ESD Induced EM Field Coupling to Braided and Non-braided Shielded Cables

摘要

A Transmission Line coupling model is developed for determining the transient currents and voltages induced within braided and non-braided shielded cables by an impinging transient pulse generated by an Electrostatic Discharge (ESD) event. The Transmission Line theory is applied to establish the differential equations describing the behaviour of the cables in the presence of a uniform plane travelling wave. At first, induced sheath currents are calculated taking into account coupling in shielded cables. Then internal voltages and currents are computed via the surface transfer impedance of cable shields for single layer outer conductors. The penetrating field from an ESD event may induce unwanted transient voltage in the centre conductor of the cable. The calculation of the induced voltage in the centre conductor of the coaxial cable requires the details of the ESD waveform, the induced sheath current and the surface transfer impedance. The modelling of the shielded cable exposed to the free space-radiating field due to IEC 61000-4-2 ESD current waveform is carried out to compute the surface transfer impedance, sheath current, induced voltage and current in the centre conductor.