Patent GB-190417423-A (GB)
Title: Improvements in Self-regulating Dynamo Electric Machines
Inventor: ROSENBERG HEINRICH
Filed: 1904-08-10
Granted: 1905-07-13
Abstract: 17,423. Rosenberg, H., and Rosenberg, E. Aug. 10. Dynamos, regulating; motors, controlling.-In a dynamo for train lighting &c., carbide plants, &c., the field magnets and their exciting-circuits are so arranged that a current constant in magnitude and direction is always obtained, although the direction of rotation and speed of the dynamo are variable. The principle of the invention is shown in Fig. 1, in which a dynamo has a main armature A and auxiliary armature a, field windings being provided for each armature. The field winding for the armature a consists of a short winding f<1> through which the whole or a part of the main current from the armature A flows, and an opposing winding f supplied with current from a source Q. The winding F for the armature A is connected directly across the brushes b of the armature a. By these means, if the speed of the dynamo is much increased, or if a short-circuit occurs to increase the output of the machine, the field of the auxiliary machine is weakened by the current in the winding f<1>, whereby the main field is weakened and the output immediately diminished again. If, instead of the series winding f<1>, a shunt winding between the terminals of the main dynamo be used, the voltage of the main machine will be kept within definite limits. The main and subsidiary armatures may be embodied in one, in which case the two fields with their corresponding windings must either be arranged for a different number of of poles, or the magnetic axes of the two fields must be relatively displaced, in order that the two fields may be independent. A four-pole main field and a two-pole auxiliary field are shown in Fig. 3, in which the brushes b bear upon the twopole armature winding, and brushes B are connected with the four-pole armature winding. The four magnet poles have a double winding, the one f supplied by a source Q generating two similar weak poles n above and two poles s below, while a second winding F on each pole is fed from the brushes b, which generates strong poles N, S. The exciting-current may be supplied from the same armature and same commutator as the external current, Fig. 4 showing such an arrangement. In this case, the four poles of a Gramme machine carry different windings, the winding f, fed by a source of current Q, generating two north poles above and two south poles below to resemble a simple two-pole machine. The four-pole field winding is connected between B<1> and B<3>, and is excited with polarities varying with the direction of motion, the main currents now being taken from the middle of a resistance D which short circuits the brushes B<2> , B<4>, and from the point C of the excitation winding F', F', which is distributed in two parts as shown. The exciting- current from the brushes B<1>, B<3> flows in the double windings in the same direction, but the external current which flows from both brushes to the point of supply C flows through the windings in different directions, and therefore, if the two sections of the pole windings be equal, has no effect upon the magnets, but, if they be unequal, then, on the main current rising in value, it can be arranged that the two-pole exciter field is weakened or strengthened to give the desired regulation. The same result may be obtained by employing an auxiliary field at right-angles to the original field, as shown in Fig. 5, where the winding f, fed from a constant source, generates two similar poles n above and the poles s below ; the brushes B<1>, B<3> correspond to this field, these brushes exciting the main field by means of the winding F in the way shown. The same effect can be obtained without a special field winding by making use of armature reactions alone. In this case the armature brushes B<1>, B<3> are short-circuited, and a current flows through the armature which reduces the sum of the field strengths and produces a transverse field N N, S S which lies at right-angles to the original field, the displacement of the field, and therefore the polarity, being dependent upon the direction of rotation, and so the direction of the current produced independent of the direction of rotation. No auxiliary winding is necessary for the automatic regulation in the arrangements shown in Figs. 5 and 6, and in Fig. 5 compounding or overcompounding can be obtained. If the two upper pole-pieces are not separated as in Fig. 6, the machine being built, as shown in Fig. 7, with common pole-pieces P, P, the commutating position is that shown, and commutation poles n, s are used, the arrangement of the poles giving a minimum waste of materials. A three-wire system, in which the voltages are independent of the load, may be arranged, in the form shown in Fig. 6, by connecting the third wire with the short-circuited brushes B<1>, B<3>. The field winding of the exciter may be connected with the brushes which supply the external current, instead of with accumulators as shown, and the whole be made self-exciting. If the machines described be run as motors, they have analogous qualities, but must be started by arranging the machine first as an ordinary motor. Fig. 9 shows the same dynamo, as a compound or compensated dynamo for a three-wire system. Alternating current may be used to produce the magnetic field the direction of which is shifted against the original field, and may be generated by a separate armature winding as shown in Fig. 10, in which W<1> is the short-circuited alternating- current winding, and G is the direct-current winding.