Abstract :
During the past six years an investigation has been in progress to determine, by means of continuously-recording klydonographs, certain features of voltage surges (and primarily those due to lightning) on overhead lines. This account is based on E.R.A. Report Ref. S/T26, and is mainly concerned with the instruments and their auxiliaries. The subject matter is divided into six Sections. Section (1) is a brief and general account of the investigation, and mentions the factors necessitating improvements to the apparatus employed. Section (2) describes the improved klydondgraphs and gives an account of some of the defects overcome. The phenomenon of cyclic intermittent film motion is considered in detail. Section (3) deals with the potential-dividers, and the auxiliary equipment thereof, used in this investigation. Specific reference is made to the development of unit-type dividers. Section (4) deals with calibrations, and indicates the limitations of 50-cycle calibrations used for the estimation of impulse voltages. Calibrations performed at the Association´s laboratory are described, and the voltage limits and probable accuracy of recording are stated. Section (5) concerns the investigations in the field. A brief description of the tests is followed by an analysis of the results obtained. Section (6) draws conclusions from the six years´ work. Although only few records of surges due to lightning were obtained, both the apparatus and technique employed have been considerably improved, and valuable experience has been acquired. From this, conclusions and recommendations pertinent to the klydonographs and auxiliary apparatus are stated. The sparsity of lightning surge records, common with this type of investigation, permits only few and tentative conclusions to be drawn regarding the nature of lightning disturbances on overhead lines. Switching surges are mentioned briefly.
