Three Phase Toroidal Transformer Design Considerations

PLITRON’s 3-Phase Technology™ offers significant benefits over existing 3-Phase transformers (see below)
To 90 kVA

  • Discrete phases or packaged assemblies
  • Packaged versions include flange mount
  • Low quiescent current draw
  • High efficiency


Three-phase power is an efficient method to transmit power from the source to the load, and is used worldwide to distribute power. In a three-phase system, three  3 Phase separate conductors each carrying AC of the same frequency reaches their instantaneous peak vales at 120 degrees apart. This is generally considered a more economical system because less conductor cross-sectional area is required than single-phase circuits. As shown in the waveform diagram, the delay between the phases carries three peak waves each one third of a cycle apart, and has the effect of supplying constant power transfer over each cycle.

There has been little recent advancement in conventional transformer three-phase technology, and much of the installed transformer base is founded on century old constructions. Each phase is wound on a separate core leg, and a common flux return yoke is need per phase.

Standard Three Phase Toroidal Technology


A typical 3 phase toroidal assembly uses three discreet transformers.

The nature of Toroids do not lend for sharing a return magnetic path, thus one approach consists of using three separate single-phase units. Typically all three phases are combined into a mounting assembly. However as each phase is separately accessible, mounting flexibility includes stacking them or installing them side by side.

As power levels increase, toroids can provide more value in multi-phase applications than EI configurations, as toroids use less materials, and relative labour costs can be lower.