Fuses: Application Field and Working Principle

Fuses are safety devices that provide protection for electric circuits. A fuse consists of a metal strip or wire fuse element, of small cross-section compared to the circuit conductors, mounted between a pair of electrical terminals, and (usually) enclosed by a non-combustible housing. The fuse element is made of a metal alloy that has a low melting temperature compared to the wires or components in the electric circuit. When an electric current in the circuit exceeds a specified level, the element melts and breaks the circuit, thus interrupting the flow of current.

Application

Fuses are used in dozens of applications. An increasingly popular application for low-voltage fuses is in electrical power distribution systems, such as an electrical utility’s power grid. The same distribution system is also used in commercial and residential buildings, where fuses are used to protect the wiring from overloads and short circuits. Automotive fuses are used to protect electrical components during the operation of the vehicle. Appliance and electronics fuses are used to protect the components, wiring, and other components within the device from overloads and short circuits. Industrial and high-power fuses are used in large-scale systems such as in electric power plants, factories, and commercial buildings. Low-voltage fuses are also used in panel boxes and other applications where low-level voltages are used.

Working Principle

Fuses differ in their working principles, but all operate in a similar fashion. When a current, either alternating or direct current, passes through the fuse, its metal strip (or wire) heats up. When the current exceeds a particular level, the strip heats up to a point where it melts and breaks the circuit. The current then stops and the power to the circuit is cut off. Fuses are designed to have a specific melting point, which varies depending on the application and the amount of current that is expected to flow. In most cases, the fuse can be reactivated by replacing it with a new one.

Types of Fuses

Fuses are available in a wide variety of types and sizes. Some of the most common types of fuses include blade fuses, solid-state fuses, resettable fuses, and thermal fuses. Blade fuses are typically used in automotive applications, and consist of a metal strip that melts when the current increases to a certain level. Solid-state fuses are generally used in consumer electronics, and are made up of a small electronic circuit, which automatically trips and interrupts the flow of current. Resettable fuses are designed with a thermal element that melts when the current increases to a certain level, and can be reset after the current is reduced. Thermal fuses are typically used in appliances and have a strip of bi-metallic material that melts when the temperature of the element increases to a particular level.

Fuses serve an important role in protecting circuits from damages caused by electrical overloads and short circuits. In many applications, the fuse acts as a last line of defense that can be replaced quickly and easily. While there are many types of fuses available, they all operate in a similar fashion by heating up and melting when the current exceeds a certain level, thus stopping the flow of current and protecting the circuit.