What is Swamping Resistance And Why Swamping Resistance used in Ammeter?

WHAT IS SWAMPING RESISTANCE?

Before you know about what is swamping resistance you have to know,

What is Swamping?

"Swamping means overwhelm or overwhelm with an excessive amount of something;".i think you understand.

I think you all know about the resistance. But you think what does the swamping term come and why? don't worry I am going to explain it. Ok.. a normal resistance is very much temperature sensitive as you studied in previous articles. 

"Swamping resistance is a resistance having a very low temperature coefficient of resistance and its resistance is 20 to 30 times more than the resistance of coil connected in series with it "

Swamping Resistance Material - 

Example - manganin and other partially insulating materials.

If you don't know the construction and operation of an ammeter then go to our ammeter and voltmeter section. you will find there the coil of the ammeter is also temperature sensitive i.e its resistance varies with temperature.

Case-1 ( when there is no swamping resistance)

NO SWAMPING RESISTANCE CONNECTED

In the above figure, there is no swamping resistance and it is shorted. you know the deflection of the ammeter is proportional to the current flowing through it. So when there will a rise in temperature resistance also varies and hence current in the coil changes. so in this situation, the meter will not show the actual value of the current under measurement. hence the error percentage increases.

Case-2 ( when there is a swamping resistance)

SWAMPING RESISTANCE CONNECTED

Now consider that swamping resistance is connected as shown in the figure. you know from the definition that it is a resistance of a very low-temperature coefficient and Its resistance is equal to 20 to 30 times the resistance of the coil used in the ammeter. so the coil resistance will be very small as compared to the swamping resistance connected in series.

                                            Hence the problem is solved. the change in resistance value due to a change in temperature can now be neglected. because this small value can't affect the current flow through the coil.

                                     By this method, the error can be reduced to some negligible value and we can't completely eliminate this error.




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