Fuse ,Principle of Fuse, Materials used for fuse wire, Types of fuse,reasons to use a fuse, Common fuse terms

History of Fuse

                    A french Physicist Namel Breguet was famous for his effort in the initial days of telegraphy.He suggested the utilization of reduced part of conductors to guard telegraph stations against the hits of lighting with liquefying , the slighter wires would guard equipment along with wiring in the building . In the year 1864, lighting installation and telegraph cables can be protected by employing a variety of foil fusible essentials and wires, Finally , Thomas Alva Edison has patented a fuse as an element of his electric distribution system in the year 1890.
Principle of Fuse

                   Fuses are sacrificial devices used to protect much more expensive electrical components from the damaging effects of overcurrent.Fuses consist of a low Resistance metal or wire that is used to close a circuit.When too much current flows through the low resistance element of the fuse, the element melt and break the circuit.
Materials used for fuse wire

                   The material used for fuse elements must be of low melting point, low ohmic loss , high conductivity ( or low resistivity) low cost and free from detraction. The material used for making fuse element has a low melting point such as tin , lead or zinc.
Types of Fuses

                    There are main two types of fuses are .
1-AC Fuses.
2-DC Fuses.
                     AC fuses are further categorize in two main branches.
1-Low voltage Fuses.
2- High Voltage Fuses.
                       High voltage fuses are further divide.

1-Cartridge type HV HRC Fuses.
2-Liquid type HV HRC Fuses.
3- Expulsion type HV Fuses.

2-Low Voltage Fuses.
                     Low voltage Fuses are further divide .
1-Switch Fuse.
2-Striker fuse.
3-Rewirable type fuses.
4-Drop-out fuse.
5-Cartridge type fuses.
                     Cartridge type fuses are further categorize as.
1-Bolted type HRC link fuse.
2-knife Blade type HRC link fuse.
Reasons to use a fuse

  1. Safety.
  2. Cost effective.
  3. High interrupting rating.
  4. Reliability.
  5. Component Protection.
  6. Minimal maintenance.
  7. Long life.
Common Fuse terms

  • (I)2t (Ampere Squared Seconds)  A measure of the thermal energy associated with current flow.Where t is current flow in seconds.
  • Clearing (I)2t   The total I2t passed by fuse as the fuse clears a fault, with t being equal to the time elapsed from the initiation of the fault to the instant the fault has been cleared.
  • Melting (I)2 t    The minimum I2t required to melt the fuse element.
  • Ampare Rating    The continuous current carrying capability of a fuse under define laboratory conditions.
  • Available Fault current    The maximum short circuit current that can flow in an unprotected circuit.
  • Current Limiting Rang     The available fault currents a fuse will clear in less than 1/2 cycle thus limiting the actual magnitude of current flow.
  • Element   A calibrated conductor inside a fuse that melt when subjected to excessive current.
  • Fast Acting Fuse   This is a fuse with no intentional time delay designed into the overload rage.
  • Fault Current    short circuit current that flows partially or entirely outside the intended normal load current path of a circuit component.
  • ferrule    The cylindrical brass , bronze or copper mounting terminals of fuses with amp rating up to 60 amperes.
  • Current Limiting Fuse   A fuse that meets the following three conditions.
  1. Interrupts all available overcurrent with in its interrupt rating.
  2. With in 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.
  3. Limits peak let through current to a value less than the available peak current.
  • Interrupting Rating    The maximum level of fault current that the fuse has been tested to safely interrupt.

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