Numerical method in low voltage fuses design

The improvement of rupturing capacity and reliability of fuse-line is based on prediction of the interruption time – current characteristic. This coupled problem in calculation of transient current and temperature distribution in about 400 seconds (with extra careful investigation for the first 200 milliseconds) was solved by algorithms used for steady state conditions expended for a wide range of physical data and adopted for automatic step-by-step procedure. The method contains: (a) discretization of 3D fuse model by finite elements, (b) determination of momentary current as its flow distribution over fuse-link, (c) determination of momentary temperature as sub-volume heat distribution due to magnetic and thermal sources and cooling paths, (e) determination of pre-arcing time that corresponds to the melting temperature of fuse-link. Calculated t(i) was in good agreement with statistical measured result.