The quadrant electrometer
John F. Sutton · Journal of Scientific Instruments · 1927
The paper is intended to be an analysis of the principles involved in the practical design of the quadrant electrometer with special reference to its use as a wattmeter for calibration purposes. It indicates briefly the advantages of the electrostatic method for the measurement of power, and refers to the extreme difficulty experienced in manipulating the early types of instrument. A description is given of the chief points in the design of the Standard Electrometer constructed at the Reichsanstalt in 1907, and reference is made to the instrument installed at the N.P.L. in 1912. A list is given of the conditions which are essential to the design of an instrument having a straight line law, and a criticism of some of the devices which have been adopted to conform to these requirements. In conclusion, a design is given of an instrument suitable for commercial purposes which can be constructed in such a manner as to ensure the maximum degree of accuracy and to provide the minimum number of adjustments.