When Is It Necessary To Use Fuses To Calculate The Short-circuit Current Of Newly Built Lines In Low-voltage Power Distribution Design?

When the system impedance is low, the power supply capacity is large, and the conductors are short or the transformer capacity is large, the fault current may reach thousands of amperes or even higher. In such cases, directly selecting drop out fuse protection without calculating the short-circuit current may result in the fuse's breaking capacity being lower than the actual fault current. Risks include the fuse failing to trip, equipment damage, cable overheating, or fire.

For projects with long feeders, high cable impedance, or high system impedance, and sensitive load-side equipment, short-circuit current calculations are also necessary. Although the short-circuit current may be lower due to impedance attenuation, it is still necessary to confirm whether the fuse can operate normally under the maximum possible short-circuit current to avoid the potential risk of "insufficient breaking capacity."