During high-altitude nuclear testing in 1962 over Kazakhstan, several syste
m effects were noted due to the high-altitude electromagnetic pulse (HEMP),
In particular a 500-km-long aerial communications line experienced a failu
re due to the damage of its protective devices. In this paper, 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 compu
ted and the measured electrical characteristics of the protection devices a
re presented. With this information it is possible to determine which porti
ons of the HEMP environment were responsible for particular protection fail
ures. The paper concludes with recommendations for further work required to
understand the best ways to protect power lines from HEMP in the future.