GB802643A - Improvements in or relating to electric power installations for electric motors - Google Patents

Abstract

802,643. Alternators. SIEMENS-SCHUCKERTWERKE A.G. April 9, 1956 [April 9, 1955], No. 10823/56. Class 35. [Also in Group XXXVII] An electric power installation comprises synchronous generators 2, 3, supplying polechange motors 4 of the induction type having short-circuited rotors and falling torque characteristics. Each motor may be constructed as a double machine, one component of which is capable of operating at four or eight poles, and the other component having thirty-two poles. The exciting windings 6, 7 of the generators are supplied from transformers 9 through rectifiers 8. The transformers have primary windings 11 which are energized in accordance with the generator voltage through chokes 12 and resistors 13. Other primary windings 14 of the transformers 9 are excited in accordance with the output currents of the generators through intermediate transformers 15. Thus, the vectorial sum of a component proportional to the load current and of one proportional to the voltage is formed in each transformer 9, and is then rectified for supply to the field windings 6, 7. In this manner, the voltage of the generators is maintained substantially constant when the induction motors are switched on or have their number of poles changed.