F. H. Richardson's bluebook of projection (1942)

18 RICHARDSON'S BLUEBOOK OF PROJECTION Suppose that the negative side of the upper circuit of Fig. 2 and the positive side of the lower circuit of that diagram were grounded to earth; the dotted line would then represent the earth conductivity. The electrical condition would exactly duplicate that shown in Figs. 1 and 2, nevertheless there would be no waste in the form of an "earth" current. Only a charging surge flows through ground, and that only when the connection is first put in, or the generators first start operation. However, if one generator should gain or lose voltage with reference to the other, proportionate equalizing surges, still of no practical importance, would pass through the dotted line connection. (40) A very different state of affairs exists if a connection like the dotted line of Figs. 1 and 2 is installed on circuits where the two generators are not completely independent of each other, or in cases where there is only one generator supplying both lines. Such an arrangement is shown in Fig. 3. Note g :trt 5-5-5 ^t=^Q Figure 3 that in that diagram electrons from the negative side of the generator can move down the dotted line, and then back upward through the next line to the left until they reach the positive side of the generator, thence proceeding through the generator to its negative terminal and so going round and round. In such cases the generator is said to be "short-circuited," because the electrons have a short-cut path