Current Source for Testing Long Line EMP Surge Arrestors

A 1.4-mH energy storage inductor is used with explosively actuated circuit breakers to simulate SREMP current injection into powerlines for testing prospective surge arrestors. By use of inductive energy storage, current through the surge arrestor is maintained in spite of device impedance changes. The energy storage inductor is energized by a self-excited homopolar generator. Current levels of up to 65 kA, corresponding to a stored energy of 3 MJ, are obtained by selecting initial generator speed. Discharge of this inductor into a surge arrestor results in a decaying current pulse with a duration determined by the L/R time constant of the circuit. For a surge arrestor resistance of 0.1 Ω, the resulting pulse duration is > 10 ms. With addition of a pulse transformer this pulse generator can deliver 10-kA currents for periods >100 ms.