focus on the various types of three-phase transformers that
support this type of power system. By nature, three phase
transformers are designed with three primary windings and three
secondary windings mounted on a three-legged core.
in several ways. The primaries may be connected in a delta
configuration and the secondaries in a wye configuration or visa
offers greater advantages to the over-all system performance. As
such, most power and distribution transformers are constructed
using the same connections.
to form the neutral. In most power systems, the neutral is grounded,
providing a low resistance connection to earth and an electrical
reference point at zero points. By having this reference point,
safety, voltage stability and protection system design are
suitable for a specific application, the following criteria could be
to-Line connections (L-L)
result in a significant of current on the neutral
the original output
it more versatile.
windings connected the same (delta-delta or wye-wye), or differently
(delta-wye or wye-delta). It is important to note that the secondary
voltage waveforms will be in phase with the primary waveforms
when the primary and secondary windings are connected the same
connected differently, the secondary voltage waveforms will differ
from the corresponding primary voltage waveforms by 30 electrical
in parallel, and their phase shifts are not identical, a short circuit will
occur when the transformers are energized.
the size of the transformer you need to determine the following
(volts x amps x 1.732) / 1000 = kVA
to the kVA resulting from the above equation.