Relatively little investigation has previously been done on the effects of aging on conductor surface conditions, or on the ac corona discharges in the first 500kV compact transmission lines (Changping to Fanshan in Beijing) in China. In the present work these were investigated by means of comparing corona discharge on typical aged conductors with that on new ones. Scanning electron microscopy (SEM) and energydispersive X-ray (EDX) analysis were employed to characterize the surface morphology and composition of the conductors; and a non-contact surface profiler was used to measure the surface roughness of the samples. As a result of corrosion and the adherence of various substances to the conductors, the surface of operated conductor was rougher than the new one. The ac corona discharge characteristics of the conductors were studied in a corona cage using an ultraviolet imaging detector. As a result of the rough surfaces, the corona discharge intensity for the operated conductors was found to be stronger th an that for the new one; and the corona inception voltage for the operated conductor was 8.29% lower than the new one.
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