Low-impedance cable for parallel-connected surge protective devices

A coaxial low-impedance cable is described for power system surge protective device (SPD) wiring applications, The cable is designed to replace conventional wiring when parallel connecting any SPD which depends on the applied transient voltage to function. The cable is designed to minimize the transmission loss (voltage drop) of lightning and switching transients from the point of protection to the SPD components. This is accomplished primarily by minimizing the cable inductance through a reduced coaxial aspect ratio (major to minor diameter). The resultant cable has a very low characteristic impedance (2-15 Ω). The suppression performance of an SPD installed with 10 AWG coaxial cables provides an improvement of a factor of 2-4 over that using conventional wiring. The cable design details are discussed along with surge suppression performance