Research on the design optimisation of cable armour for protection against NEMP

The authors show that the penetration of the pulse occurs mainly by transfer impedance. An iterative formula allows this impedance to be calculated for systems consisting of several layers having different characteristics: the limitations of the method reveal the impossibility of determining the effects of magnetic saturation. Results are given for single and double sheathing, with and without intermediate insulation and for 3-layer sheathing with an intermediate magnetic tape layer, also for copper, aluminium, soft iron, steel and lead sheathing material and conductors. (F.N.S.)