company news about Time of fuse-current characteristic curve

It is one of the most important basis for choosing a fuse. It determines whether the fuse can effectively protect the circuit. When the fault current occurs, the correct melting. The melting characteristics of each model fuse have [Y1] each time current curve. The horizontal coordinates of the curve are current, and the vertical coordinates are the time of melting. In the process of selection, this curve is used as a reference, and the key points in the curve are used as the basis. The choice of key points is different and different according to the category of fuse certification. UL certification fuses generally choose 110%IN, 135%in, 200%in key points, IEC fuses generally choose 135%in, 210%in, 275%in, etc. Key points, the relationship between melting time and key points can be referred to the introduction in 3.7. When choosing a fuse, you need to determine the time when the protected fault current can safely exist in the circuit.

Example: A fast fuse is certified in accordance with the IEC standard, with a rated current of 5A. When a certain failure appears on the single board, the fault current flowing through the fuse is 10A, which is 200%in. According to the time current characteristic curve of the fuse, in the case of 200%IN, the fuse may work for 30 minutes before melting. At this time, the fuse is short, so that the measured sheet board worked at this fault current for 30 minutes. As a result, a fire occurred, indicating that the selection of this fuse was inappropriate. Before the fuse of the fuse began, the protected device was unsafe and did not achieve the purpose of protection.