Oscillographs for Recording Transient Phenomena

S C I L L O G R A P H S are described which were developed primarily for recording transient phenomena of which the time of occurrence is neither known nor subject to control. The specific apparatus described was designed primarily for recording transient inductive disturbances in communication lines from neighboring power circuits. When the design of this apparatus was begun, there was no satisfactory way for determining the duration, frequency or wave form of such disturbances, although apparatus was available by means of which the approximate magnitude of such transients could be determined, and, by constant supervision, the time of their occurrence. It was with the idea of determining part or all of these factors automatically in a single record that the oscillographs to be described were developed. Transients in general may be of various types. They may have components in a large range of frequencies, they may occur in a large range of amplitudes and may be very long or very short or intermittent. Attention was directed toward recording devices which would obtain records of any disturbances in excess of a predetermined magnitude regardless of the time of occurrence. For practical reasons it was necessary also to give attention to the cost of operation, the power consumed, and the amount of servicing in operation. To meet these requirements two somewhat different types of oscillograph were developed. One is capable of making records of short duration having uniform resolution throughout.