(1) Plug-in fuse
Often used at the end of lines with voltage levels of 380V and below, as short-circuit protection for distribution branches or electrical equipment.
(2) Spiral fuse
There is a fuse indicator on the upper end cap of the melt. Once the melt melts, the indicator pops up immediately and can be observed through the glass hole on the porcelain cap. It is often used in electrical control equipment of machine tools. Screw type fuse. The breaking current is large and can be used for short circuit protection in circuits with voltage levels of 500V and below and current levels of 200A and below.
(3) Closed fuse
Enclosed fuses are divided into two types: filled fuses and unfilled fuses, as shown in Figure 3 and Figure 4. Filled fuses generally use square porcelain tubes filled with quartz sand and melt. They have strong breaking capacity and are used in circuits with voltage levels below 500V and current levels below 1KA. The filler-free sealed fuse packs the melt into a sealed cylinder and has a slightly smaller breaking capacity. It is used in power grids or distribution equipment below 500V and below 600A.
(4) Quick fuse
It is mainly used for short-circuit protection of semiconductor rectifier components or rectifier devices. Because the overload capacity of semiconductor components is very low. It can only withstand a large overload current in a very short time, so the short circuit protection is required to have the ability to blow quickly. The structure of the quick-acting fuse is basically the same as that of the filled sealed fuse, but the melt material and shape are different. It is a variable-section melt with a V-shaped deep groove punched from a silver sheet.
(5) Resettable fuse
Using metallic sodium as the melt, it has high conductivity at room temperature. When a short-circuit fault occurs in the circuit, the short-circuit current generates high temperature, causing the sodium to quickly vaporize, and the vaporized sodium presents a high-resistance state, thereby limiting the short-circuit current. When the short-circuit current disappears and the temperature drops, metallic sodium returns to its original good conductive properties. Resettable fuses can only limit short-circuit current and cannot actually break the circuit. The advantage is that there is no need to replace the melt and it can be reused.
When working, the fuse is connected in series in the protected circuit. When a short circuit or severe overload occurs in the circuit, the fuse link in the fuse will automatically blow to protect the circuit. The most common one is a fuse.
