Effect of magnetic pickups on the input transformers of measuring devices

Summary The asymmetry coefficient for all types of transformers depends on the core permeability, which in turn depends on the ratio ofl _av/s or D_av/s. In order to reduce core permeability, it is necessary to select toroidal cores with a small diameter and a large cross section, and provide laminas of O-shaped and shell-type cores with a shape to make these cores short and large in cross section.Under actual operating conditions, transformers with toroidal cores provide a higher immunity from noise. For the same designs, sizes, and relative parameter dispersions, the transformers with toroidal and O-shaped cores have a ratio of _max equal to 1.6. In shell-type transformers it is imperative to take into account the polarity of their windings on which the transformer's noise stability depends to a great extent.