This paper describes Bonneville Power Administration's basic philosophy for predicting audible noise from ac and dc high voltage transmission lines. General formulas for predicting the A-weighted audible noise during rain for ac lines and during fair weather for dc lines which were developed from data from full-scale lines are presented. From this basic calculation, audible noise cumulative distributions, frequency spectrums, and lateral profiles can be estimated

Formulas for Predicting Audible Noise from Overhead High Voltage AC and DC Lines

In the paper is presented a smmary of cage measurements of the radio interference, the audible noise, and the corona losses for a large number of conductors and conductor bundles. The analysis of the test results obtained also leads to the establisment of a theoretical method of predicting the corona performance of conductor bundles, based on experimental data obtained with single conductors and taking into account the actual distribution of the field strength at the surface of individual sub-conductors in the bundle. Some cases of practical interest are discussed with reference to the effect of conductor aging and the asymmetry of the bundle configuration. Application of the theoretical method to the prediction of the corona performance of long three-phase lines, taking the actual field distributions at the center and outer phase conductors into account, is also discussed.

A method of predicting the corona performance of conductor bundles based on cage test results

This paper summarizes the results of two extensive literature reviews on the biological effects of electric fields from EHV transmission lines. While considerable data exist on this subject major problems were found in much of the literature. It was found that electric field induces about the same body cuirent into humans as that experienced by individuals touching household appliances. As a consequence, the electric field environment from EHV lines is only a subset of the ubiquitous 50-60 Hz electromagnetic environment found throughout industrialized communities. The omission of such environmental considerations has limited the usefulness of a number of studies. A lack of understanding of how electric fields couple energy into animals has resulted in inconclusive research or inappropriate interpretation of results. A common misinterpretation has been to extend experimental results observed for fish or quadrupeds to erect humans on a simplistic volts-per-meter exposure basis. While some of the studies reviewed noted potential deleterious effects at likely field levels for animal subjects, none of these reported effects could be unequivocally attributed to direct effects of the electric fields, In these cases the studies did not adequately consider the influence of competing factors in the test environment or biological procedures which could cause the same effect. Such neglect represents a major obstacle in attempting to evaluate the results of these studies.

Biological influences of power frequency electric fields&#8212;A tutorial review from a physical and experimental viewpoint

This paper describes the transmission lines that have been built throughout the world to operate above 700 kV. The paper provides information on the system planning, the electrical design, the mechanical and tower design, and the operation and maintenance experience of lines built in the U.S., Canada, South Africa, Brazil, Venezuela, Russia, Korea, India and Japan. Also briefly discussed is the research conducted around the world to develop systems to operate above 700 kV including the research conducted by EPRI at their high-voltage research facility in Lenox, Massachusetts

Overview of transmission lines above 700 kV

Audible noise produced by corona during foul weather is an important consideration in the design of high-voltage transmission lines. The measurement, analysis and prediction of audible noise and the assessment of noise reduction techniques have constituted a primary area of research at Project UHV. Results of earlier short-term testing utilizing single-phase test facilities have, since 1975, been greatly augmented by longer-term field data obtained on a three-phase test line. This paper presents the results of a portion of this work The effect of the weathering or aging of conductors on noise levels is examined and the effectiveness of the concept of asymmetric conductor bundling for noise reduction is assessed.

Audible Noise Performance of Regular and Asymmetric Bundles and effect of Conductor Aging on Project UHV's Three-Phase Test Line

This paper presents the results of a statistical anaylsis of conductor corona generated audible hoise as measured at the Apple Grove 750 kV Test Project, a joint field investigation sponsored by the American Electric Power Service Corporation and the Westinghouse Electric Corporation. A comparison of simultaneous audible noise data is made on three sizes of four conductor bundles [diameter of 1.382 in. (35.1 mm), 1.196 in. (30.4 mm), 1.0 in. (25.4 mm)]. Also a correlation is given of simultaneous readings of audible noise, radio noise and corona loss.

The Apple Grove 750 kV Project Statistical Analysis of Audible Noise Performance of Conductors at 775 kv

This paper presents wind-tunnel measurements of ozone and NOx production rates for single and bundle transmission line conductors in dry and wet corona. Ozone production rates reported in the literature for transmission line and fine wire corona, together with the authors' results are summarized as a function of the maximum surface gradient factor. Numerical calculations estimating the ozone levels near actual 775-kV test transmission lines at the Apple Grove 750-kV Project are presented. It is concluded that pollutant concentrations generated by conductor corona on present EHV transmission lines are too low to be deleterious to the environment.

Experimental Oxidant Production Rates for EHV Transmission Lines and Theoretical Estimates of Ozone Concentrations Near Operating Lines

This paper presents the results of a study of transmission line ozone conducted in January 1975 at the Apple Grove 750 kV Project. Ozone measurements using chemiluminescent monitors were made adjacent to the C-line test span which operates at surface gradients much higher than commercial lines. Simultaneous measurements were made of corona loss and wind parameters. Ozone was monitored at two fixed sampling stations located 30 feet and 2 feet above ground 95 feet from the center phase at midspan. Ozone due to line corona was detected only at the 30 foot station and only in foul weather. In fair weather line ozone could not be detected at either station. An ozone production rate of 2.4 g/ kWhr was deduced for the C-line in foul weather corona. A diffusion analysis was carried out to predict ozone concentrations near a normal 765 kV line for a hypothetical worst case situation. It is concluded that ozone production by a normal 765 kV line has an insignificant impact on the environment.

Ozone Concentration Measurements on the C-Line at the Apple Grove 750 kV Project and Theoretical Estimates of Ozone Concentrations Near 765 kV Lines of Normal Design

There is growing evidence that some service outages, in or immediately adjacent to the splice sleeves of heavily loaded EHV pipe-type cable lines, were associated with thermo-mechanical bending. This evidence, plus an additional instance of trouble induced by a mechanical mechanism in the EPRI-Manufacturers 550-kV Waltz Mill test program1, prompted a follow-up study. This paper reports on a project designed to assess the effect of cyclical cable movement on the paper-oil dielectric of Cable A, with conductor temperatures reaching as high as 130°C. A detailed examination of the cable after the loading schedule had been completed, revealed no evidence of significant displacement or damage to the paper tapes which would affect the service life of the cable. This work has been funded by the Electric Power Research Institute as a portion of their comprehensive program on underground transmission.

F. M. Dietrich

Papers

The Apple Grove 750 kV Project Statistical Analysis of Audible Noise Performance of Conductors at 775 kv

Experimental Oxidant Production Rates for EHV Transmission Lines and Theoretical Estimates of Ozone Concentrations Near Operating Lines

Ozone Concentration Measurements on the C-Line at the Apple Grove 750 kV Project and Theoretical Estimates of Ozone Concentrations Near 765 kV Lines of Normal Design

Mechanical Effects Load Cycling on Pipe-Type Cable