A Cathode Ray Oscillograph with Norinder Relay Its Design and Application

The paper describes the Norinder cathode ray oscillograph as used in lightning investigations on transmission lines in 1928. It then describes a new model of a cathode ray oscillograph developed for the expansion of field and laboratory tests in 1929. One of the novel features of this modified instrument is the steel housing. A circuit is shown for obtaining a unidirectional time axis on the oscillograms, in which the timing movement is started by an impulse from the surge to be measured. In the appendix a simple and concise formula for the sensitivity of a cathode ray oscillograph is developed. This has been derived by Mr. Lewis R. Smith and takes into account the change of the mass of the electron at speeds approaching that of light. At the frequently used cathode voltage of 60 kv., this phenomenon already causes a deviation of 5 per cent from the value which would be expected otherwise.