The Quadrant Electrometer

The quadrant electrometer has long been recognized as a valuable instrument for measuring power in a-c. circuits, especially at low values of the power factor. Nevertheless, it has been used but little. This has been caused to some extent by the fact that Maxwell's treatment does not hold for all electrometers, and by the difficulty of determining its constant with alternating current. In this paper, the author has discussed the theory of the instrument from the viewpoint of power measurements and has reduced its general equation to a simple form. He has shown how its constants may be determined with continuous current, and that these constants also apply in a-c. power measurement. He has checked the theoretical calculations by experiments. Data of the determination of the constants of a given instrument with continuous current are given in the paper, as well as examples of the use of the instrument in the measurement of power in a number of alternating circuits having different characteristics.