GB636454A - Improvements relating to the regulation of alternators - Google Patents

Abstract

636,454. Automatic control systems. STONE & CO., Ltd., J., and CHAPMAN, E. E. Aug. 1, 1946, No. 3243. [Class 38 (iv)] In an arrangement for regulating alternators, having an electromagnetically actuated moving system, such as a carbon pile regulator, the regulator is inherently astatic and is influenced by currents proportional to the voltage and also the load current of the alternator which tend to produce a static voltage/load characteristic which characteristic is corrected to provide a constant voltage output at a given power factor by introducing a third current which is dependent upon the power factor of the load current. The characteristics of static and astatic regulators are discussed. The arrangement is especially applicable to systems of alternators connected in parallel. In Fig. 1, the main winding W of a carbon pile regulator is connected between two of the three lines A, B, C from the alternator through a rectifying bridge D1. A transformer T1 connected in line C applies an additional rectified current through bridge D2 to winding W, which is proportional to the load current. In order to avoid the resulting droop of the alternator load characteristic, an additional transformer T2 is used to supply a voltage which depends on the power factor, to the A.C. side of bridge D1. The variable resistors R1, R2 and R3 are adjusted to provide a constant voltage characteristic at a given power factor, and the arrangement is then such that a rising (or falling) characteristic is provided at other power factors by the action of the regulator. When applied to a number of alternators connected in parallel, the arrangement provides for the various power factors to be equal. Alternative arrangements in which bridge D2 is arranged to supply an additional coil for the regulator, or for both voltages to be obtained from one transformer are also described. In the case of single phase alternators, or two phase three-wire alternators, phase adjusting means may be provided in the transformer secondary circuit.