Patent GB-190523661-A (GB)
Title: Improved Arrangement for the Regulation of Speed of Compensated Single Phase Motors.
Inventor: ARNOLD ENGELBERT
Filed: 1905-11-17
Granted: 1906-12-17
Abstract: 23,661. Arnold, E., and La Cour, J. L. Nov. 21, 1904, [date applied for under Patents Act 1901]. Field magnets; motors, controlling.-Relates to arrangements for regulating the speed of compensated single-phase commutator motors provided with auxiliary field windings connected in series with the armature and situated at right-angles to the line of the short-circuited brushes, as described in Specification No. 10,830, A.D. 1905. Fig. 1 shows a shunt motor provided with three brushes, two of which B1, B2 are short-circuited and the third B3 connected in series with the cross-winding NW. The number of turns of the cross-winding is varied by means of the contact KT. In Fig. 2, the continuous stator winding S serves both as the main and the cross-winding, the series connexion between the cross-winding and the armature being obtained by means of the variable transformer ST. To avoid large wattless currents in regulating the speed by means of the cross-winding, the number of turns of the main field winding, the impressed voltage, or the exciting-voltage for the armature and cross-winding is varied at the same time, or a combination of these methods may be employed. In Fig. 3, the contact KT regulates the speed, the contact KS regulates the tension per turn of the main winding S, while the contact KE regulates the excitation voltage for the circuit of the armature and cross-winding NW. To decrease the speed of the motor, both contacts KE, KS are moved downwards, and may be combined in a single one. In Fig. 4, the variable field windings are replaced by variable transformers. The shunt transformer NT has one coil only, the tension of the main winding S being regulated by means of the contact KS and the excitation voltage by means of the contact KE. The cross-winding NW is fed by means of a variable series transformer ST. The motors may be started by switching the cross and main windings in series, and the direction of rotation is reversed by reversing the excitation voltage. The Specification in the original form as published under the Act of 1901 comprises also the use of induction regulators in place of transformers having sliding contacts, for the purpose of obtaining a continuous regulation of the speed. In Fig. 5, both the main and cross field windings are composed of two parallel parts S1, S2 and NW1, NW2 respectively, and two mechanically-coupled induction regulators NT, ST are employed. The primary winding PW2 of the regulator NT is placed on the movable core, and is connected directly across the motor terminals ; the secondary winding SW2 is connected in series with the main field windings S1, S2, and with the armature. The primary winding PW1 of the regulator ST is arranged in series with the cross-windings, and the secondary winding SW1 in series with the armature. The movable cores of both induction regulators are provided with closed-circuit compensating-coils KW1, KW2. The induction regulators are preferably used only for the finer speed adjustments, wider variations being obtained by altering the grouping of the field windings, or the voltage impressed upon the stator terminals. For example, when both regulators have been turned through 90 degrees, the connexions of the windings S1, S2 and NW1, NW2 are changed from parallel to series. At the same time, the leads to PW1, PW2 are reversed, so that the electromotive forces in SW1, SW2 are reversed and are added to the voltage which they had previously opposed, and vice versa, the induction regulators being then adjusted as before.