GB226233A - Alternating/direct current converter with wide voltage regulation - Google Patents

Abstract

226,233. La Cour, J. L. Dec. 15, 1923, [Convention date.]. Systems depending on the use of static transformers.-The direct-current voltage of a rotary converter R is varied in the ratio of about 4 : 1 by employing on the alternating-current side a voltage regulator with a 2 : 1 ratio the direct current leads LN being connected either across the brushes B<1>, B<2> of the converter, or between one of the brushes B' and the neutral point O. In the arrangement shown, three-phase mains TN are connected to an auto-transformer comprising windings V<1> - - V<3> and W<1> - - W<3>. The two windings in each phase, e.g. V<1>, W<1> have approximately the same number of turns and are wound on the same core. The slip rings S' - - S<3> of the converter are connected to contact-arms k<1> - - k<3> moving over the windings W<1> - - W<3>. By moving these contact-arms from the outer to the inner ends of the windings, the voltage supplied to the slip rings is reduced in the ratio 4:2. To obtain a further reduction in the ratio 2:1, the direct-current circuit is momentarily opened by a switch u coupled to the contact-arms, the contact-arms are then moved to the outer ends of the windings, and the switch u is thrown over to connect one of the direct-current lines to the neutral point O. These operations, which are performed nearly simultaneously, produce no change in the directcurrent voltage, but the latter can now be further reduced ir. the ratio 2 : 1 by again moving the contact arms K<1>, - - K<3> over the windings. In a modified arrangement an induction regulator with rotatable secondary windings connected to the slip rings, is employed. By moving the rotor of the induction regulator through 180‹, voltage regulation in the ratio 4 : 2 is obtained. At this point, a controller reverses the secondary windings and connects one of the direct-current lines to the neutral point, whereupon further rotation of the rotor through 180‹ produces an additional voltage regulation in the ratio 2 : 1. The induction regulator may be constructed partly as an auto-transformer, the reversing switches being connected to tappings on the primary windings.