O-core is a new type transformer core after EI core, C-core, Toroidal core and R-core. It is wound from Grain Oriented silicon steels with low iron loss and high flux density, which is slit into curve strips by computer-controlled slitting machine. The external shape of O-core is round or oval, which is similar to that of toroidal core, but its cross-section is round which is similar to that of R-core. Therefore, O-core combines advantages of both toroidal core and R-core. Having a round cross-section, it is very convenient to make windings on O-core, the layout of windings is smooth and tight, which reduce the vibration dramatically. At the same time, the length each turn is reduced by about 10%, total copper wire and insulation material can be reduced by 13-30%. It doesn抰 need bobbins to make windings, and there are more choices in wire diameter. The round cross-section improves electric performance of the core. The tight windings and the fact of no shape angles provide a well-distributed magnetic field. The improved coupling reduce magnetic leakage. The impedance is reduced accordingly as the length of each turn is reduced. The over load capacity improved consequently. Similar to R-core, O-core is wound from one continuous silicon steel strip and there are no joints, so the problem of humming can be solved radically. O-core has superior quality to toroidal core and has lower cost than R-core. As an patent product, it provides a better choice for transformer users. Specifications: O-core may be supplied: 1. Impregnated 2. Epoxy coated O-core types: 1. OA type (round cross section ） 2. OB type (oval cross section) Applications: Power transformer, current transducer, instrument transformer, inductor, ballast, AF transformer, magnetic amplifier, voltage stabilizer and regulator, special transformer etc Minimum power: 8VA Maximum power: 3000VA