Definition: Electrodynamometer Wattmeter is a machine whose function is related to the reaction between the magnetic fields of a fixed coil and a moving coil. It is used for both AC circuits and DC circuits. The working principle of the Electrodynamometer Wattmeter is very straightforward and simple. Its function depends on the principle that a current-carrying conductor placed in a magnetic field experiences a mechanical force. This deflects the mechanical force indicator mounted on a calibrated scale.