Experimental and Numerical Analysis of Stray Field From Transformers

We present an assessment of a numerical methodology for evaluating stray fields from transformers by direct comparison with experimental results. The methodology can help to ensure compliance with the limits imposed by national and international laws and regulations on the levels of magnetic fields. We conducted validation experiments on a 1000-kVA cast-resin transformer. All measurements were performed in an anechoic room, in short-circuit conditions, along different directions in space. We compared two different numerical methods, based on linear and nonlinear 3-D finite-element methods, respectively, with the experimental results. Agreement with the measurements was very good. Numerical tools can be considered a valid alternative to measurements for the analysis of the stray magnetic induction field and for the design of shielded devices.