Affiliations: [a] Institute EMCE, TU Wien, Vienna, Austria | [b] Transformers Linz, Siemens AG Österreich, Linz, Austria
Correspondence:
[*]
Corresponding author: Georgi Shilyashki, Institute EMCE, University of Technology Vienna, Gusshausstrasse 25/354, Vienna 1040, Austria. Tel.: +43 1 588 01 35151; E-mail:[email protected]
Abstract: For the development of new strategies for reduction of
energy losses and audible noise of transformer cores, the assessment of the
induction distribution is essential. The results confirm that the core
represents a strongly inhomogeneous 3-dimensional magnetization system. For
a full understanding of distributions, measurements in the core interior are
necessary. For the first time the paper presents detailed analyses of
induction distribution in a multi-package model core. Automatic measurements
were performed in 112 local positions within 3-phase, 3-limb transformer
core stacked from three packages of different width of grain oriented
material. As a completely novel approach, a soft magnetic Fe-pin (of 2.4 mm
diameter) with pick up coil was used as an a priori calibrated pin sensor.
25 measurement channels (of 3 mm diameter) were established through the
entire core. Z-profiles of the induction through the channels were
determined in an automatic way for a nominal induction of 1.7 T. They
confirm that the core represents a system that is magnetized in a strong
inhomogeneous way. Strong variations of the induction up to 10% were
observed not only for the in-plane direction, but also along the normal
direction (off-plane). Maximum induction values were detected in the widest
main package, minimum ones in the narrowest peripheral package. An exception
is the corner area where the inhomogeneity of B decreases, linked with a
balancing off-plane flux. The paper proposes a model for the flux
distribution through the three packages of the core.
Keywords: Magnetic sensors, induction distribution, transformer cores
