An assessment of the survivability and performance of the at&t 5ESSTM, switch in a simulated HEMP environment

At the request of the National Communications System, AT&T recently conducted an EMP assessment of the 5ESS^{TM Switch. Its purpose was to firmly establish the ability of the 5ESS Switch to physically survive EMP, and to study its ability to continue operating without operator intervention following one or more EMP events. The assessment was based on four months of experimental testing of a small, operational 5ESS Switching Office under the EMP simulators at the Air Force Weapons Laboratory. While fully powered and carrying simulated call traffic, the switch was exposed to 531 electromagnetic pulses between 5 kV/m and 80 kV/m. This study showed that, with relatively minor modifications (now incorporated in production models), the 5ESS switch can physically survive EMP exposure and continue to operate. A significant fraction of calls set up before the pulse are often dropped, and the ability of the switch to process calls afterwards is usually degraded. However, complete switch restoration is always possible with the assistance of an operator.}