An investigation of corona loss: Law of corona and dielectric strength

V. Karapetoff: The diagram of connections used by the authors permits of obtaining an oscillogram of the total current, consisting of a reactive charging component and an in-phase energy component. In some cases it may be of interest to obtain a picture of the latter component alone. Perhaps this could be accomplished by some differential arrangement; that is, by using a condenser which takes the same reactive charging current as the conductor under test but has practically no corona loss. The high-voltage side of the step-up transformer would then be wound for a double voltage, with the middle point grounded; the added condenser would be connected to the other terminal of the transformer, and the resistance R3 would be connected to the neutral point. Only the difference of the currents taken by the conductor under test and the perfect condenser would flow through R3.