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Functions of Fuse

In the field of electrical engineering, a fuse is a device that aims at providing over-current protection in an operational electric circuit. It works on the principle where the fuse, essentially made up of a thin metal strip or the wire gets heated up when too much current flows through it and thereafter melts, therefore interrupting the flow of the current in the circuit. Generally, the fuse is made of one of the following metals:

  • Copper
  • Zinc
  • Aluminium
  • Silver
  • Alloys

The fuse is generally enclosed in a non-combustible housing and mounted in between a pair of electrical terminals. Always arranged in a series, this arrangement ensures that all the current passes through the protected circuit. The flow of current through the circuit gives rise to resistance in the fuse element, which leads to the generation of heat. When a current flow which is greater than the stipulated ampere rating of the fuse, the fuse melts either directly or melts a solder joint within the fuse due to the increased heat, and thus breaks the circuit without damaging the circuit components and the electronic appliances.

Once a fuse melts in an electrical circuit, it must either be re-wired or may be replaced, depending on the type of fuse being used

A list of the major functions of a fuse is given below:

  • Prevents short circuits: An aberrant connection between a couple of nodes of a circuit which are intended to be at varying voltages results in a short circuit, which may lead to overheating, fires and a massive damage to the electrical circuit. Short circuits may happen due to a low-resistance wire between the positive and negative terminals or due to breakage of insulation of a wire or even between two phases, leading to the generation of high resistance and consequent overheating. Such damage can be evaded by installing fuses or circuit breakers to disconnect the circuit in situations of excessive current flow.
  • Acts as an essential barrier between the circuit and the human body: A rise in temperature may lead to a potential explosion with a subsequent release of the electrolyte and hydrogen gas, which could lead to blindness and even death.
  • Prevents device failure due to faulty circuit operation
  • Prevents overloads of electrical circuits: Connecting too many electrical appliances over the same circuit often leads to overloading of the circuit beyond the circuit limit. In such cases, a fuse at the main panel or a circuit breaker at the main panel will terminate the circuit connection.
  • Prevents damage due to mismatched loads
  • Prevents blackouts: In case of a fault in any component in the circuit, the nearest fuse breaks; all the upstream components are free to operate without any interruption.

The markings on the fuse generally carry information regarding the Ampere rating, voltage rating, interrupting rating and approval standards of the fuse and must be verified and checked thoroughly before making a purchase.

Also learn about principles of LED here.

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