Using the Ultra Violet spectral range for predictive maintenance in electrical utilities becomes resourceful once inspectors are fully aware of the environmental, structural and physical considerations involved. Ultra Violet radiation, as perceived where corona and arcing superficial partial discharge occur, has unique patterns that need to be understood during inspection. Apparently, to be able to perceive the UV radiation during daytime, an optical sensor and a solar blind filter are needed, or better yet: dedicated solar blind corona cameras as manufactured by Ofil. Ofil has furthermore simplified the process of seeing-corona and turned UV inspection into a feasible and beneficial procedure.

Ofil’s flow chart walks inspectors through major hierarchical nodes where questions and the corresponding answers lead to following steps. Once all nodes are crossed, a prognosis is conceived as well as decisions of what actions need to be taken to maintain the health and reliability of the inspected facility. But, to be able to cross the nodes, it is needed to be able to see the corona discharge and its severity. Usually, the severity of the corona is expressed in counted units and displayed by Ofil’s corona camera. This feature is directly related to the camera’s optical UV sensor and the ability to filtrate and block sun light. Indeed, only very sensitive apparatuses such as Ofil’s corona cameras can provide such capabilities.

In general, the inspection procedure as reflected in Ofil’s flowchart starts once corona is detected by the DayCor® and its location is clearly seen. The first argument maintenance engineers need to attend to is about the corona location. Engineers will be asked whether the spotted location is critical before moving to the next question which considers the physical and chemical attributes of the emissive source. The severity of the corona, as indicated by the corona camera and the answers accumulated along-the-way are then linked towards a final diagnosis. Combining the corona strength, as DayCor® indicates, its location and material considerations with the ambient conditions of temperature and humidity yields alerts and guidelines to priority scheme and to predictive maintenance management.