The strength of the quick fuse housing largely determines the breaking capacity of the maximum fault current. Secondly, the shape of the metal fuse inside the fast fuse, the ability and heat of the filler to absorb metal vapor, and the electric power of the fuse link all affect the breaking capacity. The fast fuse with insufficient breaking capacity will continue to ignite until it explodes, and in serious cases will cause AC and DC short circuit.
In addition, the dispersion of product manufacturing is also one of the factors that affect the breaking capacity. The problem that is easy to ignore is the power factor of the line in case of short circuit fault. The arc energy generated when the fast fuse is broken has a great relationship with the inductive reactance of the circuit. When the power factor of the line is cos φ＜ At 0.2, there is a special high requirement for breaking capacity.
When the fast fuse breaks, the energy Wo=Wa+Wr+W1, where: Wa - arc energy; Wr -- resistance energy consumption; W1 -- Line inductance releases energy.
When the breaking capacity meets the requirements of "rectifier", it should also be noted that the peak value of the arc voltage at the breaking moment (referred to as "transient recovery voltage" in the standard) should not be too high, and the fast fuse should be limited during manufacturing to make it lower than the maximum value that the semiconductor device can withstand, otherwise the semiconductor device will be damaged. Therefore, the fuse with the shortest breaking time is not necessarily the most suitable.
When the fast fuse is used in the DC circuit, there is no voltage zero-crossing during the DC breaking process, which is a harsh condition for the reliable breaking of the fast fuse. Generally, if the fast fuse is used in the DC circuit, only 60% of the rated voltage of the fast fuse can be used. It is better to use the DC fast fuse.
