When safety fuse is worked in a circuit?

 

When safety fuse is worked in a circuit?

Fuse

Fuse is an electrical safety device that protects our circuit from over current, making our circuit safe.

 

 How does Safety fuse circuit work

I will tell you how the fuse works. See what happens in it that we select our fuse according to the current that our circuit needs to work. Just like an external current is   exceeded from our fuse current rating then our fuse gets burnt in that case which prevents our circuit from malfunctioning. In fact, the function of fuse is that in case of over current or short circuit, burning itself protects our internal circuit. Hence we also call it safety fuse.

Fuse symbol

How to choose Fuse 

To find out how much Amp will be used in our instrument, we have to keep some things in mind. For the instrument in which we have to pu the fuse, we should know its primary voltage, secondary voltage and current. We will find out the primary current from it and then we will find the current rating of fuse.

Vp = Primary voltage 

Vs = Secondary voltage

Ip = Primary current 

Is = Secondary current 

Vp/Vs = Is/Ip

 

इसी तरह से-->

Ip = Vs X Is / Vp 

Fuse rating = Ip X 1.25

For example==>  Vs = 22V ,  Is = 2.5A , Vp = 220V then calculate the fuse rating.

Sol----- Ip = Vs X Is / Vp 

                

            Ip = 22 X 2.5 / 220

              

           Ip = 0.25A(250mA)

          Fuse rating = Ip X 1.25

 

          Fuse rating = 250 X 1.25

 

          Fuse rating = 312.5 ≈ 300mA

So our 2.5 A instrument will have a fuse of 300mA, which will protect our instrument from over current or short circuit.

What material is fuse made of   

Inside the fuse is a wire strip which is made of tin, lead, zinc, copper, silver metal. They have some special properties, so they are used as fuse wire. These properties  are something like this.

1) Their melting point is less.

2) They have low ohmic loss.

3) Their conductivity is high.

4) Due to conductivity high, their resistivity is low.

5) Their cost is low.

The fuse is designed in such a way that it can melt easily in case of over load or short circuit. The thickness of the wire of the fuse varies and depends on how much current we have to flow into the fuse. The current rating of fuse also varies according to the different current. Usually we use fuse of material made from lead and tin as their melting point is low.

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Ishan Kumar