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 quartzs and 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