GB106008A - Improvements in Electric Conversion. - Google Patents

Abstract

106,008. Cabot, S. June 1, 1916. Commutator switching-arrangements; phase, changing; transformers.-In a system of conversion by polyphase commutation, the polyphase transformer employed has a very small leakage inductance so that the current may be commutated sparklessly with fixed brushes at all loads. An arrangement for converting from polyphase to direct current or vice versa is shown in Figs. 1, 2; one set of transformer windings 33, 34, 35, is connected to three-phase leads, and the other set is connected as a nine-phase winding to the commutator brushes 23 - - 31 supported on fixed bars 21. These brushes rest on the periphery of an insulating disk 16 in which are set four contacts 17 - - 20 each of which subtends an angle of twenty degrees. The contacts 17, 19 are connected to a ring 10, and contacts 18, 20 to a ring 11. The direct current leads are connected to brushes 14, 15 engaging the rings 10. 11. The disk 16 and rings 10, 11 are carried by a shaft rotated by a motor 1, which must be a synchronous motor when the apparatus is used to convert from polyphase to direct current. For converting from direct current to direct current at a different voltage, the windings 33, 34, 35 of the transformer are replaced by a nine-phase winding which is connected to direct current leads through a commutator and slip rings similar to the commutator and slip rings 16, 10. 11. The transformer has a small leakage inductance and is built with a maximum of iron and a minimum of copper, and in winding, the primary sections are sandwiched between the secondary sections. Each core carries the windings of one primary phase and one secondary phase with parts of other secondary phases. In a modification. Figs. 4 and 8, additional disks 42, 42<1> carrv contacts to cause the direct current circuit to be made and broken at a number of points simultaneously. Brushes 60 - - 67 are arranged in pairs over the contacts 51 - - 59, the two brushes of each pair being mounted side by side so that the circuit is comnleted through them as a contact passes under. The connexions also provide for commutating the currents in the transformer winding A B, B C &e. through condensers 76, 76<1>.