Electrical Equipments

Explain the working principle of dynamometer type wattmeter and also prove that the deflection torque is directly proportion to power consumed by the load in both a.c. and d.c. circuit.

What is wattmeter? Write is types. Explain the wattmeter which can measure ac as well as dc power with the help of construction and working principle.

Explain the construction and working principle of single-phase electro-dynamometer type of wattmeter and derive the expression of deflection for ac operation.