What is fuse in electrical,types, properties,material of fuse wire

Hello guys welcome to my blog. Hope you are all good and well. 

Today we will discuss about,

  • What is fuse in electrical?
  • Need of fuse?
  • Materials of fuse wire?
  • Properties of fuse wire
  • Working principle of fuse
  • Working of fuse
  • Rating of fuse
  • Time taken by the fuse wire
  • Types of fuse
  • Advantages of fuse
  • Disadvantage of fuse
  • Applications of fuse

Now let’s go to discuss about, 

What is fuse in electrical: -

The fuse is a piece of metal or conductor of very low resistance connected in series with the equipment or circuit to protect from overload or over current.  

What is fuse in electrical,types, properties,material of fuse wire
Fig. Fuse connected in series

Need of fuse: -

  • As definition tells us, it is used to protect the equipment in overload condition. 
  • If equipments or large machines directly connected to the supply and then any fault occurs in the equipment a high short circuit current will flow through the equipment and damage it. 
  • So to avoid this damage a fuse wire is connected in series with the machine to protect in case of over current or overload.

Material of fuse wire:-

Material of fuse wire may be copper, silver, aluminium or alloy of tin (63%) and lead (37%).

Properties of fuse wire: - 

The fuse wire should have following properties for the better operation: -

  1. Low melting point 
  2. High conductivity
  3. Time-inverse characteristics

Working principle of fuse: -

  • It works on the principle of "heating effect of current" i.e. when a high current pass through a conductor or a metal piece, high heat will produce in it which melts the conductor
  • Fuse wire is connected in series to the machine or equipment requires protection and whenever this equipment or machines takes the current more than the fuse rating, the fuse will melt. 
Note: -
Fuse wire should always connected in series with the equipment or machine so that all current taken by the machine, first pass through it. 

Working of fuse: -

The fuse is connected in series with the equipment or machine to be protected and conducts the normal rating of current without overheating (in normal conditions) but whenever a fault occurs and the current taken by the machine is more than the fuse rating, the fuse will get overheated and melts. As fuse gets melted the circuit will in open condition, no current flow through a circuit or machine. 

What is fuse in electrical,types, properties,material of fuse wire
Fig. Fuse after blow out

Rating of fuse: -

A question arises here that how to identify the rating of the fuse? 

So there is a formula from which you can determine the required rating of fuse. And then bought it from the market.

Fuse rating = (Power / voltage) × 1.25 ampere 

If power is 1kw and voltage is 440 volts, then the fuse rating will be, 

= (1000 / 440) × 1.25

= 3.12 A 

So we will use a fuse of standard rating which will near to this value. 

  • It should be noted here that a proper rating fuse should used for any machine or equipment. 
  • If an improper rating fuse is used, then it will not protect the machine from overload or disconnect the load without any over current in the circuit. 
  • For example, let assume a machine requires fuse rating of 10 A means here the machine will damage when current flows through it more than 10 A. And you connect a 5 A fuse wire in series with that machine, then the fuse will disconnect the machine from the supply at 5 A which may be a normal running rating of the machine. 
  • In same case, let assume you connect 15 A rated fuse then, when machine takes current more than 10 A  fuse will not melt until current reaches to 15 A and machine will damage at this time. 

Time taken by the fuse to melt: -

The time taken by the fuse is totally depends upon its time inverse or time current characteristics as you can see in fig. Below. 

What is fuse in electrical,types, properties,material of fuse wire
Fig. Time-current characteristics of fuse

Here we can note that the higher the value of current lesser the time required to blow out by the fuse. 

Types of fuse: -

On the basis of operating voltage there are mainly two types of fuses are used: -

  • Low voltage fuse
  • High voltage fuse

Low voltage fuse: -

The fuse which is used below 1kv is known as low voltage fuse. These types of fuses are generally used in domestic installations, motors and low voltage distribution lines, etc. These are further classified into two parts: -
  • Rewirable fuse
  • HRC fuse

High voltage fuse:-

As the name suggests these types of fuse are used in high voltage circuit applications. These are also further Subdivided into two parts: -
  • Cartridge type high voltage fuse 
  • Liquid type high voltage fuse.

Advantages of fuse: -

  • As only one wire is used in fuse as a fuse element for protection of the machine so this is a cheapest in cost. 
  • It does not require any maintenance after installation. 
  • It interrupts the supply very rapidly if the fault current is high. (As discussed above in time-current characteristics)
  • It is compact in size, therefore less space required to place it. 
  • It does not produce any noise during its operation. 

Disadvantages of fuse: -

  • As it melts so we have to replace the fuse after every operation.
  • Improper size or rating of fuse may damage the machine so we have to take a proper rating of fuse. 

Applications of fuse: -

It is used to protect,
  • Motors
  • Transformers
  • Air conditioners 
  • Domestic installations 
  • Electronic circuits, etc. 

Conclusion: -

  • The fuse is used for the protection of machines or circuits inserted in series so that total current taken by the machine or circuit is passed through the fuse first then from the circuit. In any abnormal condition fuse gets melt and protect the circuit. 
  • It should be highly conductive and low melting point so that it gets melted whenever high temperature is obtained. 
  • It will melt rapidly if the current is high which is a most suitable characteristics of the fuse. 

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Hope article helps you. 

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