A fuse is an electronic component that regulates the flow of current in a circuit. It breaks a complete circuit when excess current more than the expected, flows through it. It main function is to avoid excess current from destroying electronic circuits and prevention of short circuits. Primarily a fuse is a sacrificial metal with low resistance and melting point which gets melted when excess flows through it in a circuit. The excess current causes heat to form on it thus it breaks the circuit when melted.
The electric fuse was invented by Thomas Alva Edison in 1890.
Characteristics of a fuse.
1. Current rating.
This is the maximum current an electric fuse can accept or flow through it without breaking down.
2. Voltage rating:
it is the maximum voltage that can be applied to a fuse. A 12v fuse musn't be use in 100v, or else it will end it destroyed.
3. Response characteristics. this depicts the efficiency and reliability of the fuse. It is the speed at which a fuse blows when excesss current flows through it. It depends on the nature of the material use in producing it. Fuses that responds quickly to over current are ultra-fasts while those are slow to responding are slow burn fuse. Slow burn switchs are use in motor control circuits because they don't respond quickly but blows off on prolonged short circuiting, because motors pulls a lot much current when starting than when in operation.
Types of fuses.
These types of fuses the includes.
1.DC fuse.
It is use mainly in DC circuits to avoid excess current from protuding which can cause fire and damage to electronic components and ICs. There are many types of DC fuse which are classified according to sizes and working principles they are listed below.
- Catridge fuse.
It consists of two metal caps use for connecting the fusable wire which is enveloped in a transparent glass to circuit boards. It is removable and replaceable when damaged by excess current. When the fuse melts it can be easily noticed because of the transparent enclosure.
- Resetable fuse.
This type of fuse is used in situations where they can't be replaced when broken down. It disconnects a circuit completely when current above it rating passes through it and forms a closed connection when little or normal current flows through it. It's also known as PPT with a full meaning of polymetric polymer temperature co-effecient device, which is a type of passive component that prevents short circuits and excess current flow.
- Thermal fuse.
This fuse is made of temperature sensitive material which shuts down a circuit when excess current flowing through it develops heat, and forms a closed circuit when moderate current flows through it.
- SMT fuse.
It is very small in size and mostly use in PCBs and portable devices. It can be found on cellphones, laptops and chargers.
2. AC fuses.
They are use in AC circuits they appear bigger than DC fuses but of no much difference.
Fuses are commonly use in AC circuits than DC circuits due to potiential voltage that can flow through them. Most common are listed below;
- High voltage fuse.
It is use in high power applications like protection of Instruments transformers and distribution transformers. The fuse element are usually made from copper, tin or silver
- Rewireable
Tags:
Basic Electronics