Lightning and other transients on transmission lines

A great many uncoordinated researches and observations have been made of lightning on transmission lines both in the field and in the laboratory. It is the purpose of this paper to coordinate this work with a view of determining the various types and order of magnitude of predatory voltages to which transmission lines are subject. No claim is made for exact results. If it were possible to obtain such results, they could apply only to specific cases. A knowledge of the general types of disturbances and their order of magnitude should be of great value in determining the best means of providing against them. Failures of apparatus can be provided against in a number of ways, for instance, by excessive insulation; by less insulation but a design to prevent local high stresses; by prevention of high lightning voltages by placing the line under ground; by greatly limiting the possible voltage by a ground wire; by limiting the time of application of the high voltage by arresters; or by combinations of the above. Obviously, the matter of design and economics is also of importance in considering the problem of protection. The technical part of the discussion will not be limited to cloud lightning, but will cover other disturbances. Recent work of the author with his lightning generator and model transmission lines with and without ground wire will be included.