A choke coil for preventing harmonic distortions having a plurality of laminated iron core sheets formed into a core. A first coil is wound around a first limb of a first core, and a second coil is wound around a first limb of a second core. A third coil is wound around the second limb of both the first...http://www.google.es/patents/US6014071?utm_source=gb-gplus-sharePatente US6014071 - Choke coil
