[Electric engineering.] . two-phase system,the aim should be to get the load on the two phases asnearly balanced as possible. Of course, where motors areoperated, both phases are used, and, hencer there is notmuch danger of an unequal division of load. When lampsare connected, one transformer or set of transformers atone point on the circuit can usually be balanced againstanother group at some other point, so that the load on thewhole will be equally divided, as indicated in Fig. 30 shows a number of different methods of connectingtransformers on a two-phase system, using three line wi
[Electric engineering.] . two-phase system,the aim should be to get the load on the two phases asnearly balanced as possible. Of course, where motors areoperated, both phases are used, and, hencer there is notmuch danger of an unequal division of load. When lampsare connected, one transformer or set of transformers atone point on the circuit can usually be balanced againstanother group at some other point, so that the load on thewhole will be equally divided, as indicated in Fig. 30 shows a number of different methods of connectingtransformers on a two-phase system, using three line this case, the central wire acts as a common return, andthe voltage between the outside wires is times that ofeach phase. The same remarks apply here as in the previ-ous case, and the three-wire arrangement shown at (b) is notas generally satisfactory as that shown at (V). In bothcases the primary pressure is shown as 2,000 volts, andtransformers with a ratio of 20 to 1 are taken for the sakeof § 14 ELECTRIC TRANSMISSION. 69 TRANSFORMERS OjNT THREE-PHASE CIRCUITS. 81. It is customary in America to use three single-phasetransformers for transforming from one pressure to anotheron three-phase circuits. In Europe, three-phase trans-formers are used in which there are three primary coils andthree secondary coils wound on a three-legged iron core. InAmerica, the general practice is to use three standard single-phase transformers connected up either Y or A, as the casemay be. With the A arrangement, the power supply willnot be entirely crippled even if one of the transformersshould become damaged. In some cases the primaries areconnected across the lines according to the Y scheme, asshown at (a), Fig. 31. By using the Y connection, there aretwo primary coils in series between any pair of mains, and,consequently, the pressure on any one primary coil is lessthan that between the mains; the pressure on each primaryis equal to the pressure between the mains d
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