.

FLIR Systems has taken the fusion capability even further with its patented MSX technology. This captures detail from the visual image to sharpen the image of its thermal counterpart making it possible, for example, to see the thermal profile of a fuse box and any writing on the housing it as well. Target identification is therefore much easier with this technology .

Need to know

Developers of the technology remain focused on improving user interfaces, building-in smart features to make thermal imaging increasingly easy to apply across a range of tasks. However, none of these innovations can replace the fundamental need for the user to have a good foundation in electrical engineering, which Dave Blain, managing director of Thermascan, a company that undertakes thermal surveys and trains would-be thermographers, says is vital in order to conduct a meaningful thermal imaging survey. He explains that without this essential knowledge, it’s impossible to determine if the thermal values on the image indicate normal operating temperatures of a potential fault.

The problem needs to be put into context as not everything showing hot is a fault. For example, is there high current or high resistance contact where a high operating temperature may be the norm? And it is also vital that the camera user has a thorough grounding in infrared, so basic training is an absolute must for anyone planning to incorporate thermal imaging into their daily routine.

Reflections from cabinets and background lighting can completely skew the results . A cabinet may be glowing hot in the thermal image but that could simply be caused by heat from overhead lighting or indeed the body-heat of the camera operator. Busbars and DIN rail connectors can often cause problems, as can different surface coatings.

It’s all to do with emissivity, the term that describes the ratio of emissive power of a surface at a given temperature to that of a black body at the same temperature and with the same surroundings. In most cases the thermal readings need to be adjusted to take this emissivity into account.

Right model

Selecting the most suitable camera for the task is also critical and that’s down to what you want to do with infrared.

“The low-end trouble shooting cameras are great toolbox instruments ”, explains Blain. “They are a good choice for doing a quick scan for hotspots and for proving you have repaired the fault correctly.”

He advises, however, that if you need a camera that provides the necessary information for the effective diagnosis of a broad range of electrical faults, you should move up the range. And there are two key factors to be considered when choosing the best model, clarity of image and operational safety.

“Both are best served by a camera with a minimum 320 x 240 pixel resolution. This gives you 76,800 measurement points and allows the electrician to obtain a clear image at a safe distance. Quite simply, there is no point in buying a low-price, low resolution camera that can only give you a clear image for fault diagnosis when it’s six inches away from the target.”

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 certainly add value to the service you provide and keep you safe in the process.”

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