OR
The Aryton shunt eliminates the possibility of‟ having the meter in the circuit without a shunt. This advantage is gained at the price of slightly higher overall Aryton shunt ammeter. In this circuit, when the switch is in position “1”. resistance Ra is in parallel with the series combination of Rb, Rc and the meter movement. Hence the current through the shunt is more than the current through the meter movement, l thereby protecting the meter movement and reducing its sensitivity. If the switch is connected to position „2‟, resistance Ra and Rb arc together in parallel with the series combination of Rc and the meter. Now the current through the meter is more than the current through the shunt resistance. If the switch is connected to position “3” Ra,Rb and Rc are together in parallel with the meter. Hence maximum current flows through the meter movement and very little through the shunt, This increases the sensitivity.
Advantage of using Aryton shunt.
1. On a multiple-range ammeter, the Ayrton shunt is frequently a more suitable design.
2. One advantage of the Ayrton shunt is it eliminates the possibility of the moving coil to be in the circuit without any shunt resistance where they protect the deflection instrument of the ammeter from an excessive current flow when switching between shunts.
3. Another advantage is that it may be used as a wide range ammeter.