A model to predict current distributions in bundled cables for electric glass melters

Abstract

The authors present a model for predicting the current distribution in high current cables that are constructed from bundles of parallel conductors (strands). These cables are typically used in electric glass melters to interconnect the power transformers and the melter secondary bus installations. Due to the skin effect, the magnetic field forces inside the bundled cable will tend to drive the current toward the outermost strands. The model is developed by starting from the fundamentals of the skin effect phenomenon for solid conductors and extending the concept to bundled cables. It can be easily coded in a simple computer program that can be used for ampacity prediction and sizing of bundled cables used to supply large electric glass melters or other similar heavy-current applications. Results obtained using the model for a variety of cable-bundling configurations are presented for demonstration purposes. The results show that currents in the outermost layers of bundled cables can exceed those of the innermost layers by factors of four or more, depending on the total cable size. >