GB377671A - Improvements in or relating to electric power supply systems - Google Patents

Abstract

377,671. Supply systems. GENERAL ELECTRIC CO., Ltd. and DAVIS, B., Magnet House, Kingsway, London. April 20, 1931, Nos. 11677 and 31981. [Class 38 (iv).] Supplying consuming devices ; charging batteries; systems depending on static transformers; regulation, automatic.-In a supply system a battery in parallel with the load is trickle-charged from the source supplying the load and automatic voltage regulating means, maintaining a slow rate of charge, is so influenced or excited by current supplied from the battery to the load as to increase the voltage applied to the battery and restrict any discharge so long as the main source is of approximately normal voltage. On failure of the source the battery supplies the load. The regulation may also be influenced by current supplied from the main source to the load. In a system, Fig. 1, supplied through a motor generator 4, 1 a series field winding 3 is connected between the source and the load 7 and between the battery 6 and the load so as to strengthen the field of the generator 1 to maintain the voltage at a value at which the battery will slowly charge notwithstanding increase in load. A part only of the load current may pass through the winding 3. When the battery discharges owing to slow speed of the motor 4, for example, the generator voltage is strengthened so as to restrict this discharge. An additional field winding, normally opposing the winding 3 may carry battery current only so that it may boost the generator voltage on discharge. Reversal of generator polarity is avoided with the arrangements described. The series winding may be replaced by a coil controlling in one or more steps a resistance in the shunt field circuit or in the circuit between generator and battery. One part of this coil may carry only battery current and the other be connected between generator and battery or between battery and load. Fig. 2 shows a system supplied from an A.C. source 11 through a rectifier 12 in which a choking coil 14 in the primary circuit of a transformer has a saturating winding 15, arranged similarly to the regulating windings mentioned above. The winding 15 may control a resistance in the primary circuit of the transformer. In a modification the saturation of the transformer core is varied by the winding 15 which is wound on an additional core limb, or is divided into two similar parts on each of two similar limbs, but connected so as to magnetize them in opposite senses and avoid the generation of A.C. in the said windings. A system is also described in which a three-phase source supplies through transformer windings with a saturable choke in the primary of each phase, two hot cathode rectifiers for full wave rectification, each rectifier having three anodes. The saturating windings are all in series and substantially no A.C. flows in them. In all the A.C. arrangements a choke coil 17 is preferably used in the battery circuit.