Volume and weight
The toroidal core has the optimal shape for producing a transformer with the minimum of material. Because the quality of the core is such a vital consideration for sensitive applications, Talema has invested heavily to provide extensive core manufacturing, annealing and testing facilities.
All windings are symmetrically spread over the entire core which makes the wire length very short. A higher flux density is possible as the magnetic flux is in the same direction as the rolling direction of the grain orientated core allowing significant savings of volume and weight. A higher current density can flow through the wire as the whole surface of the toroidal core allows efficient cooling of the copper windings.
The iron losses of the toroidal core are very small, typically 1.1W/kg at 1.7Tesla and 50Hz, giving very small magnetizing current, which contributes to the excellent temperature rating of the toroidal transformer.