Difference between dynamometer wattmeter and induction type wattmeter
Answers
Answer:
Explanation:
The torsion heads carry a scale, and when in use, the moving coil is bought back to the zero position by turning this head; the number of divisions turned through when multiplied by a constant for the instrument gives the power.
Eddy currents are eliminated as far as possible by winding the current coils of standard wire and by using no metal parts within the region of the magnetic field of the instrument.
The mutual inductance errors are completely eliminated by making zero position of the coil such that the angle between the planes of moving coil and the fixed coil is 90 degree. i.e. the mutual inductance between the fixed and moving coil is zero.
The elimination of pivot friction makes possible the construction of extremely sensitive and accurate electrodynamic instruments of this pattern.