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FeuerTRUTZ-International-2-2016

TECHNOLOGY AND TRENDS Even thermally conspicuous cells, modules or inverters of PV solar systems are detected quickly. Source: FLIR Systems the IR camera and the resolution of the IR detector that detects the heat radiation. The higher the detector resolution, the more details that you are able to recognise. The resolution with standard cameras is currently at 320 × 240 IR pixels, that corresponds with 76,800 individual temperature measurement values. More details can be recognised with a higher resolution IR camera with 640 × 480 or 1.024 × 768 IR pixels. A further important camera parameter is the temperature range detected that, depending on the application, should be between –40 and +250 or +750 °C or more. Furthermore, the thermal sensitivity, also specified as NETD value is important. Overheated electric components can particularly lead to a significant hazard source and cause fires. Source: FLIR Systems This value specifies the smallest temperature difference that can be detected by the detector and with professional cameras´, is between 0.03 and 0.05 Kelvin at 30°C. The geometric resolution (IFOV value) also decides about the measuring accuracy. It depends of the lens currently being used and defines the smallest possible measuring spot size. That is the surface on the measuring spot that can be assigned in a thermal image by an individual detector cell from a distance of 1 m. The measuring spot size decides about how accurate the measurement will be with a present lens size or distance. That is decisive in particular with faraway objects (high-voltage current thermography) respective fine structures (electric / electronic) components. Depending on the spacious situation or distance to the object, the camera lens must be replaced by a wide angle or telephoto lens relating to the task. For the setting options of the camera, at least the emission level (material-specific heat radiation characteristic value) of the measuring object as well as the reflecting temperature must be included. The person operating the camera also decides about the quality of the measurement. Beyond knowing the correct operation of the camera, the user must know possible error sources and the limits of thermography as well as be able to interpret the measuring results. This requires knowledge in the areas optics, heat radiation, heat conduction, measuring technology, material science, building science when taking the pictures as well as when evaluating them, as well as technical knowledge relating to the measurement object. Knowledge about the materials used, the technical and constructive structure of the respective measurement object are also essential as they help with the interpretation of thermal abnormalities. Moreover, in advance, the camera operator must familiarise themselves in detail with the function and thermal characteristics of the system to be examined as well as with possible faults. An important factor in thermography is the resolution as cameras with higher detector resolution measure more accurately – comparison of the detection formats 160 × 120 IR pixels (left) and 1.280 × 960 IR pixels (right) as well as the measured values. Source: InfraTec 20 FeuerTRUTZ International 2.2016


FeuerTRUTZ-International-2-2016
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