Complete Synchronous Motor Excitation Characteristics

Synchronous motor excitation characteristics published hitherto have been incomplete. If theoretically determined, while forming closed loops, some doubt as to their accuracy has been entertained. When determined experimentally, thay have not been complete, in that the so-called unstable portions of the curves have not been obtained, and generally speaking, the upper portions of the characteristics have been missing. This paper shows complete synchronous motor characteristics, experimentally determined, differing materially from published curves determined by theory. These differences are discussed, and their cause attributed to variations in synchronous impedance. Experimental data is included showing the factors on which synchronous impedance depends, and how it varies with current, saturation and power-factor.