Response of long lines to nuclear high-altitude electromagnetic pulse (HEMP)

During high-altitude nuclear testing in 1962 over Kazakhstan, several system effects were noted due to the high-altitude electromagnetic pulse (HEMP). In particular a 500-km-long aerial communications line experienced a failure due to the damage of its protective devices. This failure is examined in detail beginning with the calculation of the incident HEMP environments, including those from the early- and late-time portions of the HEMP. In addition, the currents and voltages induced on the line are computed and the measured electrical characteristics of the protection devices are presented. With this information it is possible to determine which portions of the HEMP environment were responsible for particular protection failures. The paper concludes with recommendations for further work required to understand the best ways to protect power lines from HEMP in the future.