An oscillograph investigation of the gulstad relay

The paper deals with an examination, by means of the oscillograph, of the details of the current-changes in the auxiliary and line circuits of the Gulstad high-speed vibrating relay. The results include:¿ (1) Variation of the current in the two branches of the auxiliary circuit. (2) Resultant of the auxiliary currents determining the magnetization of the relay cores. (3) Influence of leak circuits. (4) Effect of a closed line circuit and operation of the line currents. The circuit connections used in the tests are given and a new type of frequency meter devised by the author is describe