components and property of the wire of an electric fuse.
Answers
The material mainly used for fuse element are tin, lead, silver, copper, zinc, aluminum, and an alloy of lead and tin. An alloy of lead and tin is used for small current rating fuses. For current exceeding 15A this alloy is not used as the diameters of the wire will be larger and after fusing the metal released will be excessive.
Beyond 15A rating circuit, copper wire fuses are employed. Copper wire suffers from the drawbacks that it operates at a rather high temperature if a reasonably low fusing factor is desired. There is thus a tendency for the wire to overheat with the result that its cross-sectional area and fusing current are gradually reduced, and premature melting of the wire may occur.
Silver is used as a fuse element because it has the following advantages
It does not get oxidized, and its oxide is unstable.
The conductivity of silver does not deteriorate with oxidation.
Owing to its high conductivity the mass of molten metal to be handled is minimized and thus operating speed is fast.