During the lifelong maintenance of low-voltage electrical installations in any facility special attention must be given to firecausing failures, which cannot be detected by conventional protection devices (miniature circuit breakers, fuse-links, residual current devices, etc.). Such failures are most often caused by poor electrical contacts. International regulations and standards, which define periodic verification of the quality of low-voltage electrical installations, do not contain procedures by which a poor electrical contact would be detected at an early stage. However, one of the techniques used for this purpose today is performing preventive thermographic inspections (a standard covering this area is available only in the USA). By such inspections a poor electrical contact which creates prerequisites for the occurrence of an initial fire in a low-voltage electrical installation can easily and effectively be detected. Detected failures and irregularities can most frequently be eliminated by simple interventions of electricians or facility technical services. Experience from a large number of periodic verifications of the quality of low-voltage electrical installations in industrial and administrative facilities, conducted by personnel of the Laboratory for testing low-voltage electrical and lightning protection installations at the School of Electrical Engineering in Belgrade, showed that many dangerous failures would not be detected without performing preventive thermographic inspections. Several practical examples of such failures, detected in low-voltage electrical installations in industrial and administrative facilities during preventive thermographic inspections, are presented and analysed. The procedure of performing preventive thermographic inspections within periodic verifications of the quality of low-voltage electrical installations, as well as the explanation for proper interpretation of the measurement results based on the ΔТ and absolute temperature criteria, are also given in this paper.
- N. Hadziefendic, N. Kostic, J. Trifunovic, M. Davidovic, I. Zarev, Fire caused by faults in electrical installations – statistical data and fault review, in: Proceedings of V International Regional Conference Applied Protection and Its Trends, 48–62 (2018), Zlatibor. (in Serbian)
- Low-voltage electrical installations – Part 6: Verification, document IEC 60364-6 (2016).
- N. Hadziefendic, J. Trifunovic, N. Kostic, M. Kostic, Analysis of influence of poor contacts in the electrical installations on fire hazard, Tehnika, 68, 81–87 (2013). (in Serbian)
- I. Zarev, N. Hadziefendic, Detecting serial arc in low-voltage electrical installations using modern protective components, Tehnika, 69, 637–644 (2014). (in Serbian)
- А.S.N. Huda, S. Taib, Application of infrared thermography for predictive/preventive maintenance of thermal defect in electrical equipment, Appl. Therm. Eng., 61, 220–227 (2013).
- D.B. Durocher, D. Loucks, Infrared windows applied in switchgear assemblies: taking another look, IEEE T. Ind. Appl., 51, 4868–4873 (2015).
- Standard for infrared inspection of electrical systems & rotating equipment, Infraspection Institute, 425 Ellis Street, Burlington, NJ 08016 (2008).
- N. Hadziefendic, M. Kostic, J. Trifunovic, Thermal imaging of poor contacts and AFCI technique for series arc breaking, in: Proceedings of II Fire Safety Consulting, 25–42 (2012), Belgrade. (in Serbian)
- Maintenance testing specifications for electric power distribution equipment and systems, ANSI/NETA (2011).
- A.A. Sarawade, N.N. Charniya, Infrared thermography and its applications: a review, in: 3rd International Conference on Communication and Electronics Systems (ICCES), 280–285 (2018), Coimbatore.
- R.A. Osornio-Rios, J.A. Antonino-Daviu, R.J. Romero-Troncoso, Recent industrial applications of infrared thermography: a review, IEEE T. Ind. Inform., 15(2), 615–625, (2019).
- J. Lukovičová, G. Pavlendová, Determination of heat transfer coeficient by inverse heat transfer analysis with thermographic experiment, Machines. Technologies. Materials., 9(2), 17–19 (2015).
- S. Prokhorenko, K. Maś, M. Woźny, E.M. Sheregii, The scaning nozzle hot air system for thermographic detection of the surface incorporated hidden defects, Machines. Technologies. Materials. 8(11), 49–51 (2014).
- D. Todorov, P. Mashkov, B. Gyoch, N. Mihaylov, A study on thermal performance of LED signal heads using infrared thermography, Trans Motauto World, 2(1), 33–36 (2017).
- K. Maś, M. Woźny, M. Marchewka, D. Płoch, E.M. Sheregii, The termographic analysis of the welding by TIG, Machines. Technologies. Materials., 8(11), 46–48 (2014).
- R. Usamentiaga, M.A. Fernandez, A.F. Villan, J.L. Carus, Temperature monitoring for electrical substations using infrared thermography: architecture for industrial Internet of Things, IEEE T. Ind. Inform., 14(12), 5667–5677 (2018).
- J.V.P. Oliveira, A.L.F. Coelho, L.C.C. Silva, L.A. Viana, A.C.V. Pinto, F.A.C. Pinto, D. Oliveira Filho, Using image pre-mapping for applications of monitoring electrical switchboards, Automat. Constr., 112, 103091 (2020).
- J. Wang, C. Zhao, Broad learning system based visual fault diagnosis for electrical equipment thermography images, Chinese Automation Congress (CAC), 1632–1637 (2018), Xi'an.
- H. Cong, H. Jin, Research on undetected overheat fault of the GIS bus bar contacts based on infrared thermal imaging, J. Electr. Eng. Technol., 14, 839–848 (2019).
- S.Y. Lee, S.S. Teoh, A survey on infrared thermography based automatic electrical fault diagnosis techniques. In: 10th International Conference on Robotics, Vision, Signal Processing and Power Applications, 537–542 (2019), Singapore.
- Expert reports for periodic verifications of the quality of low-voltage electrical installations in industrial and administrative facilities, issued by the Laboratory for testing low-voltage electrical and lightning protection installations at the School of Electrical Engineering in Belgrade (2015–2019). (in Serbian)
- N. Djenic, I. Zarev, N. Kostic, N. Hadziefendic, J. Trifunovic, J. Zivanovic, The importance of early detection of electrical failures as a potential cause of fire by means of thermal imaging, in: Proceedings of VI Risk Management Counselling, 65–80 (2018), Pozarevac. (in Serbian)
- Low-voltage electrical installations – Part 5-52: Selection and erection of electrical equipment – Wiring systems, document IEC 60364-5-52 (2009).
- A.E.F. Taylor, Electronic ballasts: Non-dimming electronic ballasts for 4-foot and 8-foot fluorescent lamps, National Lighting Product Information Program (NLPIP) Specifier report, 8(1) (2000).