Corona loss tests on the 202-mile 60-cycle 220-kv. Pit-Vaca transmission line of the Pacific gas and electric company

A description is given of the physical and electrical characteristics of the Pit-Vaca 220-kv. transmission likely to affect corona loss. The line contains three distinct configurations and two sizes of conductor. Corona loss measurements were made from Pit Power House on the three configurations and from Vaca Substation on one of the configurations. Three methods of measuring corona losses were used at Pit and four at Vaca. The measured corona losses were found to follow exponential laws in three distinct phases; below visual corona, visual corona and visual corona with losses sufficiently high to produce voltage distortion. At no point did the losses follow a quadratic law. A review of the reports of the results of corona loss tests on other lines indicates that the corona losses followed exponential laws.