Thermal imaging is increasingly becoming a significant diagnostic procedure in many industries in this day and age. Insurance companies have made it mandatory for the sake of fire protection whereas most electrical contractors are being requested to conduct thermal surveys as a vital component of their fixed wiring inspections.
Typically, conducting thermal imaging surveys entails buying an appropriate camera, pointing towards a given target and finally shooting. You then have to rely on software editing to do the rest of the work. Sounds simple, does it? Is it possible for a camera to lie? Just how serious can the misinterpretations of thermal imaging be?
For a start, it is necessary to comprehend a little bit about thermography and the roles of a thermal camera. It has a lens which allows in infra-red radiation to pass through an infra-red detector. The camera’s software translates the radiation into a visible image which is viewable on-screen and analyzable by the user.
It encompasses the use of the camera alongside the analysis of the thermal patterns with the aim of drawing some conclusions concerning the problems at hand.
The inexperienced eye is easily drawn to the hotter portions of the thermal image and immediately takes it for granted that a problem exists. This, however, is not always the case. A number of factors have to be considered when analyzing the thermal image and the many issues that might give rise to errors. The case study that follows will take into consideration the two most common problems which are made while utilizing the thermal cameras for the purpose of electrical inspections.
Misinterpretations of Reflections
With the visible light, you notice reflections always. Mirrors, glasses and the polished surfaces all reflect some light to their surrounding environments. By the same token, reflections of heat are also normally in existence in the infra-red spectrum.
Whenever a thermal camera is directed at a polished surface like Copper, Aluminum, and Steel, only a tiny chunk of what the camera observes is radiated from the actual surface of the metal itself. The vast majority of the reflection actually emanates from the other objects which impact the target.
Given the high number of times you might encounter the metal contacts in a typical electrical environment, there is plenty of room for errors to arise while diagnosing faults. The failure to comprehend this will often result in potentially dangerous issues being missed out on and worse still, being likely signed off safe in an evacuation report.
Reflected Apparent Temperature and Emissivity
Thermal cameras do contain a number of settings which are adjustable. To arrive at the most accurate temperature measurements possible, the right settings have to be applied. You may probably ask why temperature readings are necessary. After all, surely you can even spot the problem by just looking for the hotter portions on the image.
It is necessary to, first of all, understand that the image will often appear the same irrespective of the kinds of settings utilized. Secondly, as pertains to electrical applications, the use of temperature readings is by all means vital. This information will let you classify the seriousness of the faults and make recommendations for timely appropriate maintenance.
Some of the camera’s settings will have only a small impact on the temperature values. However, the two which will normally the most significant impacts are the emissivity and the reflected apparent temperatures.
Emissivity refers to the object’s capacity to exude some radiation. Objects that have low emissivity are unsuitable for infra-red thermography because they reflect more and make the task of deriving true temperature readings more difficult and in some cases impossible.
The reflected apparent temperature is the culmination of the radiation from all the objects which impact a particular target. When in the outdoor environment this includes the sky. This setting will vary from one place to another. It also has a bearing on the temperature readings which the camera displays.
In some instances, this variation may be insignificant. In some extreme instances though, the variation may be as large as 9°C or even more! When this is factored, an incorrect emissivity or the reflected apparent temperature could lead to the user recording temperatures to be lower than their true values.
Now try and imagine the consequences of such a low reading to a person who may have incorrectly signed off a piece of equipment as being safe or within acceptable limits. In case that piece of equipment was to go ahead and fail and lead to a fire outbreak due to this fault which had been overlooked, some serious implications may arise for that person.
This is particularly true if the specific report was scrutinized and the camera settings were established to have been faulty. Do bear in mind that insurance companies will always be on the lookout for any reason not to pay any compensation.
If the cameras can give out false readings, what is the use of implementing them?
The answer lies in the fact that you have to understand how to calibrate the camera correctly. You also have to look out for those areas or materials which will grant you the best temperature measurements and also offer accurate pieces of information to the clients.
Additionally, it is also necessary to comprehend how to carry out the analysis of the thermal patterns in order to determine the kinds of faults and the likely impacts that those faults may have on the other kinds of equipment.
There are various ways and means you can tackle this particular issue and also account for the impacts of reflections and the emissivity when conducting the survey. The information reveals that obtaining accurate readings go beyond merely buying a good camera, transporting it to the site, directing it to a particular target, and then shooting the image. There are lots of other issues that are involved in executing proper thermographic surveys irrespective of the nature of the application.
Obtain the Most out of your Investments by signing up for a training course
Whether you prefer buying or hiring a basic camera model or investing money in a top-of-the-range thermal camera, it is necessary to understand how best to operate it for your applications. This will see to it that you utilize the meaningful reports and prevent making any potentially dangerous mistakes. If you are buying a suitable thermal camera, always make a point of asking about relevant training for the sake of your applications.
A range of training courses does exist. These range from internationally recognized qualifications (Levels I, II & III) to one-day applications and introductory courses. They are designed to inculcate to you how to use the camera and avoid making any mistakes. These courses also cover how to set up a camera for the survey, what producing a report entails, and so much more.
Instrotech offers a range of one-day Thermography training course as well as the Level I & II qualification course. As a bonus, we can also offer to you some advice on both the application and selection of the best thermal camera in our capacity as a reviewer of the thermal cameras.
The full details of our training courses alongside the booking information are all available on our website. You will also find details of the various kinds of cameras available.