Ferrite toroidal cores are used at higher frequencies, typically between a few tens of kilohertz to hundreds of megahertz, to reduce losses, physical size, and weight of inductive components.
12.
Unlike a split core ( a core made of two elements, like a pair of " E " cores ), specialized machinery is required for automated winding of a toroidal core.
13.
Because of their symmetry, toroidal cores allow a minimum of the magnetic flux to escape outside the core ( called " leakage flux " ), so they radiate less electromagnetic interference than other shapes.
14.
Toroidal cores are used despite the high manufacturing costs ( a great deal of manual work ) due to the low magnetic flux leakage ( MFL Leakage inductance ), low core losses and the good power density.
15.
Relatively few toroids are offered with power ratings above 10 kVA, and practically none above 25 kVA . Small distribution transformers may achieve some of the benefits of a toroidal core by splitting it and forcing it open, then inserting a bobbin containing primary and secondary windings.
