What is the purpose of the electrical fuse

Electronic components / electromechanical components / fuse

What does a backup [edit]

The task of a fuse is to protect electrical devices, their components and lines, depending on their use. A fuse protects against overload or a short circuit.

  • Overload means that too much current is flowing in a circuit (too high amperage).
  • A short circuit is a low-resistance connection between two potentials (also resulting in an excessively high current intensity).

In a circuit, the weakest component is often the first to be destroyed. Then he is interrupted. As a rule, this weakest component should be the fuse.

What is it made of [edit]

Basically, a fuse for electronic circuits consists of a stable housing and wire that melts in the event of an overload or short circuit. In this way, the fuse ensures safe separation.

A fuse must never be repaired or bridged

Characteristics of a backup [edit]

There are slow and fast fuses. Slow-acting fuses trigger later than fast-acting fuses. Whether a fuse is slow or fast can usually be read on the housing.

There are the following categories:

  • Super nimble
  • Nimble
  • Medium latency
  • Sluggish
  • Super yields

A fuse always has a nominal current. If the rated current is exceeded, the fuse trips.

There are also mistakable and distinctive microfuses. As the name suggests, interchangeable fuses can be confused, since e.g. a 0.06A fuse looks exactly like a 0.6A fuse.

It is not possible to mix up the unmistakable ones, as the fuses here are getting bigger or longer depending on their rated current. Because a 0.6A fuse is longer than a 0.06A fuse, the 0.06A fuse cannot be pushed into the 0.6A fuse holder because it is too short.

In addition to the ampere value, many fuses also have a maximum voltage specified. This voltage must not be exceeded, otherwise a safe separation of the circuit can no longer be guaranteed. A micro fuse that is designed for 50 volts, for example, must not be used for protection in a 230V network. Otherwise, an electric arc could occur when it burns through, which does not go out and can cause damage. The contact distance in the fuse is decisive up to which voltage it can be used.

Securing the household

What happens if a defect such. B. Does the metallic housing of the washing machine get live? The housing is earthed via the protective contact. The short-circuit current flows through the protective contact, the residual current circuit breaker (formerly FI switch, now called RCD) trips and switches the circuit free. This usually happens before the fuse is switched off. If there is no residual current circuit breaker, dangerous situations can arise if the current flow via earth is too low for the fuse to trip. About 30 milliamps (mA) through the human body can be fatal, and about 100 mA can cause burns. Both are well below the classic standard fuse values ​​for households of 10 or 16 amperes.

The dimensioning of the fuse in the household circuit depends on the cross-section of the installed lines. In older houses you will often only find 6 ampere fuses, as there used to be only a few electrical devices and therefore thinner cables were drawn in. Replacing such a fuse with a stronger one is dangerous, as the lines and junction boxes can become too hot in the event of an overload and there is a risk of fire. The same applies, for example, when laying power lines through hollow walls that are usually insulated. If more current is required - i.e. if fuses are required for higher current - the cables must also be replaced by thicker ones.

Examples of backups [edit]

  • NH fuse
  • Microfuse
  • Diazed fuse
  • Neozed fuse
  • Car security

Links [edit]