GB430010A - Improvements relating to electrical power systems - Google Patents

Abstract

430,010. Equalizing load on generators. PESTARINI, G. M., 4, Tapton House Road, and TUSTIN, A., 22, Glentilt Road, both in Sheffield. Dec. 4, 1933, No. 34065. [Class 38 (iv)] In a constant-voltage supply system a dynamo - electric flywheel or buffer machine 1 is connected across the supply mains 4, 5 and its excitation arrangements include provision of a field 9 varying with the load, and excitation obtained from the secondary circuit of a " metadyne " type machine 7 which is driven from the flywheel shaft so as to make the voltage of the flywheel machine independent of its speed. The flywheel machine 1 may be provided directly with a winding 9 responsive to the load current, and a winding 8 excited from the secondary brushes of a " metadyne " machine 7 on the flywheel shaft, the primary brushes of the " metadyne" machine being connected across the supply mains. A series winding 10 or a resistance may be provided to limit the current in the machine 1. In order to limit the speed of the machine 1, a field winding 12 thereon may be excited from a critically self excited exciter 11 on the flywheel shaft arranged to give a generating torque when the speed exceeds a predetermined value. Alternatively, a minimum generating field may be provided or such field may be increased by a relay responsive to the main field strength or field current of the flywheel machine. At low speeds the metadyne machine saturates and produces a motoring torque in the machine 1. An additional winding responsive to the supply voltage may be provided on the machine 1 opposing the generating torque produced by the winding 9. In a modification, Fig. 7, the flywheel machine itself may be a metadyne machine 16 of which the primary brushes are connected across the supply mains and the secondary brushes are connected together or to a field winding 19 on the metadyne machine. Field windings 17, 18 energized by the supply voltage and load current are provided on the metadyne machine to cooperate with the primary or secondary brush axes. In a further modification the flywheel machine may be ineffective between predetermined limits of load and brought into effect only when these limits are exceeded. This is brought about by providing a winding on the machine directly responsive to load current and an opposing winding supplied from a saturable exciter excited by load current, the two windings being arranged to balance each other within predetermined limits of load. A constantly energized winding makes the machine run at a constant speed within these limits. Alternatively the curve of the saturable exciter may be arranged so that a resultant motoring torque is provided within the limits. The exciter may be driven from the flywheel shaft. Alternatively a single field winding on the flywheel machine may be energized from two exciters in opposed series, their fields being responsive to the load current and one exciter being saturable. In further modifications, where an ordinary dynamo-electric machine is arranged on the flywheel it may be excited from the secondary brushes of a metadyne machine on the same shaft, the primary brushes of such machine being connected to an exciter excited in accordance with the load current and in opposition with a constant field. The same arrangement of exciter may be used in the connection between the secondary brushes of a metadyne machine where this is used as the main flywheel machine. Specifications 404,739, [Group XXXVII], 417,517, and 420,770 are referred to, and the Provisional Specification refers also to Specification 417,381.