Jean-Louis Gelet (1), Tadahiro Hayashi (2)
(1) MERSEN SB sas, Rue Vaucanson, 69720 Saint-Bonnet de Mure– France, jean.louis.gelet@mersen.com
(2) MERSEN JAPAN KK, Shinjuku Dai-ichi Seimei Bldg 3F P.o. Box 5059 2-7-1 Nishi-Shinjuku Shinjuku-ku, 163-0703 Tokyo, Japan
Abstract
Fuses-manufacturers carry out many tests in order to evaluate the life-duration of their products, but tests cannot match exactly actual conditions in the field. Then, they have to extrapolate test-results for estimating life-duration in operation. MERSEN drew out a method based on determination of coefficients applied to the fuse-rating for withstanding the required life-duration.
But, fuses are often submitted to complex conducting-cycles, combining short and long periods, with more or less high current-values, even with off-times. The common and simple approach is to calculate coefficients corresponding to each stress and to combine them by multiplication.
This can lead to excessive restriction of the current in the fuse, or reversely to large fuse-ratings, increasing I²t and reducing the short-circuit-protection. In this paper, MERSEN will propose an improved method using accumulative-effect approach. This method will help the application-engineers to better choose the fuse and improve the quality of the equipments.
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