GB760101A - Improvements in electric generators - Google Patents

Abstract

760,101. Exciting dynamo-electric machines. MACFARLANE ENGINEERING CO., Ltd., MACFARLANE, W. I., and MACFARLANE, J. C. Nov. 27, 1952 [Sept. 24, 1951], No. 22300/51. Class 35. A field pole for controlling the output of a D.C. generator comprises saturated and unsaturated parts magnetized in opposite directions by series connected coils, so that at a certain value of excitation the resultant flux is zero, in which the part-poles are bridged by a pole-shoe so that only the resultant flux passes into the armature. In its simplest form, Fig. 1, the pole comprises part-poles 7a, 7b of which the centre part 7b is saturated and the outer parts 7a of larger total cross-section and having air-gaps 9, are unsaturated. In a inodification a single part 7a may be used. Exciting coils wound on the part-poles are arranged so that at a certain current value no resultant flux is produced between the poleshoe 8 and the armature. At greater or smaller currents a resultant flux, of one polarity or the other, is produced to influence the armature. The saturated pole-part may be of retentive material and carry a shading coil. As shown in Fig. 2, the saturated part 7b and unsaturated control part 7a are situated in the core of the field, the resultant of any disturbance appearing as flux through poles 8. The exciting coils 10a and 10b are series connected and the control pole-parts 7a may carry compounding coils 13. A four-pole modification of this construction is described. Specifications 566,168 and 713,633 are referred to.