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H. Pfützner, K. Futschik, P. Hamberger, M. Aigner:
"Concept for More Correct Iron Loss Measurements Considering Path Length Dynamics";
Talk: International Workshop on 1&2 Dimensional Magnetic Measurement and Testing, Wien, Österreich; 2012-09-03 - 2012-09-06; in: "Short Paper Proceedings", (2012), ISBN: 3-902-105-03-8; 24 - 25.

As well known, iron losses p can be determined through the time integral over the field H and the derivative of the induction B. While Japanese methods determine H in a direct way, most labs prefer single sheet testers (SSTs) or Epstein testers (ETs) where H of the quasi-homogenic magnetized sample section is assumed to be proportional to the magnetization current i. However, this proportionality does not exist due to the periphery - the yoke of SST and the corners of ET, respectively. Usually, the periphery is considered through an effective magnetic path length I_{M} as a function of the peak induction B_{PEAK}. However, in special for grain oriented materials, the periphery represents a 3-D phenomenon which shows dynamic modifications in a periodical way. As a new approach, this is considered through a path length function Λ#(t) which is determined for each grade of material in a calibration process by means of a tangential field coil. Implementation in the process of measurement is simple. However, the usual electro-dynamic wattmeter has to be replaced by numerical integration. More correct results are expected for both SST and ET.