GB391930A - Improvements in or relating to dynamo-electric generators - Google Patents

Abstract

391,930. Dynamos; transformers. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Bergman, S. R.; 171, Willow Road, Nahant, Massachusetts, U.S.A.) Feb. 8, 1932, No. 3725. Convention date, Feb. 7, 1931. [Classes 35 and 38 (ii).] Exciting.-The field and armature circuits of a generator supplying a fluctuating load, for example, a welding arc 27, 28, are coupled together by an external magnetic coupling the effect of which is opposite to that between the circuits in the machine, the coupling comprising a primary winding 17 in series with the armature circuit, a secondary winding 18 in series with a field winding and a magnetic core structure for the windings having two magnetic circuits 19, 20 with air gaps 21, 22 in each circuit, the circuit 19 being common to both primary and secondary windings and carrying the main flux, and the other magnetic circuit 20 providing a leakage flux path about the primary winding. The generator is of the type described in Specification 159,374, [Class 35, Dynamoelectric generators &c.], and comprises a twopole armature 1 rotating in a four-pole field. Adjacent field poles 2, 3 and 4, 5 are of the same polarity. Field coils 9, 10 on the poles 3, 5 are connected across a main brush 6 and an auxiliary brush 8 and coils 11, 12 on the remaining poles are connected across the same brushes in series with a rheostat 15 and the transformer winding 18. The poles 3, 5 are substantially saturated so that the component RM of the armature reaction which acts in the same direction as the main field #M has no effect on the constancy of the field. The poles 2, 4 are unsaturated and the component RC of the armature reaction opposes the cross field #C so that the flux in these poles is variable. The poles 2, 4 may have tapped series opposing windings 13 and commutating poles 16 may be provided. The magnetic coupling described also furnishes the necessary series stabilizing reactance.