Patent GB-277937-A (GB)
Title: Improvements in rectifiers for alternating current
IPC: H01F30/14
Filed: 1927-07-11
Abstract: 277,937. Dubilier Condenser Co. (1925), Ltd., (Assignees of Nyman, A.). Sept. 24, 1926, [Convention date]. Vapour and vacuum or low-pressure apparatus and electrolytic cells, arrangements of; phase, changing; converting pulsating currents into steady continuous currents.-Single-phase alternating current is converted into substantially steady unidirectional current by converting to three-phase current and rectifying. In one arrangement three windings are arranged on the stator of the converter to provide three-phase current which is rectified by a valve having three cathodes co-operating with a common anode. In the arrangement shown in Fig. 3, the primaries of three transformers Ta, Tb, T<c> are supplied with currents differing in phase by 60‹ obtained by feeding the end transformers through a condenser 30 and inductance 31 respectively. The secondaries are connected in reversed relationship through a three-anode valve B so as to supply unidirectional impulses differing in phase by 120‹ through' a smoothing circuit to the output terminals 14. In a modified arrangement, the transformer secondaries are provided with mid-point taps and are associated with six cathodes of a valve having a single anode, the arrangement being such that current impulses corresponding to rectification of six-phase current are supplied to the output terminals. Fig. 8 shows a similar arrangement except that the six-cathode valve is replaced by six valves B<a>, B<b>, B<c> each having a single anode and cathode. In this case, in addition to the usual smoothing arrangement 12, 15. 16, condensers C are connected between the anodes and cathodes, and inductances i are placed in series with each valve. A variable resistance 32 is also provided across the output terminals 14 in order that a constant load may be maintained on the system so that the required phase 14 in order that a constant load may be maintained. According to another arrangement, Fig. 9, a pair of transformers A, C, the primary currents of which are caused to differ in phase by 60‹ by means of a reactance or condenser X, have their secondaries connected together at one end. The common point and the two free ends of the secondaries are connected as shown through three pairs of oppositely-arranged valves B to the output terminals 14 across which a variable resistance 32 for maintaining the required phase relationship is connected. In a further arrangement, two transformers in which the primary currents differ in phase bv 60‹ are provided with multiple secondary windings which are interconnected to produce by phase combination sixphase current, and a rectifying arrangement comprising six valves is employed. The valves employed in the various arrangements described may be of either the vacuum, vapour, or electrolytic type. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the subject-matter of Fig. 1 (Cancelled), in which single-phase current from a source 8 is converted by means of a rotary phase converter Cm having stator windings W, W1 so arranged as to supply currents differing in phases by 90‹ to the primary windings P, P1 of a pair of transformers, the secondaries S, S1 of which are associated with a pair of double-anode valves B1, B2. Cathode heating current is supplied by a transformer T, and the valves are arranged in parallel to supply unidirectional current to output terminals 14 through a smoothing circuit comprising inductance 15 and condensers 12, 16. This subject-matter does not appear in the Specification as accepted.