Revisiting the Determination of Busway Impedance Using First Principles

An approach using a combination of well-known circuit principles is used to convert the impedance matrix-determined for three-phase single lamination per phase busway-to industry-specified “average” impedance values as specified by the National Electrical Manufacturers Association. This paper details how this approach can be used to predict average busway impedance with reasonable accuracy, and therefore help in reducing the number of physical tests and related costs in the design process. Four cases are provided for validation purposes. The results show good correlation with published data.