Nanocrystalline magnetic aging study
Résumé
Increasing concerns of energy crisis and demand for higher efficiency In transformers, demand of distribution transformers based on amorphous alloys is Increased, The number of makers of amorphous alloy based transformers and Fe-based amorphous strips (AM-strip) is also Increasing. However there Is no international standard for AM-strip which supports smooth trade transactions and IEC/TC68 has made efforts to establish material and measurement standards for AM·strip. Since grading of AM-strip by specific Iron loss value will be introduced in the standard, it is necessary to establish the measurement method of specific iron loss. In previous papers, we pointed out that it is essential to measure specific iron loss of not a toroidal core but a single sheet since AM-strip is stress sensitive due to larger magnetostriction. Also we developed amorphous single sheet tester (AM·SST) using Mn-Zn ferrite yoke to measure about 1/10 of specific iron loss in AM-strip than that of GO steel sheet and confirmed that relative standard deviation is within 3% which Is required to distinguish the grades. In this paper, we report followings; Firstly, results of 1st International round robin test, secondIv AM-SST utilizing 220nm wide Mn·Zn ferrite yoke in accordance with lEC draft to measure as-cast wide AM-strips (142 mm-213 mm) and the measured results. Also the calibration method of area-turn of H-coil with magnetizing winding and improvement of S/N ratio of signal from H-coil are reported,