Patent GB-190308831-A (GB)
Title: Improvements in the Compounding of Synchronous Alternators for Single and Polyphase Electric Currents.
Inventor: HEYLAND ALEXANDER
Filed: 1903-04-18
Granted: 1904-03-24
Abstract: 8831. Heyland, A. April 18. Dynamos, regulating; motors, controlling.- Synchronous alternators are compounded so that the main current, or a current proportional to it, is decomposed into its watt and wattless components, by connecting the pole winding to a commutator so that two groups of circuits differing between themselves by a quarter of a period are formed. The brushes are arranged so that the wattless component traverses the pole windings in a constant direction, while the watt component traverses circuits that differ by a quarter of a period from the pole winding, or traverses parts of the pole winding in opposite directions so that it exerts no magnetizing effect. Fig. 1 shows an arrangement for a two-phase machine. The pole winding is divided into sections a, b, c, d arranged in series between the commutator segments 1, 5, and connected by conductors x, x<1>, y, y<1>, z, z<1> to the segments 8, 2, 7, 3, 6, 4 respectively. Four brushes are used. Supposing that the brushes and inducing part revolve, and the poles and commutator are stationary, the watt and wattless currents then flow respectively in horizontal and vertical directions. In the position of the brushes shown in Fig. 1, the wattless current flows from the brush I to the brush III through the pole windings a, b, c, d, and the watt current flows from the brush II to the brush IV through the connections y, y<1>. After one-eighth of a revolution the wattless current flows from the segments 2, 8 to the segments 4, 6 respectively, passing through the windings b, c, and the watt current flows through the conductors x<1>, x and z<1>, z. In a modification, the pole winding is subdivided into sections arranged in parallel and connected by conductors, as shown in Fig. 3. The action is similar to the first arrangement. Fig. 3 shows one arrangement of the brush connections. The stator has phase windings A, B connected as shown to the brushes. On rotating the commutator and rotor, the current is decomposed as explained above. Assuming the field to be excited from outside, then, when the winding axis is vertical, the electromotive force of the phase B is at a maximum, while that of the phase A is zero. Hence, if there is no lag or lead, the current produced has no effect on the pole winding, but, if there is a lag or lead, the wattless component traverses the axis of the pole windings and strengthens the field. The poles may have separate windings for the exciting-current and the wattless current. Instead of compounding the poles of the alternator, the poles of the direct-current dynamo producing the exciting-current may be compounded. It is also desirable to wind the subdivisions of the pole winding in parallel as described in Specification No. 16,205, A.D. 1902, to avoid pulsations. This commutator can also be applied for exciting the alternator, the usual exciter being dispensed with. In this case, the compounding-connection described in Specification No. 25,221, A.D. 1901, is used. These commutators are applicable to synchronous or asynchronous machines. In a modification, the rotating part is the inducing-armature, while the stationary part constitutes the poles, the brushes being connected to the pole winding. As in this case the brushes and commutator exchange their usual functions, the brushes and commutator segments are replaced respectively by commutator segments and brushes. The rotating part may have ordinary poles, but, if intended for use on a motor, it is given a circular form similar to the rotor of an asynchronous motor. It receives as exciting or compounding winding only a singlephase winding, which serves as a starting-winding. Such a motor exerts a powerful torque like a three-phase asynchronous motor in which one phase winding is cut out, and the rotor winding is short-circuited over two contact-rings only. A second winding may be employed for starting the machine until synchronous running is obtained.