One can build a Delta generator or power supply with 480V between phases, for example. The reason there's so much less potential against ground is because the voltage is developed across the phases -- each phase is 120 degrees out of sync with the other two. Since each phase is matched against one of the other two in the end device being powered, no phase has to carry the full maximum voltage (against ground, that is) to be developed in the end device at any single time.
Delta may not be as flexible in application as Wye, and each phase carries less power than the respective phases in Wye, but it is cheaper to build and cheaper to wire. That's a very convincing reason to use it in several applications, particularly in avionics. (Not only is it cheaper to wire, but the the wires and the generators are less massive -- a critical point when trying to get off the ground.) |
