Fault-current measuring device

IN electric power system operation numerous problems are encountered in analyzing the results of short circuits and in the physical location of the trouble. Some devices now available for analyzing short circuits in a-c circuits are the oscillograph, the annunciator ammeter, and a magnetic link device requiring rectifiers. The oscillograph is the most accurate device but is expensive. The annunciator ammeter provides a limited amount of data; however, it offers a high electric burden to the circuit and does not have closely graduated steps of reading.