Abstract :
THIS SUBJECT of insulation co-ordination has been an active one for the past 10 years or so. It was initially presented and discussed in 1928.1 Since then, the subject was taken up by practically all groups interested in the transmission problem including designers and operators of electric systems. As the study of the problem gathered headway, the need for further investigation work became quickly apparent. A great number of individual researches were thus started. All of them although closely related were not entirely coordinated. Each of them, however, in its own way, arrived at a solution of all, or of a part of the problem of co-ordinating the insulation strength of the electric system.
