Fast Fuse
May 13, 2022
Fast fuse is a type of fuse, which is mainly used for short-circuit protection of semiconductor rectifier components or rectifier devices. Due to the low overload capacity of semiconductor components. It can only withstand a large overload current in a very short period of time, so the short-circuit protection is required to have the ability to quickly fuse. The structure of the fast fuse is basically the same as that of the enclosed fuse with filler, but the melt material and shape are different. It is a variable-section melt with a V-shaped deep groove punched by a silver sheet.
In addition to a metal wire with a certain shape, the fuse of the quick-acting fuse will also have a solder joint of a certain material on it, the purpose of which is to make the fuse disconnect quickly under overload conditions.
Fast fuse is a type of fuse, which is mainly used for short-circuit protection of semiconductor rectifier components or rectifier devices. Due to the low overload capacity of semiconductor components. It can only withstand a large overload current in a very short period of time, so the short-circuit protection is required to have the ability to quickly fuse. The structure of the fast fuse is basically the same as that of the enclosed fuse with filler, but the melt material and shape are different. It is a variable-section melt with a V-shaped deep groove punched by a silver sheet.
In addition to a metal wire with a certain shape, the fuse of the quick-acting fuse will also have a solder joint of a certain material on it, the purpose of which is to make the fuse disconnect quickly under overload conditions.
Fast fuses highlight "fast", which means high sensitivity. When the circuit current is overloaded, the fuse will heat up quickly under the action of the solder joints, and the fuse will be quickly disconnected. A good fast fuse has a high efficiency and is mainly used for To protect thyristor and some electronic power components.
Structure of fast fuse:
The fuse consists of six parts: magnetic shell, conductive plate, melt, quartz sand, arc extinguishing agent and indicator. The material of the melt is pure silver, and the shape is a rectangular sheet with a round hole and a narrow neck.
Characteristics of fast fuses:
Inverse time current protection feature. The fuse has inverse time delay characteristics, that is, when the overload current is small, the fusing time is long; when the overload current is large, the fusing time is short. Therefore, within a certain overload current and overload time range, the fuse will not be blown and can be used continuously. Fuses have various fusing characteristic curves, which can be applied to the needs of different types of protection objects
Current limiting characteristics:
Because the melt of the fast fuse is a rectangular sheet with a series of circular holes and narrow necks, and is filled with quartz sand arc extinguishing medium. The cross-sectional area at the narrow neck of the circular hole is small, and the heat capacity is small. When a short-circuit fault occurs, when the fault current has not reached the expected short-circuit current, it is fused, and the arc is divided into many small sections by quartz sand. In this way, the increase of the short-circuit current is limited and the extinguishing of the arc is accelerated.
Strong breaking ability
When a short-circuit fault occurs, the narrow neck of the circular hole is first fused, and the arc is divided into many small sections by the quartz sand, and the arc is quickly extinguished. Since the quartz sand is insulating, after the arc is extinguished, the fuse immediately becomes an insulator, breaking the circuit. Therefore, the fast fuse has a strong breaking capacity, which can be as high as 50kA.
When a short-circuit fault occurs in a circuit with a small impact energy that the load equipment bears, the impact energy that the load equipment bears is:
W=IRt In the formula, I-short-circuit current; R-circuit resistance; t-time from short-circuit fault occurrence to circuit being cut off. The fast fuse has a short breaking time and has a good current limiting effect, so the impact energy of the load equipment is small.
