A new 12-element automatic oscillograph and application on the Bonneville power system

ONE of the important operating problems of the central station engineer is to analyze system faults, to find out what the faults were and how well the protective equipment functioned to clear them. These faults may occur anywhere on the system and at any time during the day or night. They may last only a fraction of a second, and the most important part may last less than 1/2 cycle or less than 1/120 second.