Why fuses are used

It prevents damage that occurs due to mismatched loads. Prevents blackouts: if any dis-function occurs in the components of the circuit, the nearest circuit breaks. Information about the ampere rating, voltage rating, approval standards of the fuse and interrupt rating are generally marked on the fuse. This information must be checked and verified before buying a fuse. An electric fuse is based on the principle of heating effect of electric current.

It is made up of thin metallic wire of non-combustible material. A fuse is always connected between the ends of the terminal in a series connection with the circuit. When an excessive current flows in the circuit, it generates heat in the circuit which leads to melt the fuse due to its low melting point, and it also opens the circuit. The excessive flow of current may lead to breakdown of the circuit and stop the current flow.

Once a fuse melts, it can be changed or replaced with a new fuse. A fuse is normally made up of elements like zinc, copper, aluminum and silver. A fuse acts as a circuit breaker and breaks the circuit in case any fault occurs in the circuit. It acts as a protector of electric appliances and also as a safety measure for humans.

They detect faults and then stop the flow of electricity. Small circuit breakers protect individual household appliances, whereas larger ones can protect high voltage circuits supplying electricity to entire cities. Fuses and circuit breakers Fuses and circuit breakers protect electrical circuits and appliances.

Fuses The fuse breaks the circuit if a fault in an appliance causes too much current to flow. A 13A fuse contains a low melting point wire Fuses in plugs are made in standard ratings. Selectivity Fuses can be easily coordinated to provide selectivity under both overload and short-circuit conditions. Minimal maintenance Fuses do not require periodic recalibration as do some electromechanical overcurrent protective devices.

Long life As a fuse ages, the speed of response will not slow down or change. Ampere Rating: The continuous current carrying capability of a fuse under defined laboratory conditions.

The ampere rating is marked on each fuse. Available Fault Current: The maximum short-circuit current that can flow in an unprotected circuit. Coordination: The use of overcurrent protective devices that will isolate only that portion of an electrical system that has been overloaded or faulted.

Element: A calibrated conductor inside a fuse that melts when subjected to excessive current. The element is enclosed by the fuse body and may be surrounded by an arc-quenching medium such as silica sand. The element is sometimes referred to as a link. Fast-Acting Fuse: This is a fuse with no intentional time-delay designed into the overload range. Values may be from hundreds to many thousands of amperes. Ferrule: The cylindrical brass, bronze or copper mounting terminals of fuses with amp ratings up to 60 amperes.

The cylindrical terminals at each end of a fuse fit into fuse clips. Current-limiting Fuse: A fuse that meets the following three conditions: Interrupts all available overcurrent within its interrupt rating. Within its current limiting range, limits the clearing time at rated voltage to an interval equal to, or less than, the first major or symmetrical current loop duration. Limits peak let-through current to a value less than the available peak current.