Patent GB-506336-A (GB)
Title: Improvements relating to alternating current voltage regulators
IPC: H01F29/10
Filed: 1937-11-17
Abstract: 506,336. Transformers. HANSELL. J. R., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Nov. 17, 1937, Nos. 31660/37 and 31279/38. [Class 38 (ii)] In it voltage regulating transformer the primary winding is subdivided and the parts mounted on a core structure shaped to form a separate magnetic circuit for each part and provided with a movable magnetic member whereby the distribution of voltage across the parts is adjusted, and the secondary winding is in two or more parts which are closely associated with the primary winding and arranged so that opposed voltages are produced in the secondary circuit. In the form shown in Fig. 1. the primary and secondary windings are each divided into two parts and mounted in stots A, B of a core 1, 2 having a movable magnetic member 13 to effect variation of the impedances of the winding parts. In its upper position the impedance of the winding parts in the slot A is a maximum, and in its lower position the impedance of the winding parts in the slot B is a maximum. The reversely connected secondary winding parts enables regulation of the voltage from one maximum, through zero to its maximum with the phase reversed to be obtained. Using an autotransformer connection, a boosting transformer giving buck and boost is obtained. In the form shown in Fig. 6, the secondary circuit 107, 108 is connected to the line 103 and to the centre point 110 of the primary circuit through the secondary winding parts 105, 106. By this means the voltage may be regulated from a value above the maximum across the primary winding part 101, through zero to a negative value. The winding 105 may be provided with only sufficient turns to compensate the effect on the output voltage of the reactance of the winding 102 so that the secondary voltage is adjustable up to the value of the supply voltage. Similarly, the winding 106 may be provided with only sufficient turns to compensate the reactance of the winding 101 to enable the secondary voltage to be reduced to zero. The movable core 13, Fig. 1, is cut away to increase the air-gaps 5 so that in the central position the individual reactances of the secondary windings are reduced. The core is mounted in a slide and may be adjusted by means of a nut 18 engaging a threaded rod 26 which may be calibrated. A three-phase booster system is shown in Fig. 8, in which the core parts 1, 2 are provided with six slots to accommodate the windings which are connected in delta on the primary side, movable cores 13A, 13B, 13C being linked together for simultaneous movement. In a further modification, the windings are arranged in V-connection. This permits a core having four slots and two movable cores to be used. In a further modification, a 3-phase arrangement is described having a similar core system but in which the windings are connected in T-formation. Fig. 13 shows an arrangement in which the windings are in T-connection but in which to obtain a stationary neutral N, Fig. 14, components BQ, CQ in phase with OA, and obtained from windings 132, 133 and 135, 136 are included in the phases OB, OC. In this arrangement three neutral connections 137 are provided by subdividing the main windings 120, 121.