Fig. 785.—Arrangement of feeder and mains in parallel system. By locating the feeder at the electrical center, less copper is required for the mains. The cut does not show the fuses which in practice are placed at the junction of feeder and main.
Ques. What is the usual arrangement of parallel systems?
Ans. Conductors known as a feeder run out from the station, and connected to these are other conductors known as a main to which in turn the lamps or other devices are connected as shown in [fig. 785].
Ques. In what two ways may feeders be connected?
Ans. They may be connected at the same end of the mains, known as parallel feeding, or they may be connected at the opposite end of the main, called anti-parallel feeding.
The main may be of uniform cross section throughout, or it may change in size so as to keep the current density approximately constant. The above condition gives rise to four possible combinations:
1. Cylindrical conductors parallel feeding, [fig. 786];
2. Tapering conductors, parallel feeding, [fig. 787];
3. Cylindrical conductors, anti-parallel feeding, [fig. 788];
4. Tapering conductors, anti-parallel feeding, [fig. 789].
