The physical state of laminated soft magnetic machine cores has high technical and economical relevance, in particular if advanced materials are involved, as in the case of transformer cores. Experimental analyses tend to be restricted to core surface regions due to the high expenditure of interior arrangements of sensors. Further, the latter cause inter-laminar spaces, as a reason of artefacts. The paper presents a completely novel sensor concept that avoids the above problems. A magnetic detection band of e.g. 1 m length consists of different kinds of sensors. They are arranged on a substrate foil by combined 2D/3D-printing, the total band thickness being below 100 [Formula: see text]m. Using the ends as handles, the band is located through the core. Electric connection sockets to electronics remain outside, thus avoiding increased inter-laminar spacing. They also allow for later failure diagnostics, by permanently arranged bands. Sensors concern local distributions of magnetic flux, losses, temperature, strains and vibrations. Manufacturing is aimed on versatile low-cost products. This paper describes procedures that are focused on flux sensors, in particular for in-plane flux that represents the most complex sensor type. For the first time, it enables interior measurements in non-destructive ways.

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Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the optimization of core performances aiming at a reduction of core losses and of audible noise. Conventional sensors for off-plane flux measurements tend to be either of high thickness, influencing the measured fluxes significantly, or require laborious preparations. In the current work, thin novel detector bands for effective and simple off-plane flux detections in laminated machine cores were manufactured. They are printed in an automatic way by an in-house developed 3D/2D assembler. The latter enables a unique combination of conductive and non-conductive materials. The detector bands were effectively tested in the interior of a two-package, three-phase model transformer core. They proved to be mechanically resilient, even for strong clamping of the core.

In the recent years, the reducing of audible noise of laminated machine cores has become great importance, due to high relevance given to environmental awareness. The strain caused by magnetostriction and magnetostatic forces is recognized as one of the main sources of noise. Especially for transformers, strain in the core interior tends to be different from that on the surface, due to differences of clamping, variation of in-plane fluxes and pronounced off-plane (normal) fluxes. For the first time, local measurements of strain in the core interior are presented by means of a novel printed detector band. First results tend to be very promising, exhibiting very high sensitivity and resolution. So far, the relevance of measurements is restricted to comparisons of different core regions.