Patent GB-257943-A (GB)
Title: Improvements in and relating to regulating systems for dynamo-electric machines
IPC: H02P9/26
Filed: 1926-09-03
Abstract: 257,943. British Thomson-Houston Co., Ltd., (Assignees of Karapetoff, V.). Sept. 3, 1925, [Convention date]. Exciting; dampers and screens. - A synchronous dynamo-electric machine is regulated by applying to its excitation circuits voltages respectively proportional to the sine and cosine of the phase angle between the polar axes of its exciting windings and the point of maximum magneto-motive force produced by the alternating current of the machine, these volt. ages respectively correcting the armature counter and cross magnetic reactions and being derived from a rotary converter and applied to the exciting coils of the synchronous machine through electronic space-current devices. In the method illustrated, the regulating voltages are applied to compensating coils 4, 5, Fig. 2, respectively coaxial with and displaced by 90 electrical degrees from the main exciting coils 3 of the machine. The regulated machine 8, Fig. 1, which may have either a fixed armature or a rotary armature as shown, is separately excited at 3 and drives synchronously a rotary converter 12 having an unwound iron field structure 15 and slip-rings in series relation with the machine 8 through transformers 16. The angularly displaced continuouscurrent brushes 17, 18 and 19, 20 supply the compensating-coils 4, 5 of the machine through thermionic amplifiers 22, 27 controlled by batteries. With no load on the machine 8, the amplifiers are arranged to pass no current to the coils 4, 5. The converter is so connected that the rotations of its armature and the flux are in opposite directions so that the axis of the flux is stationary in space and its displacement from the brushes 17, 18 and 19, 20 corresponds to the phase angle between the polar axes of the windings of the machine 8 and the position of its maximum alternating magneto motive force. Thus, when the brushes are set so that this angle is zero the converter flux is in the direction 17, 18, the voltage between these brushes is zero and that between the brushes 19, 20 is a maximum and the coil 5 gives correct compensation for maximum cross reaction and zero counter reaction. With a phase angle # between the winding axes and point of maximum magnetomotive force the flux shifts through an angle # in the converter and causes compensating currents i sin # and i cos # to flow in the coils 4, 5 via the amplifiers 22, 27. The coils 4, 5 may be so designed as to compensate the armature impedance drop in addition to its reactance and to give also any desired compounding. Damping windings may be provided in the magnet poles at 6, Fig. 2, or the damping may be alternatively obtained by non- magnetic bridges 7, Fig. 3, which support the compensating windings 4. The Specification, as open to inspection under Sect. 91 (3) (a) contains general claims for alternating-current machines regulated by means for producing continuous voltages varying as the sine and cosine of the phase angle between the polar axis of the exciting winding and the maximum value of the load current of the machine. This subject-matter does not appear in the Specification as accepted.