GB421646A - Improvements relating to dynamo electric machines - Google Patents

Abstract

421,646. Alternating - current commutator generators. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London, ADKINS, B., 13, Fisher Avenue, and CLARK, L. J., 49, Sidney Road, both in Paddox, Rugby. June 23, 1933, No. 17948. [Class 35] Exciting.-In order that a polyphase commutator generator, of the type in which the commutator brushes are directly connected to, and the exciting windings are supplied from, the bus-bars, may be made to generate current at frequencies varying from zero to a definite amount, it is provided with two field-windings 6, 7 connected over a rheostat 8 and so arranged that one, 6, gives zero frequency and the other, 7, the maximum frequency required ; to lock the machine at a particular frequency current of that frequency is supplied to the winding 7 from a synchronous generator 10. In the arrangement shown, the machines are driven from a synchronous motor 4 which also drives a continuous - current exciter 5 for the synchronous machines. The brushes 2 of the main generator are connected to a contact arm 9 on the rheostats 8. When the arm 9 is in the position A the frequency is regulated by the winding 7 ; when in the positions B or C by the winding 6 ; in intermediate positions the frequency is between the two. In the position B the resistances in the exciting circuit are unbalanced and the direct current voltage distributions between the brushes is fixed. The exciting circuit of the generator 10 is controlled by a switch 11 which is mechanically connected with the arm 9 so as to be closed when the frequency as regulated by the rheostat 9 is that of the generator 10. The Provisional Specification refers to Specification 420,230.