What is the working principle of the fuse?

I still remember that I studied electronics and electrical majors when I was studying. When I went home on vacation every semester, I was asked to repair TV by the people in my neighborhood. At that time, I used black and white TVs, and the voltage was unstable at that time. The most damaged is the fuse.

At that time, the fuse was an ordinary glass tube fuse. It is not very convenient to buy a fuse in the countryside. Sometimes, you can directly connect the circuit with an iron piece or wire to act as a fuse (I believe many people have done this), and it works fine. It is used, but it is very unsafe to use. Sometimes it will damage other parts of the TV. Since then, it has been impressed by this transparent glass tube fuse.

A fuse is also called a fuse. It is defined as a "fuse" in international standards. It is an electrical component installed in a circuit to ensure the safe operation of the circuit.

Electronic products are all-encompassing, and these products that require electricity must be equipped with the same small components that are responsible for safety. Fuses not only have fuses on 3C products, but also must be installed on ordinary cars or electric cars.

Now as products are getting smaller and smaller, more and more integrated, the shape and size of the fuse are also very different from traditional fuses. For example, the fuse of a mobile phone must conform to the trend of fast charging, and it must withstand a momentary large current. To achieve its protection function, the requirements of fuses are getting higher and higher.

The glass fuse fuse that we usually see is not a single material. It is an alloy made of lead, antimony, tin. These metals are added for the purpose of achieving a low melting point. Both ends are copper caps, which are conductive The performance will be better, the surface of the copper cap is nickel plated.

The shape of the fuse is the earliest used wire fuse, which is directly fixed with screws on both ends, and is used on the old-style electric brake.

The chip fuse is composed of a plastic sheet and two metal sheets. It is commonly used in automobiles, and the glass tube is commonly used in electronic products.

Cylindrical fuses will directly solder the pins on both ends to the circuit board. Square fuses have the characteristics of insulation and space saving, and are commonly used in electronic products such as computers.

The function of the fuse is that when the circuit is faulty or abnormal, the current is continuously increased, and the increased current may damage the components, or it may burn the circuit or even cause a fire.

If a fuse is installed in the circuit, it will blow the fuse to cut off the current when the current rises abnormally to a certain height, thus protecting the electrical appliance.

The fuse was born in the 1880s. Edison invented a fuse equivalent to a safety valve in the circuit and applied for a patent. At that time, the fuse was invented to protect the incandescent lamp, because the incandescent lamp was very expensive at the time when it was just invented. .

With the development of society and the increasing number of electrical appliances, the fuse industry has also developed rapidly. The fuse industry in China started late, and it was not until the localization of television sets in the 1970s that the development of fuses in China was promoted.

The working principle of the fuse is that when the current passes through the conductor, the conductor will heat due to the resistance of the conductor. After the material and shape of the fuse are determined, the resistance is determined. When the current flows through it, it will It will generate heat, and its heat will increase with time. The size of current and resistance determine the speed of heat generation. The structure of the fuse and its installation status determine the speed of heat consumption. At speed, 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. If the rate of heat generation is greater than the rate of heat loss, then the amount of heat generated will be more and more, and the increase in heat will be It will cause the temperature to rise. When the temperature rises above the melting point of the fuse, the fuse will blow.

In the manufacture of common glass tube fuses, the silica material is first drawn into a transparent glass tube with a diameter of 5 mm at high temperature, and then cut into a length of 30 mm. When the sharp edge of the glass tube scratches the fuse.

An alloy fuse is placed in the glass tube, and the printed top and bottom covers are welded to the fuse with high frequency.

Finally, the machine automatically detects the fuse, ejects the unqualified fuse, and packs the qualified fuse.

Some people may wonder why the common fuse is installed in the glass tube. First, the glass tube is insulated and not easy to ignite, ensuring that the fuse is the only conductive connection intermediary at both ends. The cheap price of the glass tube is also the reason for using it. In addition, the glass tube can see whether the internal fuse is blown, it is easier to judge the quality of the fuse, and the glass tube is not vacuum.

With the development of technology, more types of fuses have appeared, such as recoverable fuses. This fuse will automatically deform when the temperature exceeds a certain safe temperature, resulting in power failure. After the temperature is restored, it can be automatically energized to work normally. Manual intervention.

There is also a temperature fuse. This fuse will automatically blow when the temperature of the appliance reaches a certain safe temperature, cut off the power, and avoid the occurrence of fire, such as commonly used electric cookers, coffee machines, etc., but the temperature fuse does not have the current protection of ordinary fuses effect.

Ordinary fuses are simple in structure and relatively easy to manufacture. They can produce dozens per minute. Current electronic products require higher and higher fuses. In order to meet these requirements, fuses must be “light, thin, and short”. The fuse market of large electric power will have higher requirements, and small fuses play an important role in various electronic appliances.