Patent GB-190409831-A (GB)
Title: Improved Means for the Regulation of Electric Circuits for the Production of Constant Current, or Constant Potential, or of both.
Inventor: JAMES REGINALD WILLIAM
Filed: 1904-04-29
Granted: 1905-01-12
Abstract: 9831. James, R. W., [Northern Electric Co.]. April 29. Dynamos, regulating.-Relates to regulating - means for electric currents for producing either constant current or constant potential in separate systems, or both in different parts of one system supplied by one or more generators. The invention is particularly applicable to car or other lighting-systems supplied by a secondary battery in shunt with a dynamo having a variable speed. The system may be arranged to diminish the charging-current as the battery approaches its full charge. A resistance is used in which increase of pressure on its ends decreases the resistance. In the constantcurrent arrangement shown in Fig. 1, the main circuit 4 of a shunt-wound dynamo 1 includes translating-devices 6, part of the coil of an electromagnet 7, and the usual circuit-closing solenoid 21. A resistance 13, connected in series with the fieldmagnet coils 3 across the brushes, is such that an increase of pressure on its ends reduces its resistance. It is operated by a lever 11, pivoted at 12, pressed by a spring 10 so as to compress the resistance 13, and connected to the core 9 of the electromagnet 7. The remainder of the coils of the magnet 7 are connected in shunt with the resistance 13. A battery 5 is arranged in parallel with the translating-devices 6. On an increase of current in the circuit 4, the armature 9 is lifted so as to decrease the pressure on the column 13, and increase its resistance. Additional current then passes through the other part of the coil 7, acting to raise the resistance further, and reduce the current in the coils 3, until finally a state of equilibrium is reached when the current in the circuit 4 is the same as before. By suitably proportioning the auxiliary part of the coil 7, the device can be made very sensitive. In a modification, the wire 16 of this auxiliary part is connected directly to the negative brush so as to act against the other part of the coil 7. As the resistance increases, the auxiliary coil takes less current, and a similar result is produced. Fig. 3 shows a modification, in which the core 9 is held by a weight 22 or by a spring out of action until the current rises to a predetermined strength. The plates of the column 13 are pressed together by a yoke 24 controlled by a spring 27, and mounted on a rod secured by a set-screw in a swivelling bracket. The series circuit of the solenoid 7 is connected to terminals 32, 33 adapted to be connected, when the core 9 rises, by a bridge 35 carried by a rod which slides in the pole-piece 34a of the solenoid 7. The ends of the parts 9, 34<a> are made conical, as shown, to lessen the magnetic effect of the approach of the core and pole-piece. Fig. 5 shows an arrangement for producing constant current and constant potential. A resistance of the form shown in Fig. 3 is controlled by a solenoid having coils 7<a>, 7<b>, 7<c> arranged, respectively, in the main circuit 4, between the negative brush and a point 38, and in shunt with the resistance 13. The coil 7<b> serves to raise the core 9 and close the main circuit 4 through the coil 7<a>, and to exert a constant lifting tendency on the core 9. This tendency is increased by a battery 5. Translating-devices designed to work at constant potential are arranged in a circuit 4<a> passing through a resistance 46, which is compressed by a lever 47 pressed by a spring 48. The spring 48 is resisted by an electromagnet 40 arranged in shunt with the translating-devices 6, and having a polepiece 41 adapted to attract a lever 42 pivoted to a sliding rod 44 which engages the lever 47. A spring 45 holds the rod 44 out of action until a predetermined strength of current is reached. The main switch 50 is arranged as shown.