Study on Cable Coupling Effects of Lightning Strikes on a Metal Mast

Abstract

Aiming at the problem of coupling response characteristics of internal cables when metal masts are struck by lightning, a lightning induction coupling test platform for the cable system inside the masts was built, and the induced voltage of coaxial cables, two-core single-shielded cables, and multi-core double-shielded cables were measured under four kinds of terminal load characteristics (open circuit at both ends of core wire, the end of the core wire near from the ground is connected to the load, the end of the core wire far from the ground is connected to the load and both ends of the core wire are connected to the load). From the perspective of time domain and frequency domain, the influence of load characteristics on induced voltage is analyzed. The results show that under the function of simulated lightning currents, the induced voltage of three cables all reaches the maximum value when the far-ground end of wire is grounded by load; the main frequency band of the induced voltage is greater than the lightning current when the near-ground terminal is grounded by load, while the two are similar under other load characteristics; grounding the inner shield can reduce the peak value of the induced voltage, its effect depends on the terminal load characteristics, but does not affect the main frequency band of the frequency response. This paper reveals the influence of terminal load characteristics on cable coupling induced voltage when lightning strikes the metal mast of a ship, and provides basic data support for the subsequent calculation of coupling effect.