Effects Of Lightning Research Articles

The Direct Effects of Lightning on Aircraft

Protection of aircraft against the physical-damage and fuel-vapor ignition hazards of lightning has long been a concern of aircraft designers. These hazards are now referred to as the direct effects and include the damage that may occur at the lightning-attachment spots on the aircraft, as well as the possibility of electrical sparking that may occur within fuel tanks. As aircraft design have changed, new methods to protect the aircraft against these have had to be developed. This need is expecially true with respect to structures made of fiber-reinforced plastics and other non metallic materials, which are often more vulnerable to damage than conventional aluminum structures. In this paper, we review the potential hazards, protection methods and some of the test techniques available for design verification.

Project aims to improve weather predictions

Project Skywater, an atmospheric research program slated to begin this spring, will investigate basic precipitation problems, including the formation of raindrops, mechanisms by which air outside rainclouds mixes with air inside, atmospheric processes that lead to the birth and growth of a storm, and the origins of ice. These fundamental problems ‘stand in the way of evaluating the potential of weather modification techniques and of predicting precipitation and severe weather,’ according to Bernard A. Silverman, project head.As part of the project, researchers will work this summer on the Cooperative Convective Precipitation Experiment (CCOPE). Based in Miles City, Montana, CCOPE will study the lifetimes of summer clouds. The work will focus on the major natural processes that lead to precipitation in large cloud systems. In addition, researchers will investigate cloud chemistry and lightning's effect on rainfall.

Submicrosecond risetimes in lightning return‐stroke fields

Measurements of lightning electric field, E, and dE/dt signatures have been made near Tampa Bay, Florida, under conditions where the lightning locations were known and where the results were not significantly affected by the response time of the measuring system or ground‐wave propagation. The fast transitions found on the initial portion of return‐stroke fields have 10‐90% risetimes ranging from 40 to 200 ns, with a mean of 90 ns. The maximum field derivatives during return strokes range from 5 to 75 V/m(µs)−1 with a mean of 29 V/m(µs)−1 when normalized to a distance of 100 km. These field risetime and derivative values suggest that return‐stroke currents contain large, submicrosecond components, and this in turn suggests that it may be necessary to reevaluate the possible effects of lightning and the performance of lightning‐protection devices in many situations.

Visual observations from space

Visual observations from space reveal a number of fascinating natural phenomena of interest to meteorologists and aeronomists, such as aurorae, airglow, aerosol layers, lightning, and atmospheric refraction effects. Other man-made radiation, including city lights and laser beacons, are also of considerable interest. Of course, the most widely used space observations are of the large-scale weather systems viewed each day by millions of people on their local television. From lower altitudes than the geostationary meteorological satellite orbits, obliques and overlapping stereo views are possible, allow height information to be obtained directly, often a key element in the use of the photographs for research purposes. However, this note will discuss only the less common observations mentioned at the beginning of this paragraph.

Research on Artificiallyu Triggered Lightning in France

An experimental station for research on lightning and lightning effects was built in the Massif Central (France) in 1973. The experimental procedure is an application of artificial triggering of lightning flashes by means of the wire and rocket technique, which has previously been shown to be valid by M. M. NEWMAN.

Multiple-Pin Connector with Internal Surge Protection

The design and performance characteristics of a multiplepin electronic surge arrestor (Bulk ESA) are described. This device is a simple, compact unit providing electromagnetic pulse (EMP) and lightning protection of systems in which many signal lines enter sensitive electronic equipment. Basically since it takes one device to protect each wire entering a system, the efficient packaging of the Bulk ESA provides a surge arrestor which has the advantages of space saving, low cost, and simplified assembly over the use of cuffent protective devices which range from diodes to large spark gaps. The multiple-spark-gap (Bulk ESA) protector developed is a sealed chamber containing 53 inline spark gaps. Each end of the chamber contains a standard 53-pin connector. The sealed chamber is filled with argon gas at 12-mm pressure, to which a trace of radioactive gas is added to stabilize the breakdown and enhance the fast-rise response. The Bulk ESA can be integrated with an EMI filter-pin connector which, in turn, can improve the performance of the Bulk ESA. These two assemblies provide a method to help protect against EMP, lightning, EMI, and TEMPEST effects

金属構造物と防食系に対する交流と雷の影響の軽減に関する推奨施工法

金属構造物と防食系に対する交流と雷の影響の軽減に関する推奨施工法

On the Use of Tailored Return-Stroke Current Representations to Simplify the Analysis of Lightning Effects on Systems

Considerable siniplification is possible in the analysis of the interaction between a lightning return-stroke current and a system by selecting a return-stroke current representation whose Laplace transform has the same general form as the transform of the system transfer function.

Effects of Electricity and Lightning on Man and Animals

Abstract It is often difficult to prove whether a man or animal has been electrocuted. Since death from electrocution can occur with no marks on the body, it is important for pathologists and attorneys to be aware of the lethal effects of electricity from the viewpoint of the engineering expert witness who aids in the investigation of such cases.

Diameter of lightning as indicated by tree scars

During a study of lightning effects on forest trees in western Montana, I observed that some lightning scars showed both millimeter-width and centimeter-width mechanical damage along the affected tree trunks [Taylor, 1962]. Similarly, Oman [1964] reported that lightning melted both millimeter-class and centimeter-class holes in fiberglass boots that he had attached to lightning rods. He obtained diameter estimates of several lightning strokes in this manner. Uman's report prompted a recent re-examination of the type of tree scar observed in the earlier study. In this note I describe the scar type and discuss its possible relation to the diameter of lightning.

Five-Year Field Investigation of Lightning Effects on Transmission Lines I-Data Summary and Suggestions for Improved Line Performance

A 5-year field investigation of lightning-stroke characteristics and effects on transmission lines was conducted by means of kineklydonographs (KKs) and other instruments. Results disclosed that characteristics differ in several important respects from previous concepts still widely accepted, and therefore warrant a new survey of line design practices leading to suggested methods for improvements. The initial rates of rise of stroke current are much steeper than is generally believed and tend to be uniform, independent of the current crest. This emphasizes the importance of low tower surge impedance, low tower height, multiple ground wires, and counterpoises. Induced voltages also appear to be more significant than previously believed and, hence, may merit preventive measures.

Five-Year Field Investigation of Lightning Effects on Transmission Lines II-Instrumentation and Installations

In the transmission-line study, masts were attached to the tower tops, connected to the towers by resistors, around which were connected kineklydonorgraphs (KKs). Only mast current, if struck, was recorded in the beginning. Later, ground wires were insulated from the towers in several installations, but were again connected to the towers through resistors shunted by KKs. Information on characteristics of currents in strokes to the masts was thus recorded, as were currents from ground wires to towers and vice versa. Large current changes in time intervals of 0.05 ?s were registered. Electric field gradients, the occurrence of nearby strokes, and corona currents were recorded also. Five utilities in Illinois, Ohio, Pennsylvania, and New York participated. A tall building in Pittsburgh, surmounted by a 50-foot insulated mast, was equipped with all the recording devices used by cooperating companies.

Five-Year Field Investigation of Lightning Effects on Transmission Lines III-Lightning-Stroke Characteristics and Their Effects in Transmission Systems

Seventeen negative strokes to transmission towers and the Cathedral of Learning (CL) in Pittsburgh, Pa., have been recorded. The crest currents ranged from 11 to 50 kA. Only one positive stroke of 80 kA appeared; it was at the CL. The greatest rate of change of stroke current recorded was 230 kA/μs during an interval of 0.05 μs. All stroke currents had approximately the same rate of rise during given time intervals. Measurement of ground wire current enabled determination of tower-top potentials which resulted almost entirely from the tower surge impedance, since tower footing resistances were low. There is evidence that induction from passing leaders and strokes to earth nearby will produce high voltage on exposed conductors. Records of field gradients accompanying nearby strokes showed as much as 120 kV/m.

Investigation of electron runaway in lightning

Electron-sensitive photographic emulsions were placed at points where lightning strokes occurred to a 300-m tower. No tracks of high-energy electrons, which might be associated with lightning, were observed. A search for radioactivity also showed no effects of lightning. (auth)

Design of An Extra-High Voltage Transmission Tower 100 Feet High

Prestressed concrete transmission towers for 400 to 750 kV are now in operation at the extra-high voltage research project. Radio noise tests; lightning effects; structural design of tower; tower configuration; design considerations; foundations; fabrication and shipping; and erection are described.

Survey and Classification of Publisled Data on the Surge Performance of Transformers and Rotating Machines

Many theoretical and experimental studies have been made since the beginning of this century on the problem of the surge performance of transformers, rotating machines, air coils, current-limiting reactors, etc. This work has led to a clear understanding of the effect of lightning, switching surges, and impulse voltages on stations and substations and on the apparatus included in them. It has also led to the introduction in all countries of insulation co-ordination, standard impulse tests, and rational protective practices. This, in turn, has achieved the result that properly designed and properly protected apparatus are now practically immune to the abnormal voltages arising during service conditions. Despite these achievements, certain aspects of the problem, both theoretical and experimental, yet remain to be solved, and work is actively progressing in this field in many countries. This paper presents a historical survey of the problem, the solutions which have been devised, and the present status of the art. It analyzes the work done in various areas through a comprehensive review of significant contributions to literature. It is hoped that this review will enable interested engineers to gain a full understanding of the problem, to be used as a basis for future original contributions in this important and fascinating field of electrical engineering. (All superscripts refer to the references listed in reference 1. The first two digits refer to the year of publication, with 19 omitted.)

Lightning protection on the stevens point--Wisconsin rapids intercity telephone cable

It has been a common assumption that buried telephone cables are practically free from the destructive effects of lightning, particularly intercity cables which have no intermediate terminals or connections to local subscriber installations along the route of the buried section. Such cables in some areas, however, have been found to be relatively vulnerable to damage from lightning strokes occurring along the route of cables. To avoid such damage various methods have been employed. One method has been to plow shield wires in the ground above the location of the cables. Whether or not such protection is provided is customarily based on balancing the cost of such measures against the expectancy of lightning strokes per year along the respective route, and the anticipated cost of repairs and interruptions entailed. This paper describes a situation where the anticipated troubles did not appear to warrant the cost of the initial installation of shield wires, but later experience indicated the need for some remedial measures. The measure adopted consisted of the installations of full-count carbon gap protection at various intervals along the cable route.

The penetration of surge voltages through a transformer coupled to an alternator

Most modern transmission systems operate at 66kV or higher voltage and are supplied from alternators whose voltage is stepped up by transformers, and when considering the effect of transmission-line lightning surges on a power station it is necessary to regard the transformer and alternator as a single unit.After a brief analysis of the phenomena likely to be produced when an impulse voltage is applied to a transformer coupled to an alternator, the results are confirmed by tests on three such units. These show that the principal transfer of voltage through the transformer is due to magnetic coupling between windings and causes an oscillatory voltage to be superimposed on the surge voltage in the l.v. winding. In addition, the distributed capacitance and inductance between the windings of the transformer cause an electromagnetic transfer of voltage with travelling waves in both the transformer and alternator windings.Approximate empirical methods are given to calculate the transformer h.v. voltages from the various circuit parameters. The results are compared with those obtained from the tests.Since in practice the transformer and alternator are excited at power frequencies, whenever a surge is likely to reach the windings it is necessary to allow for this in estimates of the voltages which may occur at the alternator terminals. On the assumption that the surge protection for the unit consists of a rod-gap or other voltage-limiting device at the transformer h.v. terminals, an analysis is made with a view to ascertaining the maximum voltage which may occur at the alternator terminals. In a typical case this is shown to add about 10% to the potential expected without allowing for the power-frequency excitation.

Lightning-A Hazard to Electric Systems [includes discussion

The first phase of the problem of lightning protection of power systems from the damaging effects of lightning has been completed. A working knowledge of the parameters of the transients which may be applied to lines or apparatus as the result of lightning storms is now available from studies of natural lightning and its effects in various parts of the world through the use of devices especially designed for the purpose.

Lightning protection on the South African electrified railways

After describing the lightning conditions which exist in the South African electrified-railway areas, the paper deals with the practical aspects of lightning protection as applied to electric locomotives, electric motor-coaches, overhead track-equipment and traction substations associated with 3 000-volt d.c. electrified systems. A brief history of the early difficulties experienced and the measures taken to overcome them is given, and Tables are included indicating the actual results obtained from various protective devices. Finally, the author's conclusions are appended as to the most satisfactory means of protecting each section of a 3 000-volt d.c. electrified system.No account is taken of lightning effects on the extra-high-voltage transmission lines associated with the substation supplies as this subject is common to all high-voltage transmission systems and has been covered in other papers.