Electrical Fuse
A fuse is used for protecting electrical devices and components from over currents and short circuits. A electrical fuse works by interrupting the flow of current through the melting of an internal element.
General specifications
Listed below are common specifications that apply to electric fuses are:
* Fuse types: These include:
o Miniature: These fuses are available in dimensions of 5x20mm and 6.3x32mm.
o Subminiature or micro: Also known as micro fuses, these have very small dimensions (no principal dimension greater than 10 mm) and aresuitable for compact circuit board layouts.
o Midget: These refer to fuses that have 13/32" diameter.
o Automotive: These fuses are only used in automotive.
o Blade type: These fuses are typically used in low voltage, high current applications.
o PC board: These fuses are specifically used on PC boards.
o Protective: These fuses are used for protecting secondary circuits or low voltage ICs.
* Mounting: These include:
o Solderable or surface mount
o Solderable with leads
o Replaceable with holder or clips
o Performance Ratings
There are certain performance criteria that one must consider while selecting fuses. These are:
+ Voltage rating: It is the maximum voltage, up to which a safe fault current interruption will occur.
+ Current rating: It is the maximum continuous operating current of the circuit.
+ Rated breaking capacity: It is the short circuit current at which the fuse can blow without being destructed.
+ Interrupt rating: These can be high interrupt, medium interrupt, or low interrupt.
o Performance Characteristics
There are certain performance characteristics that one must consider while selecting fuses. These are:
+ Fast acting: These fuses are used in circuits that have inrush currents or where the over current must be quickly interrupted.
+ Time lag: These fuses are used in circuits where high starting inrush currents occur and decay gradually.
Operating temperature of fuse is another environmental parameter that must be considered.
* Material of construction: These include:
o Ceramic
o Sand
