An oscillograph for the automatic recording of disturbances on electric supply systems

The paper briefly mentions earlier instruments of the type indicated by the title and goes on to describe a fully automatic oscillograph in which 15 cathode-ray tubes, housed in a common camera, may be photographed side by side on a common 70-mm film. The equipment is normally quiescent, and the cathode-ray tubes are blacked out, but any abrupt change of the supply voltage influences a detector which initiates the cathode beams and starts a film-driving motor. Recording is effective right from the outset of the system disturbance, as an electronic sweep of the cathode-ray beams anticipates, and merges into, the mechanical acceleration of the film. On selected elements, time-delay networks provide signal storage, enabling events preceding the disturbance by about 1 millisec to be included in the records. A code number for the date and time of each operation is marked against the corresponding record. The equipment is capable of giving detailed service records of modern high-speed switchgear and protective equipment.