GB840265A - Improvements in or relating to compounded single-phase or polyphase alternating current generators - Google Patents

Abstract

840,265. Alternators; converting. KELLMA A.B. Oct. 17, 1957 [Oct. 31, 1956], No. 32469/57. Classes 35 and 38 (2). A single or polyphase alternator is compound excited by means of a resistance or inductance divider connected to a rectifying commutator connected to the alternator shaft. The divider has a number of equal inductances or resistances equal to half the number of segments per phase of the commutator, the segments being connected in opposite pairs to the divider terminals, and each phase-group of segments being connected to a separate divider. As shown for a single-phase alternator, the rotor winding 3 is energized from a pair of brushes 8 rotating over commutator segments 6 connected to the stator windings 2, 11 and to a resistance divider 5. Except for the segments at either side which are connected to the ends of the divider, the segments are joined in pairs by equalizing connections 10. The terminals of the divider are connected to contacts 12 which may be selectively engaged by pairs of contacts 15, 16 so that the machine load current and a voltage component may be caused to pass through part or all of the divider to produce any desired compounding effect. The coil 11 which provides the no-load voltage component is offset from the centre of the winding to provide greater variation of voltage control. It is described how the principle may be applied to alternators having a greater number of poles or phases. A transformer may be interposed between the alternator and divider. Specification 783,686 is referred to.