GB829420A - Improvements in or relating to a regulating system for a dynamoelectric machine - Google Patents

Abstract

829,420. Magnetic amplifiers. LEECENEVILLE CO. Oct. 18, 1956 [Dec. 8, 1955], No. 31751/56. Class 40 (9). [Also in Group XXXV] In a system for regulating a dynamo-electric machine, the field is energized in accordance with a signal representative of machine loading through a " Ramey " resetting type magnetic amplifier having an inverse transfer characteristic whereby the load current output of the amplifier varies inversely with the control signal, a "Ramey" resetting type magnetic amplifier being one using a core having a substantially rectangular hysteresis loop, and having control and load windings which are alternately energized, wherein the load winding itself effects saturation and the output is determined during the preceding half-cycle by the remanence point to which the core is reset by the input to the control winding. The inverted characteristic is obtained by controlling the amplifier by the additive combination of a reference signal and the control signal and the operation is described in detail with reference to Figs. 3-6 (not shown). The D.C. voltage applied to a load 13, Fig. 7, from an alternator 11 through a rectifier 15 is maintained constant by controlling the alternator field 12 through a full-wave arrangement of magnetic amplifiers of the type described above 23a. Current compensation is provided by a current transformer 27 in one of the phases providing a potential across a resistor 29 in the amplifier input circuit in opposition to the voltage signal, and the reference voltage obtained from winding 60 of transformer 61 (the dots indicating the instantaneous positive potential), is applied with the compensated signal across lines 24a, 25a to the control windings 52, 53. Load windings are fed from winding 70 of the transformer 61 and the resulting output across resistor 76 is applied to a magnetic power amplifier 23b and also of the resetting type in which windings 81, 82 each serve alternately as control and load windings. Cross-connected feedback winding 65, 67, 83, 84 are provided in each of the amplifiers to compensate for the low back-resistance of the rectifiers. A load relay 102 prevents the connection of the load before the alternator has run up to speed and its contacts 105, 106 are closed during this period. A further current transformer 31 is arranged to take over the control when the current exceeds a predetermined limit and when a further alternator 108 is feeding a common load with the alternator 11 desired load sharing is maintained by the opposed outputs from current transformers 110, 114. Resistors 63 and 100 improve the regulation and prevent oscillation respectively, and a temperature-sensitive resistor 38 provides temperature compensation.