Patent GB-191312578-A (GB)
Title: Improvements in or relating to Electrical Regulating Systems for Variable-speed Dynamos.
Inventor: MELLERSH-JACKSON WILLIAM JOHN
IPC: H02J7/20
Filed: 1913-05-29
Granted: 1914-06-29
Abstract: 12,578. Jackson, W. J. Mellersh-, [United States Light and Heating Co.]. May 29. Dynamos, regulating.-Relates to the regulation of variable-speed shunt-wound generators such as are employed, in conjunction with storage batteries, in car-lighting systems. In addition to regulating for constant current during charging, by introducing an automatically varying resistance in the shunt-field circuit, a further regulation for constant voltage is obtained after the battery is fully charged, by introducing a second variable resistance in parallel with the shunt field. This latter resistance is arranged so that it diminishes in value as the voltage of the generator tends to increase, thus diverting more current from, and consequently weakening, the field. The resistances employed are preferably carbon or like compressible rheostats. In the arrangement shown in Fig. 1, the generator 1, on being started, builds up the voltage until the coil 17 closes the switch 14 to connect the generator to the battery 15. During the charging of the battery, the series coils 4, acting through the lever 5 on the compressible rheostat 3 in series with the shunt field 2, regulates the current output. When the battery is fully charged, the voltage coil 9 raises the core 8 and breaks between the contacts 11, 12 the shunt circuit 23 around the fixed resistance 10 in series with the field 2; at the same time, the core 8 raises the second carbon rheostat 7 against the contact 13, and so completes a circuit 23, 13, 24, 25 in parallel with the shunt field. By the insertion of the resistance 10 and the action of the coil 9 on the rheostat 7, the voltage of the generator is thereafter regulated, at a value which is below the fully-charged voltage of the battery and equivalent to the voltage at which the battery floats on the line. In a modification, the core 8 acts on the rheostat 7 through a bell-crank lever similar to the lever 5; the lever is also connected to the lead 23 and carries the contact 11, thus dispensing with the contact 13. In the modification shown in Fig. 4, the core of a relay coil 34, which replaces the coil 9, operates two armatures 35, 29, the former acting on the rheostat 7, and the latter when attracted breaking at the contact 31 the shunt circuit around the resistance 10, and completing at the contact 33 the circuit 23, 33, 7, 25 in parallel with the field 2. Figs. 5 and 6 show the construction of the relay. The coil 34 is wound on two cores 38, which are bevelled at their upper ends and co-operate with the wedgeshaped armature 35 on the lever 36, thus giving increased attraction, as the armature moves downwards, to compensate for the increasing counter-pressure of the rheostat. The air-gap between the armature 35 and the pole-pieces 38 is made so great that the armature is not attracted by the coils 34 until the armature 39 on the lower lever 29 has been attracted so as to close the air-gap between itself and the cores. In another modification of Fig. 1, the coil 9 is replaced by two coils in series, one acting on the rheostat 7 and the other actuating an armature analogous to the armature 29, Fig. 4.