Patent GB-571031-A (GB)
Title: Means for connecting loads to polyphase networks alternatively in different phase sequence
IPC: H02P27/02
Filed: 1943-08-19
Abstract: 571,031. Control systems for polyphase consumption apparatus; control of A.C. motors; automatic control systems. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. Aug. 19, 1943, No. 13512. Convention date, Aug. 29, 1942. [Class 38 (iv)] [Also in Group XXXVII] Switching control ; control of voltage and variables in general.-The phase sequence connection of a load to a polyphase network is determined by the selective saturatiori of transductors in the phase connections, the transductors being oppositely polarized so as to react directly in accordance with the sense and value of an electric directing quantity. The polarization may be determined by rectifiers in series with self-saturating windings or in series with saturating windings energized by the directing quantity. Fig. 1 shows a polyphase motor which may actuate a regulating transformer controlling the voltage in accordance with a directing current proportional to that voltage. This current is applied to saturating windings 222, 232 which are opposed by saturating windings 221, 231 fed with a constant comparison current. Self-saturating or reaction windings 223, 233 are connected in series with the main windings 22, 23 of the transductors through rectifiers respectively poled in opposite senses. According to the sense of the directing current, one or other of the transductors becomes completely saturated. The windings 22, 23 are connected between one terminal 12 of the motor 10 and different phases 2, 3 of the polyphase network. Similarly, windings 32, 33 of other transductors are connected between the terminal 13 and the phases 2, 3, the terminal 11 being connected to phase 1. The windings 32, 33 have saturating windings arranged similarly to like windings on transductors 22, 23, but the control windings 332, 322 are connected in series with the selfsaturating windings 223, 233 respectively. The motor is accordingly energized in alternative phase sequence according to the sense of the control current. A brake release magnet for the motor is energized through a transductor having a self-saturating winding and control windings 152, 153 alternatively energized by the self-saturating current of the transductors 32 and 33 respectively. Fig. 2 shows an alternative in which the control windings of transductors 212, 412 are connected in parallel in the control circuit through oppositely poled rectifiers. Two terminals of the motor are connected respectively to phases 1 and 3 of the network, transductor 212 is connected between phase 2 and the third terminal of the motor and transductor 412 between that terminal and an artificial pole 4 constituted by means of one auxiliary transformer to produce an opposed phase sequence. To prevent single phasing, a transductor 111 may be saturated by a winding 112 in the control circuit. In a further arrangement, Fig. 3 (not shown), two asynchronous motors acting oppositely upon a regulator are connected in opposite phase sequence to the networks, each through three transductor windings on separate core legs. The saturating control windings of each set are in a separate series circuit including a rectifier (blanking valve). The rectifiers are oppositely poled and the series circuits are in parallel in the control circuit.