1. Under normal circumstances, fuses play a connecting role in the circuit.
2. Under abnormal (overload) conditions, the fuse serves as a safety protection component in the circuit, which can safely cut off and protect the circuit through its own fusing.
2、 The working principle of a fuse:
When a fuse is energized, the heat converted from electrical energy causes the temperature of the melt to rise. When normal working current or allowable overload current passes through, the heat generated is radiated to the surrounding environment through the melt or shell, and the heat dissipated through convection, conduction, and other means gradually reaches a balance with the heat generated. If the generated heat is greater than the dissipated heat, the excess heat gradually accumulates on the melt, causing the temperature of the melt to rise; When the temperature reaches or exceeds the melting point of the melt, it will cause the melt to melt, fuse, and cut off the current, playing a role in safety protection of the circuit.
3、 Classification of fuses:
1. Divided into: φ 2 φ 3 φ 4 φ 5 φ 6 and others.
2. According to the fuse characteristics, it is divided into fast fuse type, medium delay fuse type, and delay fuse type. (It can also be divided into express and strong delay).
3. According to the breaking capacity, it can be divided into low breaking type, high breaking type (and can also be divided into enhanced breaking type).
4. According to safety standards (or usage regions), it can be divided into UL/CSA (North America) specifications, IEC (China, Europe, etc.) specifications, MIT/KTL (Japan/Korea) specifications, etc.
5. Other classifications.
4、 Characteristics and terminology of fuses:
1. Rated current: The nominal working current of the fuse tube (the maximum current that a fuse can maintain normal operation for a long time under normal conditions).
2. Rated voltage: The nominal working voltage of a fuse (the maximum voltage that the fuse can safely withstand at the moment of disconnection). When selecting a fuse, the rated voltage of the selected fuse should be greater than the input voltage of the protected circuit.
3. Breaking capacity: When a large overload current (such as a strong short circuit) occurs in a circuit, the fuse can safely cut off (break) the maximum current of the circuit. It is an important safety indicator for fuses. Safe breaking refers to the phenomenon of avoiding splashing, burning, explosion, and other hazards to surrounding components, components, and even personal safety in the breaking circuit.
4. Overload capacity (carrying capacity): The maximum overload current that a fuse can maintain for a specified period of time. When the current flowing through the fuse exceeds the rated current, after a period of time, the melt temperature will
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