Abstract :
This paper describes a perfection of the dynamometer method of harmonic analysis in which accuracy and speed of operation have been combined with portability. Although intended primarily for the analysis of voltage waves on power circuits, where it gives the harmonics correct to 1/29th of 1 per cent of the fundamental, the method can also be used for the analysis of current waves and for finding the phase angle between harmonics of the same frequency in two different waves. Each harmonic is found separately from steady readings on two instruments. In the dynamometer method of analysis, a current related in some known way to the voltage or current to be analysed is passed through one coil of a dynamometer instrument, while through the other is passed a sinusoidal ¿analysing current¿ of exactly the frequency of the harmonic required to be found. The special feature of the present method is the production of the ¿analysing current¿ by means of a synchronously-driven contact disc of special design and a valve circuit. The paper describes in detail the operation of the analyser and establishes its accuracy. A few examples of its use are also given.
