The sizes of copper wire employed have weights of too, 150, 200 and 400 lb per statute mile, and have electrical resistances (at 60° F.) of 8.782, 5.8 55, 4.39 1 and 2.195 standard ohms respectively.
In practice the resistances r, r' are 9 Earth FIG.
These tests are in some cases repeated at another temperature, say 50° F., for the purpose of obtaining at the same time greater certainty of the soundness of the core and the rate of variation of the conductor and dielectric resistances with temperature.
The leakage through the insulator of the cable is compensated for by connecting high resistances between different points of the strip conductor and the earth coating.
Faults or any other irregularity in the cable may be represented by putting resistances of the proper kind into the artificial line.