Andreas. I. Chrysochos

This work investigates the effectiveness of various state-of-the-art techniques for determining the parasitic inductance of surge protective devices across a wide frequency range. This is critical, as the intrinsic inductive characteristics of surge protective devices influence their maximum residual voltage, which directly affects their protection efficiency against fast-front transients with high current derivatives. To provide an innovative solution to the problem of parasitic inductance determination, the parasitic inductance of single-phase and three-phase DIN rail surge protective devices is estimated by replacing the voltage-limiting components with copper blocks. Three methods are employed to estimate the parasitic inductance: (i) Impedance spectroscopy measurements, (ii) impulse current tests, and (iii) finite element analysis simulations. The results are analyzed to evaluate the accuracy of the proposed methods and address key challenges encountered in determining the parasitic inductance. It is found that the parasitic inductance of the protection mode exhibiting the longer surge current path is up to 1.6 times greater than that of the shortest surge current path for the three-phase (3+1) surge protective device, and consequently the maximum residual voltage increases by ~10% when subjected to its nominal discharge current of 20 kA with an 8/20 μs waveform for the same protection modes.

Electromagnetic interference (EMI) between overhead lines (OHL) and nearby pipelines may cause high-induced voltages. Their computation is important for the safe and reliable operation of the pipeline and necessitates the accurate evaluation of earth conduction effects on the impedance and admittance parameters of all conductors. In this article, a detailed formulation of the impedance and admittance parameters of OHL/pipeline configurations is presented and new expressions for the calculation of the mutual impedance and admittance between the overhead conductors and the buried pipeline are introduced. The mutual parameters for an OHL/pipeline configuration are evaluated by the new formulas and compared with those derived from existing ones, the method of moments and the finite element method. The propagation characteristics are also calculated justifying the use of the mutual admittance, that is typically disregarded in power systems EMI calculations. Transient simulation results with the developed formulas are performed to evaluate the importance of the proposed approach on EMI studies.