Fuse (redirected from lighted the fuse)

fuse

In electrical engineering, a safety device that protects electric circuits from the effects of excessive electric currents. A fuse commonly consists of a current-conducting strip or wire of easily fusible metal; whenever the circuit is made to carry a current larger than that for which it is intended, the strip melts to interrupt it.

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(1) A protective device that is designed to melt, or blow, when a specified amount of current is passed through it. PROM chips are created as a series of fuses that are selectively blown in order to create the binary patterns of the data or machine language.

(2) To bond together.

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Fuse (electricity)

An expendable protective device that eliminates overload on an electric circuit. The fuse is connected in series with the circuit being protected. The components of a typical low-voltage high-power fuse are a fuse element or wire, an insulating material support and housing, two metal end fittings, and a filler (see illustration).

Power fuse assembly

The fuse element is a silver strip or wire that melts when the current is higher than the rated value. The melting of the wire generates an electric arc. The extinction of this arc interrupts the current and protects the circuit. The fuse element is connected to the metal end fittings which serve as terminals.

The filler facilitates the arc extinction. The most commonly used filler is sand, which surrounds the fuse element. When the fuse element melts, the heat of the arc melts the sand near the element. This removes energy from the arc, creating a channel filled with the mixture of melted sand and metal. The metal particles from the melting fuse wire are absorbed by the melted sand. This increases the channel resistance, which leads to the gradual reduction of the current and the extinction of the arc. The insulating support and the tubular housing holds the fuse elements and the filler, which also serves as insulator after the fuse has interrupted the current.

The interruption time is the sum of the melting and the arcing time. It is inversely proportional to the current, that is, a higher current melts the wire faster. The fuse operates in a time-current band between maximum interruption time and minimum meeting time. It protects the electric circuit if the fault current is interrupted before the circuit elements are overheated. The arc extinction often generates overvoltages, which produce flashovers and damage. A properly designed fuse operates without overvoltage, which is controlled by the shape of the fuse element and by the filler.

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