Improved Arrangements for Obtaining Sparkless Commutation in Rotary Converters Coupled to Alternating Current Boosters.

摘要

23,285. Siemens-Schuckertwerke. Nov. 14, 1911, [Convention date]. Rotary converters.- The commutating windings of a rotary converter, which is coupled mechanically to a synchronous alternating- current booster, a r e excited by a current dependant u p o n the output of the booster as well as by the continuous current of the converter. In the form shown in Fig. 1, the commutating - poles of the converter u a r e excited by the ordinary continuous-current winding wand by another winding w1 connected to auxiliary brushes placed midway between the main converter brushes or at any other position such that they take a current proportional to the alternating-current passing through the booster z. Alternatively, as shown in Fig. 3, the auxiliary winding w1 is excited from a commutator k which is connected either to the armature windings of the booster z or to a special winding on the booster. The booster has auxiliary poles, the winding s of which carries the whole or part of the converter current, and auxiliary brushes b, from which the auxiliary coils w1 on the converter commutating-poles are excited; v is the winding of the booster main poles. The booster auxiliary poles oppose the armature flux so that the current in the coils w1 is proportional to the difference between the load current in the booster and the continuous current of the converter. The auxiliary voltage may be applied directly to the main commutating-windings w instead of to separate coils w1. Alternatively, the coils w1 may be excited from a separate machine coupled with the converter set and having the alternating converter current in its armature and the continuous current in its field coils. In the arrangement shown in Fig. 5, the auxiliary coils w1 on the commutating-poles of the converter are excited by a machine h which is excited by the main continuous current at g and is driven by a motor m, of which the field f1 is constantly excited and the armature of which is connected in parallel with the field coils v of the booster z. The speed of the machine h being nearly proportional to the booster voltage, the excitation of the windings w1 is approximately proportional to the booster load. The motor m may be a compensated commutator motor fed from the alternating-current side, or the machines h, m may be combined into a single machine having one armature with two commutators and fields of different pole numbers.