The role and working principle of the fuse

A fuse is also called a current fuse, and the IEC127 standard defines it as a "fuse-link". It mainly plays the role of overload protection. If the fuse is properly placed in the circuit, the fuse will cut off the current when the current abnormally rises to a certain height and heat, thus protecting the safe operation of the circuit.

1. What material is the fuse
 

The fuse is lead-antimony alloy wire. The material of the fuse must have special properties, because the function of the fuse is to block the current in time when danger occurs, thereby protecting the electrical appliance. Therefore, the material of the fuse must be a metal material with a low melting point.

The main component of lead-antimony alloy wire is aluminum, which has a low melting point and good corrosion resistance. At the same time, the magnesium element increases the hardness of the alloy wire, so it is an excellent material for making fuses. Many appliances in the family, such as rice cookers, electric pans, electric kettles and other household appliances, use fuses made of this material.

 

What material is a fuse

(The picture comes from the Internet)

 

2. The role and working principle of the fuse
 

The role of the fuse: When the current abnormally rises to a certain height and heat, the fuse will fuse and cut off the current, thereby protecting the safe operation of the circuit.

 

The working principle of the fuse: When the current flows through the conductor, the conductor will heat up due to the existence of a certain resistance in the conductor. And the calorific value follows this formula: Q=I2RT; where Q is the calorific value, 0.24 is a constant, I is the current flowing through the conductor, R is the resistance of the conductor, and T is the time for the current to flow through the conductor; according to this formula we It is not difficult to see the simple working principle of the fuse.

 

When the material and shape of the fuse are determined, its resistance R is relatively determined (if its temperature coefficient of resistance is not considered). It heats up when current flows through it, and it heats up over time. The size of the current and resistance determines the rate of heat generation. The structure of the fuse and its installation condition determine the rate of heat dissipation. If the rate of heat generation is less than the rate of heat dissipation, the fuse will not blow. If the rate of heat generation is equal to the rate of heat dissipation, it will not fuse for a long time. When heat is generated faster than it is dissipated, more and more heat is generated. And because it has a certain specific heat and quality, the increase in its heat is reflected in the increase in temperature. When the temperature rises above the melting point of the fuse, the fuse will fuse. This is how fuses work.

 

The role and working principle of the fuse

(The picture comes from the Internet)

 

3. Types and names of fuses
 

1. According to the scope of use, it can be divided into: power fuses, machine tool fuses, electrical instrument fuses (electronic fuses), and automotive fuses.

2. According to the volume, it can be divided into: large, medium, small and micro.

3. According to the rated voltage, it can be divided into: high voltage fuse, low voltage fuse and safety voltage fuse.

4. According to the breaking capacity, it can be divided into: high and low breaking capacity fuses.

5. According to the shape, it can be divided into: flat head tubular fuse (can be divided into internal welding fuse and external welding fuse), pointed tubular fuse, guillotine fuse, screw fuse, blade fuse, flat fuse, wrap Wrapped fuses, chip fuses.

6. According to the fusing speed, it can be divided into: ultra-slow fuse (generally represented by TT), slow fuse (generally represented by T), medium-speed fuse (generally represented by M), fast fuse (generally represented by F) , Very fast fuse (generally indicated by FF).

7. According to the standard, it can be divided into: European fuse, American fuse, Japanese fuse.

8. According to the type, it can be divided into: current fuse (chip fuse, miniature fuse, insert fuse, tubular fuse), temperature fuse (RH [square type], RP [resistance type], RY [metal shell]), Resettable fuses (inserts, laminations, patches).

9. According to the size, it can be divided into: SMD type 0603, 0805, 1206, 1210, 1812, 2016, 2920; non-SMD type Φ2.4×7, Φ3×7, Φ3.6×10, Φ4.5×15 , Φ5.0×20, Φ5.16×20, Φ6×25, Φ6×30, Φ6×32, Φ8.5×8, Φ8.5×8×4, Φ10×38, Φ14×51.

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