Reference Number
Please use reference number: SCEBE-21SF-029-AN
Background
Scotland, with considerable length of power transmission lines passing close to the shoreline, is very exposed to salt spray from the sea. The design and selection of outdoor insulators for overhead transmission lines is to a large extent based on their performance under contaminated and wet conditions. Under such conditions HV insulators are most vulnerable to external flashover. The contaminants deposited on the insulator surface can range from sea-salt to fertilizers, fly ash to cement dust, exhausts from factories and vehicles to chemicals used for de-icing streets. When the contaminant layer formed on the insulator surface becomes wet, the surface conductivity increases. This will cause increasing leakage current, initiation of partial discharge and under certain conditions, can lead to flashover and possibly power outage.
There is a widespread use of polymeric insulators because of their superior pollution performance. The surface hydrophobicity of these insulators makes them ideal for use in polluted environments especially in HVDC applications. Polymer insulators degrade by exposed to partial discharge and ultra violet radiation and erode due to dry band arcing resulting from pollution.
Fourier transform infrared spectroscopy (FTIR) of the samples enables us to detect bands related to the silicone and filler which provide information on the change in silicone and filler content. Raman spectroscopy will give bands at the same frequencies as IR spectroscopy but with different intensities due to the different selection rules. Furthermore, Raman microscopy offers mapping of the distribution of degradation products through the thickness of the sheds of the insulators. The surface morphology of the samples can also be studied using SEM (Scanning electron microscopy) after exposure to partial discharge. The aging performance of the insulator and the relationship between the stressed material and dielectric breakdown strength will be investigated.
Aims
The output of the project will improve knowledge concerning the aging of insulators and will lead to better manufacturing and design of insulators and consequently improving the reliability of power system. This will help also to increase the reliability of power transmission from marine renewable energy power plants. The continuity of supplying reliable energy to industries related to oil and gas is also vital and could be increased by relevant research in this area.
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