Considerations when selecting fuses

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1. Tips for selecting fuses: Fuses are chosen primarily based on the load conditions and the magnitude of the circuit’s breaking current. For example, for the protection of lighting circuits or shunt motors with relatively small capacity, it is advisable to use RC1A series plug-in fuses or RM10 series fillerless sealed tube fuses ； For circuits with high short-circuit currents or in environments with flammable gases, it is advisable to use RL series spiral fuses with high breaking capacity, or RT (including NT) series filled-sealed tube fuses ； For protecting silicon rectifiers and thyristors, fast fuses should be used. 2. Principles to be followed when selecting fuses: 1) Determine the type of fuse based on the operating conditions. 2) When selecting the specifications of a fuse, the specifications of the fuse element should be determined first, and then the fuse specifications should be chosen based on that fuse element. 3) The protection characteristics of the fuse should match well with the overload characteristics of the protected equipment. 4) In a power distribution system, fuses at different levels should be compatible with each other; generally, the rated current of a fuse at a higher level should be 2 to 3 times greater than that of the fuse at a lower level. 5) For fuses used to protect motors, attention should be paid to the effect of the motor’s starting current; fuses are generally used only for short-circuit protection of motors, while thermal relays should be employed for overload protection. 6) The rated current of the fuse should be no less than the rated current of the fuse element ； The rated breaking capacity should be greater than the maximum short-circuit current that may occur in the circuit.