Question 323Electricity & Electronics - QMED

The correct answer is B) to prevent damage to the meter movement from heat generated by the internal shunt. External shunts are used with ammeters to prevent damage to the meter movement from the heat generated by the internal shunt. The internal shunt carries the full current being measured, which can generate significant heat. By using an external shunt, the meter only needs to measure a small portion of the current, reducing the heat load on the meter movement and protecting it from potential damage. The other answer choices are incorrect because: A) external shunts do not affect reactive power factor error, C) they do not increase meter sensitivity, and D) the resistance of the external shunt is not the primary reason for using it.