An Electrical Surge Arrestor (ESA) Model for Electromagnetic Pulse Analysis

Electrical Surge Arrestors (ESA´s) have been used extensively for lightning and EMP protection. These components are characterized by (a) presenting an open circuit (high impedance) below the gap breakdown potential, (b) becoming a virtual short-circuit above the gap breakdown and (c) displaying a significantly higher level of apparent gap breakdown for very fast input voltage rise-times (dv/dt). This paper describes a mathematical model for a spark gap surge arrestor which has been used successfully to characterize ESA response to the following stimulus: 1. Below DC Gap Breakdown 2. At or above Gap Breakdown 3. At high apparent Gap Breakdown voltage as a function of increased rise-time 4. Damped Sinewave Input (below and at Gap Breakdown) 5. Exposed to prompt gamma radiation using a Flash X-Ray source and an electrical input