Effect of core-clamp pressure on the sound level emitted by the cores of dry-type distribution transformers

Analytical experimental results are presented concerning the correlation between the pressure to which the core of a dry-type distribution transformer is clamped and the intensity of the magnetic sound emanating from it. The authors elaborate on additional relationships intrinsic to this phenomenon, such as sound versus frequency, weight, and flux density. Various clamp constructions used in the experimental measurements are shown. Guidelines for choosing the proper clamping arrangements are discussed. Although these phenomena apply to any magnetic core, the present work is restricted to cores of dry-type distribution transformers from 15 to 2500 kVA