Fuse is the core device of circuit protection. It can be divided into many types according to the structure, purpose and performance differences. The following are the main classifications and characteristics:
1. Classification by structure
Plug-in fuses
Commonly used at the end of lines with voltage levels of 380V and below as short-circuit protection for distribution branches or electrical equipment.
Advantages: simple structure and convenient replacement; Disadvantages: limited breaking capacity.
Typical applications: lighting circuits and small-capacity motor protection.
Spiral fuses
Quartz sand is filled around the fuse, and the arc is quickly extinguished after spraying into the sand gap, with strong breaking capacity.
Rated current 5~200A, suitable for branch circuits with large short-circuit current or flammable environments.
Structural features: with fuse indicator, the status can be observed through the porcelain cap.
Enclosed fuse
It is divided into two types: Filled (square porcelain tube + quartz sand) and Unfilled (sealed cylinder):
The filled type has a stronger breaking capacity and is used for circuits below 500V and 1kA.
The unfilled type is suitable for distribution equipment below 600A.
2. Classification by function and use
Fast fuse
Designed for semiconductor components (such as thyristors), it has an extremely fast response speed and uses a silver V-shaped deep groove melt or solder joint structure.
Subtypes include cylindrical, screw cover, surface mount, etc., suitable for industrial equipment or PCB protection.
Self-resetting fuse
Using metallic sodium as the melt, it vaporizes to form a high resistance state to limit current when short-circuited, and automatically restores conductivity after the fault is cleared.
Advantages: reusable; Disadvantages: limited current but not completely disconnecting the circuit.
3. Other special types
High-voltage current limiting fuse: used in 3.6~12KV systems to protect transformers, capacitors and other equipment.
High-voltage drop-out fuse: Outdoor distribution transformer protection, with both isolation and short-circuit protection functions.