Proximity Effect in Solid and Hollow Round Conductors

A new formula is developed for the proximity effect in single-phase systems of solid and hollow round conductors to replace the two formulae developed by the author and published in 1935 and 1936 respectively. Two independent formulae for the cases of solid and hollow conductors are replaced by a single formula for hollow conductors, including the solid conductor as a particular case. The new formula is simpler and can be evaluated numerically in a shorter time. It is more accurate and is valid for all possible values of the independent variables. The earlier solid-conductor formula failed for certain ranges of the independent variables. Improved formulae are also given for 3-phase systems. The discrepancies between values calculated by the new formulae and values obtained from experimental measurements are little, if any, greater than possible experimental errors.