Feature Thermal Imaging Preventing failure and fire


Thermal imaging has become the industry standard method of spotting electrical faults in fully energised systems. It can spot early signs of failure and help to prevent fire, thus offering a huge benefit in the management of critical systems. FLIR Systems explain


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lectrical faults are responsible for approximately 35% of all indus- trial fires - resulting in massive financial losses of asset value and lost production. This is where thermal imaging can lend a helping hand as the technique can detect the anomalies that indicate fire risk. One company that is committed to the technology for this purpose is the European electrical contractor, EGI.


The company originally invested in a FLIR T360 infrared camera to meet its customers’ increasing demand for thermal inspection in line with insur- ance requirements. It is now common- place for insurance cover to be conditional upon regular thermal inspections in order to minimise both production losses and fire risk.


Ageing electrical systems EGI now counts large industrial com- panies amongst its list of customers for this service. Managing director of EGI, Michael Weigt, commented, “Control rooms can include up to 40 electrical cabinets and they have to be inspected every four years. This is not only stipulated by law but also required by insurance companies for fire prevention.”


In his view this approach makes a


intended. This requires immediate action as excess load can generate heat and pose a fire hazard.


Latest technology FLIR’s technology has become key to EGI’s operations and as such the company has recently upgraded its thermal imaging hardware to take advantage of the latest detection technology. It recently took delivery of a new FLIR T440, a key feature of which is Multi Spectral Dynamic Imaging (MSX).


Above: thermal imaging has


become a key tool in the management of mission


critical systems


lot of sense as old cable coating can become porous. External factors such as UV radiation can also cause changes to the plastic coating making it more brittle and prone to breakage. In addi- tion to this, contact points oxidise and fuses become overloaded.


The FLIR camera detects these problems immediately whilst the system is under load so their replace- ment can be scheduled during the next planned shutdown.


EGI also uses FLIR thermal imaging to detect asymmetrical loads and the reason for this is not always faulty modules. If an older system is extended over time, the upgraded elec- trical circuit can be exposed to a greater load than was originally


Detailed thermal images in real time is the clear benefit of MSX. It allows easier target identification without compromising temperature data. Unlike traditional thermal fusion that inserts a thermal image into a visible light picture, FLIR MSX embeds digital camera details into thermal video and stills. Indeed the images it produces are so clear there is no need for separate digital pho- tographs to be taken for reports. A 25 degree lens is standard with this camera but as EGI engineers often work in confined spaces, the company specified an additional, interchange- able 45 degree wide angle lens. Even when the distance to the electrical cab- inet is just 80cm, the wide angle lens provides clear detail and a complete image of the target area.


Connectivity


The FLIR T440 also introduced EGI to Meterlink. This makes it possible to transfer, via Bluetooth, the data acquired by an Extech clamp meter to


Improving pressure shock testing


test the reaction of different materials and component designs to oxygen at varying pressures and temperatures. Pressurised oxygen is widely used in chemical plants, iron ore smelting, hos- pitals and for scuba diving. However, the susceptibility of certain materials and component designs to large quantities of pressurised oxygen is highly unpre- dictable and can lead to strong reactions resulting in catastrophic failures. Traditionally BAM had used thermocouple sensors and spot pyrometers to


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measure temperature. However, these methods had limitations - thermocouples can be easily destroyed if there is a strong reaction with oxygen and spot pyrome- ters measure only temperature at one location. After investing in a FLIR SC Series thermal imaging camera, BAM researchers have been able to perform non-contact temperature measurements using an ‘oxygen pressure shock test’ methodology. In oxygen pressure shock testing the test material is finely divided to small flakes or grains, put into a stainless steel container and exposed to the pressurised oxygen. The FLIR SC-Series thermal imaging camera is used to detect the temper- ature rise on the outer surface of the container. Using the FLIR thermal imaging camera it is possible to detect a temperature rise which involves a chemical reac- tion of the material with oxygen. By performing these tests at different starting


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he Safe Oxygen Working Group at the Federal Institute for Materials Research & Testing (BAM) in Berlin, are using a FLIR SC-Series thermal imaging camera to


temperatures and at different oxygen pressures, potential reaction thresholds can now be accurately determined by BAM researchers.


The FLIR SC Series thermal imaging camera used at BAM contains an Indium Antimonide (InSb) Focal Plane Array (FPA) detector providing thermal images at a resolution of 320 x 240 pixels and a sensitivity of 13mK (0.013°C). This research grade camera is capable of capturing high contrast thermal images at a frame rate of 432Hz. For BAM oxygen pressure shock testing requirements, the FLIR SC Series camera was calibrated to accurately measure temperatures as high as 1,800°C.


SEPTEMBER 2013 Electrical Engineering


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