Comparison of calculated and measured corona loss curves

Corona loss curves made on a number of experimental and practical lines by different investigators have been corrected and plotted. The loss has been calculated by the quadratic law for each case under the same conditions as to spacing, conductor diameter, altitude, etc. and plotted for comparison. It is of interest to note that the measured values were made at various parts of the country. The time period covers a number of years and the altitude varies from sea level to 10,000 ft. An exact check of calculated and measured losses cannot be expected, as the exact conditions are not always known as to conductor surface, wave shape, etc. Such losses are also difficult to measure, especially on practical lines where the voltage range is quite small and there are a large number of corrections to make. The check is as close as the accuracy of the measurements permit. The variations from the calculated values are in most cases due to the fact that practical measurements have been made on the unstable part of the curve below the visual critical voltage value. The losses at this part of the curve are fully discussed.