The open fuse has a simple structure

Fuses can be divided into high-voltage fuses and low-voltage fuses according to the voltage used. According to the protection object, it can be divided into fuses for protecting transformers and general electrical equipment, fuses for protecting voltage transformers, fuses for protecting power capacitors, fuses for protecting semiconductor components, fuses for protecting motors and fuses for protecting household appliances. fuses, etc. According to the structure, it can be divided into open type, semi-closed type, tubular type and spray type fuse.

The open fuse has a simple structure, the melt is completely exposed to the air, and is supported by a porcelain column without a support, which is suitable for low-voltage outdoor use. When the current is interrupted, a large sound and light is generated in the atmosphere.

The melt of the semi-enclosed fuse is installed on a porcelain frame and inserted into a porcelain box with metal sockets at both ends, which is suitable for low-voltage indoor use. When breaking the current, the generated sound and light are blocked by the porcelain box.

The melt of the tubular fuse is contained in the fuse body. Then plug it into the stand or connect it directly to the circuit for use. The fuse link is a completely sealed insulating tube with metal caps or contact blades at both ends. If the insulating tube of this fuse is filled with quartz sand, it will have a current limiting effect when breaking the current, which can greatly improve the breaking capacity, so it is also called a high breaking capacity fuse. If the tube is evacuated, it is called a vacuum fuse. If the tube is filled with SF6 gas, it is called SF6 fuse, and its purpose is to improve the arc extinguishing performance. Since quartz sand, vacuum and SF6 gas have good insulating properties, this fuse is not only suitable for low voltage but also high voltage.

Jet fuses contain the melt in an insulating tube made of solid gas-generating material. The solid gas generating material can be made of electrical anti-white cardboard or plexiglass material. When the short-circuit current passes through the melt, the melt is immediately fused to produce an arc, and the high-temperature arc causes the solid gas-producing material to rapidly decompose to generate a large amount of high-pressure gas, so that the ionized gas is ejected at both ends of the tube with an arc, emitting great sound and light, And when the AC current crosses zero, the arc is extinguished and the current is interrupted. The insulating tube is usually mounted on an insulating bracket to form the whole of the fuse. Sometimes the upper end of the insulating tube is made movable, and after breaking the current, it is disconnected and dropped. This type of jet fuse is commonly known as a drop fuse. Generally suitable for outdoor occasions where the voltage is higher than 6 kV.

In addition, fuses can be divided into general-purpose fuses, backup fuses and full-range fuses according to the breaking current range. The breaking current range of general-purpose fuses refers to the range from the overload current greater than 1.6 to 2 times the rated current to the maximum breaking current. Such fuses are mainly used to protect power transformers and general electrical equipment. The breaking current range of the backup fuse refers to the range from the overload current greater than 4 to 7 times the rated current to the maximum breaking current. This fuse is often used in series with the contactor. When the overload current is less than 4 to 7 times the rated current, the contactor is used to realize the breaking protection. Mainly used to protect the motor.