Quick-acting fuse links specified in IEC 127 part 2, standard sheet II, have power dissipations which do not exceed 2.5 W (see table 4.3). As an example, let us assume that the rated accepted power of a fuse holder is 2.5 W.
Basically, this means that the rated current is not a fixed value. This rated accepted power determines the rated current.
For example, it means that at a power dissipation of 4 W (by a fuse link placed in the fuse holder) temperatures of the fuse holder should not exceed certain limit values as specified in the standard. The rated accepted power is, according to IEC 257, "A stated value of power dissipation (of a fuse link) which a fuse-base or fuse holder can accept under prescribed conditions of use and behavior." Rated values of accepted power are 1.6 W, 2.5 W or 4 W. According to IEC 257, the rated current is determined by the rated accepted power of a fuse holder. Considerable differences exist between the IEC and the UL standards regarding the rated current of a fuse holder. In the following, some of the most important differences between the two standards will be indicated.įrom an application point of view, a fuse holder is characterized by the features discussed in the previous section by its rated values for voltage, current, and accepted power. In the case of fuse links, compliance with the UL-standard does not usually mean that the fuse holder under consideration meets IEC-requirements and vice versa. 2 to this publication dated January 1989.īoth standards show considerable differences.
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