H. C. Barnes

Rational Analysis of Electric Fields in Live Line Working

As voltage of electrical transmission systems increases, live line maintenance by the barehand method becomes increasingly necessary to meet the requirements of system reliability. Of more importance is its value to the workman in permitting him to use power and hand tools without the strain which would be encountered with the long, heavy, hot line tools required at these voltages. Protection of the workman from exposure to high-voltage gradients and body currents is easily attained through Faraday cage-type shielding, as has been proved by an extensive test program described in this and companion papers. This paper develops a method of predicting voltage gradients and body currents utilizing both analytical and numerical techniques in the solution of Laplaces equation. The results are compared with field measurements and excellent agreement is obtained. The method described can therefore be used to predict both currents and gradients for new designs and voltage levels as well as for existing designs and voltages.

Exposure of Mice to a Strong AC Electric Field - An Experimental Study

Twenty-two male mice were exposed to a 60-Hz ac electric field by placing them, in cages, between parallel plates energized to create a field, initially unperturbed, of 4 kV/in. In the course of 10?months, each animal had an accumulated exposure time of nearly 1500 hours. These animals, and a parallel control group (essentially identically handled but receiving no exposure to electric fields), were repeatedly bred and observed to determine whether there were any effects, harmful or beneficial, as a result of the exposure.

Body Currents in Live Line Working

A series of tests have been conducted at 138 and 345 kV to determine field intensities and body currents to which live line transmission linemen are subjected in various methods of working. These tests confirm that field intensities and body currents encountered in present practices, for the methods and voltages of the tests, are well below the threshold of feeling and perception. With still higher voltages, body currents can be maintained at acceptably low levels by means of adequate shielding, for any method of working.

UHV Transmission Design Requirements - Switching Surge Flashover Characteristics of Extra Long Air Gaps

This paper presents data on performance of air gaps of up to 29 meters, which is beyond any previously reported. The data is raw data without any endeavor being made to compensate for the many atmospheric variables which could affect the results. However, many of these atmospheric conditions were recorded and are reported herein for future analysis and comparison with the results from other test projects.

Preliminary Analysis of Extensive Switching Surge Testing of American Electric Power's First 765 KV Line and Stations

A series of 159 switching operations and other tests were made on AEPs first 765 kv line and stations to be placed in service. Extensive data was obtained and compared with design data in the areas of switching surge overvoltage generation under varied conditions, methods -for limiting overvoltages, characteristics of equipments, and radio interference and audible noise. The results of the initial analysis of this data are presented here.

AEP 765-kV System: General Background Relating to Its Development

The decision to introduce 765 kV on the American Electric Power (AEP) system is related to the general development of EHV transmission in this country and abroad. In 1952 AEP pioneered in developing 345-kV transmission as an overlay to the then existing 138-kV system and is now pioneering in the development of 765-kV transmission as an overlay to both the 345- and 138-kV systems to assure a fully integrated operation. Load growth, reliability, prudent use of land and rights-of-way, and economics of EHV transmission are discussed as related to the decision to construct the 765-kV system.

Alternator-Rectifier Exciter for Cardinal Plant 724-MVA Generator

This paper covers American Electric Power Service Corporations selection of an alternator-rectifier excitation system for the two 724-MVA generators for Cardinal plant. It also reviews the experience with the shaft-driven exciters installed since 1952. Several alternate excitation systems were studied which led to the selection of the new Alterrex excitation system which is described in detail.

The Apple Grove 750-kV Project- 500-kV Switching Surge and Line Flashover Tests

Rational design of extra-high-voltage systems depends on analytic studies to predict switching surge overvoltage magnitude and probability, and on laboratory tests for tower system switching surge withstand capability. Laboratory tests have been confined to ideal waveforms applied to single window configurations. Correlation with flashover performance of a typical 3-phase installation exposed to actual switching surge waveforms is attempted. The influence of interphase coupling and multiple circuit breaker operations in promoting multiphase flashover, which may curtail system performance margins, is also studied.

A New Shunt Reactor Principle Proved: Designed Data and Factory Test Results for Units Built on The Insulated Core Principle

Effective control of electrostatic as well as electromagnetic field distribution within EHV transformer-type equipments significantly enhances their on-line performance. This paper describes the first application of the insulated core principle for management of fields of a 765 kv shunt reactor installed on the AEP System. Design techniques and ta are presented and the modular concept of reactor construction in an oil-filled device is described. Results of feasibility studies of reactors for future UHV systems are included.

Nonlinearity in Impulse Breakdown of Very Large Air Gaps

Optical and electrical measurements of positive impulse discharges, in a point-to-plane electrode configuration, have been performed for electrode spacings ranging from I to 7 meters. A comprehensive analysis of these results indicates that the breakdown mechanism above 5.2 million volts (MV) differs from the mechanism operating at voltages below this level. A new extrapolation method for breakdown voltages levels above the measurable range has been developed. This method permits the determination of positive impulse breakdown voltage for very large gap spacings up to 14 meters, well above the maximum capabilities of presently available voltage sources. This study provides essential data contributing to a feasibility study of future UHV overhead systems.