Theory of medium-frequency pulsating-field machines

A new method is shown for calculating the complete, including peak, characteristics of the pulsating-field machine. It provides the open-circuit, short-circuit and on-load characteristics. The Guy-type generator is analysed. The relations obtained are as simple as any of those known for common industrial-frequency generators. The characteristics are traced point by point on the basis of a magnetisation characteristic of the magnetic circuit (with the exception of the air gap) comprising only half of the magnetisation path surrounding an excitation notch. The main approximating assumptions have been experimentally tested. They are (a) sinusoidal operating conditions and (b) that the magnetomotive force of the iron portion of the magnetic circuit varies linearly around a median value, as a function of magnetic-flux density in the air gap. The method and the relations found contribute to a better knowledge of the qualities of these generators. Conditions for optimum operation are investigated and means to avoid a series capacitance are suggested.