Multi-Conductor Cable Modeling with Inclusion of Measured Coaxial Wave Propagation Characteristics

The prediction of voltage stresses in transformer and machine windings requires the ability to calculate pulse propagation effects on the feeding cable with sufficient accuracy. The use of commonly available cable models in electromagnetic transient (EMT) programs can lead to voltage wave fronts with too weak damping at very high frequencies. This work shows a method for improving the accuracy of such models by usage of measured coaxial mode propagation characteristics. The information is introduced into a wide-band multi-conductor cable model at high frequencies by a merging procedure, with only a minor impact on the non-coaxial modes of propagation. The application of the developed model is demonstrated for cases where the metallic sheaths are grounded at one end only, or are cross-bonded.