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Fuses are electrical protective devices that are commonly used in circuit design. They are designed to open a circuit with the flow of electric current and are usually situated on the line between the power supply and the load. Fuses can provide rapid detection and protection against overloads and short-circuits, preventing serious damage to electrical equipment and personnel.

The application field of fuses range from industrial control, automotive, lighting, instrumentation, computer or audio-video equipment to household appliances such as toasters and microwaves. Its advantageous features, such as quick response, low cost and reliable operation, make it the preferred protection component in most protection applications. Especially in industrial applications, fuses are commonly used in the protection of circuits with electric losses, leakage current and overvoltage.

A fuse usually consists of a metal wire or strip that is designed to melt when an excessive current flows through it. The melting of the wire results in a gap opening in the circuit and interrupting the electric current. Fuses come in different sizes and current ratings. Generally, a higher current flow will cause the fuse to heat up and eventually break at its specified rating. Once a fuse is blown, it needs to be discarded and replaced.

The material used for the fuse determines its characteristics, current rating and melt time. Typically, copper materials are used to create the fuse and other materials are used as a binder. Commonly, lead or a lead/tin alloy is used as the binder material. In most cases, fuses with lower electrical resistance generate less heat during operation than higher resistance fuses.

In the majority of modern day applications, quick-blow fuses are utilised as the main protection device. These fuses operate at the specified rating and then quickly melt when a greater current is present. They operate quickly and cut off the current within milliseconds, preventing damage to the electrical equipment. The quick-blow fuse can then easily be replaced in order to restart the circuit again.

With the potential of high current flow, fused circuits have become an important safety mechanism. Fuses are capable of cutting off electrical current in order to prevent any damage that could arise from overheating. The application field of fuses is very wide, therefore their working principle is an important factor for design engineers to consider.