The working principle of fast fuses and high-speed fuses
Structure of fast fuse
Fast fuse, high-speed fuse consists of six parts: housing, contacts, melt, high silicon quartz sand, curing agent, and indicator. The material
of the melt is pure silver, with a rectangular thin sheet shape and circular holes.
GFEFUSE: Arc extinguishing principle of fast fuses
The melt of GFEFUSE brand fast fuse is made of pure silver. Due to the low resistivity and good stability of pure silver, the melt of the fast
fuse has a circular hole and narrow neck structure. When a short circuit fault occurs, the current at the neck increases, causing the neck to
melt and be separated into many small sections by quartz sand. In this way, the arc formed by the melting of the melt is divided into many
small sections by quartz sand, resulting in a smaller arc current and a smaller distribution space. Additionally, since quartz sand is insulating,
an insulator is immediately formed after the arc is extinguished, which disconnects the circuit
Characteristics of fast fuses
Inverse time current protection characteristics. Fuses have anti time delay characteristics, that is, when the overload current is small, the
melting time is long; When the overload current is high, the melting time is short. So, within a certain range of overload current and overload
time, the fuse will not melt and can be used continuously. Fuses have various melting characteristic curves that can be applied to meet the
needs of different types of protected objects.
Current limiting characteristics
Due to the fact that the melt of the fast fuse is a rectangular thin sheet with a series of circular holes and narrow necks, and filled with quartz
sand arc extinguishing medium. The cross-sectional area of the narrow neck of the circular hole is small, and the heat capacity is small. When
a short circuit fault occurs, the fault current has not yet reached the expected short circuit current, and it is melted, and the arc is divided into
many small sections by quartz sand. This not only limits the increase of short-circuit current, but also accelerates the extinguishing of the arc
Strong breaking ability
When a short circuit fault occurs, the narrow neck of the circular hole is the first to melt, and the arc is divided into many small sections by
quartz sand, which quickly extinguishes the arc. Due to the insulating nature of quartz sand, once the arc is extinguished, the fuse
immediately becomes an insulator, disconnecting the circuit. Therefore, the fast fuse has strong breaking ability, which can reach up to 50kA.
The impact energy borne by the load equipment is small
When a short circuit fault occurs in the circuit, the impact energy borne by the load equipment is
W=I²Rt
In the formula, I – short-circuit current; R – resistance of the circuit; T – The time from the occurrence of a short circuit fault to the
disconnection of the circuit. The fast fuse has a short breaking time and good current limiting effect, so the impact energy borne by the load
equipment is small
