Abstract
Substation connectors, like many other high-voltage products, are tested once manufactured. However, the corona behavior of aged specimens can differ from that exhibited by newer ones, thus generating detrimental technical and environmental effects. Manufacturers need to know the long-term corona behavior of substation connectors to offer their customers maximum safety and transparency about such critical products. This paper analyzes the ageing effect on the surface roughness and the visual corona extinction voltage of sand-cast aluminum connectors, which were artificially aged in a salt spray chamber for different periods. The experimental results show an important variability of the surface roughness and corona extinction voltage (CEV) among connectors with the same ageing level due to the sand-casting manufacturing process. The results in this paper also show a slight increase in the surface roughness with the ageing period, although there is not a clear pattern between the applied ageing level and the experimental CEV value. It is concluded that the inherent variability among connectors due to the sand-cast process has more influence than the ageing effect itself.
Highlights
Corona is a partial discharge in air that occurs under a non-uniform electric field [1] close to the areas of highest electrical stress of high-voltage electrodes such as conductors or connectors when the electric field strength exceeds a threshold value [2]
Bian et al analyzed the audible corona noise generated by aged transmission line conductors, concluding that they generate more noise compared to new conductors, especially during light rain and foggy weather [2]. It seems that surface condition can play an important role on corona activity of high-voltage conductors [18], since surface roughness can reduce the insulation strength of the high-voltage electrode due to the changes produced in the macroscopic electric field distribution [19], electrode geometry plays a leading role
The combination of porosity, poor surface finish, greater surface roughness, and low dimensional accuracy can play an important role on corona performance of new and aged sand-cast substation connectors, so it is worthy of investigation
Summary
Corona is a partial discharge in air that occurs under a non-uniform electric field [1] close to the areas of highest electrical stress of high-voltage electrodes such as conductors or connectors when the electric field strength exceeds a threshold value [2]. Bian et al analyzed the audible corona noise generated by aged transmission line conductors, concluding that they generate more noise compared to new conductors, especially during light rain and foggy weather [2] It seems that surface condition can play an important role on corona activity of high-voltage conductors [18], since surface roughness can reduce the insulation strength of the high-voltage electrode due to the changes produced in the macroscopic electric field distribution [19], electrode geometry plays a leading role. The combination of porosity, poor surface finish, greater surface roughness, and low dimensional accuracy can play an important role on corona performance of new and aged sand-cast substation connectors, so it is worthy of investigation.
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