Surge currents in protective devices

Lightning arresters are expected to protect equipment against damage and outage from lightning, and to have an economical life. In order to accomplish these ends effectively, arresters should be able to discharge all surge currents whose probability of occurrence is such that the average life of the arresters will be in an economic balance with their cost. In this paper existing data have been assembled and analyzed in an effort to determine the magnitude of these impulses and the probable frequency of their occurrence.