Toroidal and Rectangular Magnetic Cores

YUKON RU LLC manufactures toroidal and rectangular magnetic cores for transformers and chokes from various grades of grain-oriented electrical steel, with thicknesses of 0.08–0.3 mm and widths of 8–50 mm. Toroidal cores with a height (h) exceeding 50 mm are assembled from two or more cores. The maximum outer diameter (D) of a magnetic core is 420 mm.

Toroidal magnetic cores are wound on a wide range of mandrels. Cores with custom inner and outer diameters (d and D) can be manufactured after the necessary tooling has been designed and produced.

The company also has tooling for winding rectangular magnetic cores. In some applications, rectangular wound cores offer performance comparable to toroidal cores and are used, for example, in current transformers requiring a large internal window.

Advantages of transformers with toroidal cores

Higher efficiency of toroidal transformers is achieved through extremely low losses in the toroidal core. Typical losses are 1.05–1.2 W/kg at a magnetic flux density of 1.7 T and a frequency of 50/60 Hz. This results in a very low magnetizing current, contributing to the transformer’s excellent thermal load capacity.

The higher magnetic flux density of wound toroidal cores is made possible by the use of high-quality electrical steel, the uniformity of the magnetic path with no air gaps, and the alignment of the magnetic flux with the rolling direction of the steel strip, where its magnetic permeability is highest.

The ability to distribute the windings evenly over the entire surface of the core also significantly reduces leakage losses and lowers the winding resistance by shortening the required wire length, thereby increasing overall efficiency.

“text-align: left;”>Smaller volume and weight are due to the ideal ring shape of the toroidal core, which allows the minimum amount of material to be used while maintaining high magnetic permeability. This is achieved through more efficient use of the entire core volume compared with other types of cores. Optimal winding design and efficient placement of the windings over the entire surface of the core also reduce the required wire length, resulting in smaller dimensions and lower weight.

Energy Savings Energy savings from operating transformers with toroidal cores can reach 86% at no load and 36% under load. Considering the importance of a transformer’s initial purchase cost, however, this is far from the whole picture. Global recognition that energy production affects the environment has led to a continuing rise in energy prices.

Using toroidal transformers instead of conventional transformers with laminated cores made from separate steel sheets provides significant electricity savings. The additional cost of purchasing toroidal transformers is typically recovered through energy savings within two to three years of operation.

Dimensional Flexibility The advantages of toroidal transformers over conventional laminated-core transformers are achieved through the use of toroidal cores manufactured in-house using high-quality electric annealing furnaces. This enables us to produce high-quality cores of virtually any diameter and height. Our specialists can custom-design a toroidal transformer to fit precisely into a confined space, which is generally impossible with conventional transformers.

Simple and quick installation Transformers rated up to 1 kVA and built with toroidal cores are mounted using one centering plastic washer—or two, one above and one below—or a metal washer with a protective rubber gasket, together with a mounting bolt passing through the transformer’s central opening.

Low magnetic leakage is often an important criterion when selecting a transformer for designers of electronic equipment sensitive to external electromagnetic fields, as the transformer itself can become a source of such fields. Toroidal transformers manufactured by YUKON RU LLC have 85–95% less magnetic leakage than conventional transformers. This low leakage is achieved by distributing the winding evenly over the entire surface of the toroidal core.