Patent GB-190716781-A (GB)
Title: An Improved Method of Regulating the Electric Potential of a Network Supplied by a Generator Driven at very Variable Speeds, and Apparatus therefor.
Inventor: SCHALLER OTTO
Filed: 1907-07-22
Granted: 1908-08-24
Abstract: 16,781. Schaller, O. Aug. 11, 1906, [date applied for under Patents Act, 1901]. Armatures; dynamos and motors combined for transmitting power; dynamos, regulating.-E l e ct t r i instaUations fed from a variable-speed generator have the network voltage maintained at practically constant value by the following means. As shown in Fig. 1, an auxiliary dynamo M' is placed on the variable-speed shaft W<1> and its electromotive force combined with a source of constant potential, for example a battery B. The resultant electromotive force, which varies step for step but oppositely to the' electromotive force of the main generator D<1>, is used to drive a second shaft W, on which is a third generator D<2>, by means of a motor M<2>. Hence the electromotive force of the dynamo D<2> falls as the main dynamo D' rises, and the sum of their electromotive forces is constant under suitable conditions of excitation. The two armatures A', A<2> of the dynamos D<1>, D<2> are coupled in series with each other and with the load. The fields of the motor M<2> and the dynamo M' are in series, as also are the fields of the dynamos D<1>, D<2>, both circuits being fed by the constant potential source B or by the steady netting voltage, The excitation of the fields may be modified by currents obtained from either of the machines, to obtain various voltage or speed alterations. The armatures A', a' of the machines D', M' may be placed in a common field, as may also the armatures A<2>, a<2> of the machines D<2>, M<2>, Fig. 2. Fig. 3 shows a modified arrangement, in which the field magnet F of the main dynamo and the armature a' of the first auxiliary generator M' are placed on the variable speed shaft W<1>, and the armature A of the main generator is driven by the motor M' supplied, as before, by the resultant voltage of the armature a<1> and the constant potential source B. The connexions are such that relative speed between the armature A and field F is kept constant. The armature A may be driven by the shaft W<1>, while the field F is driven by the motor M<2>. Slip rings are needed for the field F in these two arrangements. Fig. 4 shows the scheme of connexions, the field F and the fields f<1>, f<2> of the machines M<1>, M<2> being excited in series from the constantpotential source B. This Figure also shows a method of affecting the regulation by increasing the excitation of the motor M<2> with an increase in speed of the shaft W<1> (or armature a<1>). By similar means, the voltage in the load circuit may be made to rise, fall, or remain constant with variation of load. The dynamo D may be worked as an alternate-current machine. Fig. 5 shows another arrangement, in which the armatures a, a' have been combined into a single armature, and placed with the main armature A on a common core. The core is arranged to rotate freely around the variable-speed shaft W', on which is placed the field-magnet F of the main dynamo, the connexions remaining as before. The winding corresponding to the armature A of Figs. 3 and 4 is connected to the load and gives a steady electromotive force.