Monday, 2 March 2020

Electric Fuse and Why are Fuses used? Working, Types, Applications

Electric Fuse 

  • In Electrical or Electronic Engineering the fuse is used for safety of the devices. The fuse is usually an electronic device, which is used to protect circuit from over current, overload and make sure the protection of the circuit. 
  • An electrical fuse operates on the principle of heating effect of electric current. There are many types of fuse elements available but function of most of these fuses is the same. 
  • Ordinarily, a fuse is a short metal wire or strip, connected to a conductor on each end, and usually enclosed in a glass or other non conductive container.  The fuse is mostly used for protection purposes in residential.

Electric Fuse
Electric Fuse

Working Of Fuse

  • During normal operating condition, the current flowing through the fusing element is such that the rate of heat production in the fuse element is nearly equal to rate of heat dissipation from the fuse element and thereby they are will be no considerable increases of temperature of that fuse element.
  • It usually consists of a low resistance metallic wire enclosed in a non combustible material. 
  • Whenever a short circuit, over current or mismatched load connection occurs, then the thin wire melts because of the heat generated by the heavy current flow. 
  • This disconnects the power supply from the connected system. In normal operation of circuit, fuse wire is just a low resistance component and does not affect the normal operation of system connected to the power supply. 
  • In order to minimize the fuse arcing, DC fuses tends to be bigger than an AC fuses which increases the electrodes  to reduce the arc in the Fuse.

Why they are used?

  • Whenever there is a short circuit, overload or earth fault in the system, huge current starts flowing through the system conductor which leads to hide temperature rise of the conductor itself. 
  • If this huge current is not prevented, after certain time the heat generated from the conductor part is so high, it can melt the conductor itself along with damage the insulation parts of the equipment.
  • Even there may be a chance of fire hazard due to extremely high temperature in the system. As a whole  there will be permanent damage in the equipment.
  • To prevent this, the huge short circuit current should be allowed to flow through the system for very short time so that there would be any serious temperature rise. 
  • Actually during fault nobody can prevent the flowing of  huge over current through the system but the during of flowing of this huge over current can be limited by using electrical fuse.

Types Of Fuses

Fuses can be divided into two main categories according to the types of input supply voltage.
  1. AC Fuses
  2. DC Fuses

1. Ac Fuses
  • In the AC system voltage frequency changes its amplitude from zero to 60 times every second, so arc can be extinct easily. 
  • AC fuses are little bit small in size as compared to DC fuses. 

2. DC Fuses
  • In DC system when the metallic wire melts because of the heat generated by the over current, then then arc is produced and it is very difficult to extinct this arc because of DC constant value.
  • So in order to minimize the fuse arcing, DC fuse are bigger than the AC fuses which increases the distance between the electrodes to reduce the arc in the fuse.

Applications of Fuses

Fuses are used in many industrial electrical and electronic devices for protection 
  • Hard Disk Drives
  • Laptops
  • LCD Monitors
  • Automotive Systems
  • Battery Packs
  • Gaming Systems & Portable Electronics
  • General Appliances and Devices
  • Cell Phones
  • Printers/ Scanners


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