An electronic circuit for studying hunting

Various methods have been devised for determining power-angle oscillations of synchronous motors during the period of hunting following a change in load. This article describes an electronic circuit for this purpose, in which a beam of light is reflected from a set of equally spaced mirrors clamped around the motor shaft or coupling to a photoelectric cell; the light Sashes reaching the photoelectric cell are amplified and impressed on the plates of a cathode-ray oscilloscope in such a way that the resulting beam pattern on the oscilloscope screen shows the power-angle oscillations directly.