Studies in lightning protection on 4000 volt circuits

Investigations forming the basis of the paper have been carried on for a period of five years. They were made on a system which at present supplies service to 250,000 customers over some 3000 miles of circuit, through about 16,000 transformers. During the experiments a number of theories have been tried out in practise and the results of the experiments are given in some detail. At the beginning of 1915, three distinct types of arresters and three schemes of protection were in use. The conditions during the year 1915 and the records obtained from lightning storms during the year are set forth by means of a number of maps, drawings and tables. An analysis of the results is followed by a list of conclusions. The several methods of improving the lightning protection have together resulted in eliminating over 90 per cent of the troubles from lightning.