GB119081A - Improvements in or relating to the Rectification of Alternating Currents of Electricity. - Google Patents

Abstract

119,081. Pollock, S. A. Sept. 19, 1917. Commutator switching-arrangements. - Alternating currents are rectified by means of a relay, with a polarized armature moving from one position to the other as the flux reverses, the relay having a winding carrying the supply voltage and other windings carrying the whole or part of the load current. The primary of the transformer P is connected to the alternating current supply, and the halves of the secondary winding are used alternately to supply the rectified load circuit which in this case consists of a battery O. The rectifying relay A has an oscillating tongue c<1> polarized by an electro-magnet or by a permanent magnet p<1>. A voltage winding d is connected in series with a condenser k across the transformer secondary, and the condenser capacity is adjusted so that the reversal of motion of the tongue c' occurs when the current through the contact is at or near its zero value. Current coils e<1>, c<2> also are provided on the relay, and are connected alternately in cireuit as the relay operates. A cut-off relay B is connected in the system and has operating coils h, i, j. The coils j are connected with an adjustable resistance n across the battery 0, the coils i are connected in series with the coils e<1>, e<2> of the rectifying relay, and the coils h and polarized tongue g carry the rectified current which passes through the load O. The coils i, j act differentially and, whenever the voltage on half the transformer winding exceeds the battery voltage, the tongue g is moved to the left to close the charging circuit. The whole of the secondary may be used for supplying the rectified current, and a second polarized tongue is then used on the rectifying relay. Where large currents and high voltages are employed, a number of polarized tongues may be used, and they mav be arranged in various combinations in series and parallel. In high-tension installations, the transformer windings are divided into sections which are connected in series to the circuit by numbers of the polarized tongues; and low-tension windings are placed on the transformers for connexion to the voltage windings on the relays. The construction of the relays is shown in Fig. 8. Three cores 1, 5, 6 carry separately the relay windings causing the tongues c, t to oscillate between the contacts b<1>, b<2>, t<1>, t<2> which are adjustably mounted on metal screws 8. 7, 9, 10 threaded in insulated metal plates. The cores are provided with polar extensions 19, 20, 21, 22. The arrangement of relays may be used for the rectification of three-phase currents. In this case, a transformer as shown in Fig. 16 may be used to ensure that power is obtained simultaneously from the three primary phases. The supply leads are connected to the primary windings P<4>, P<5>, P<6>; the secondary windings are interconnected and the terminals are connected to the windings of the separate transformers of the rectifying-apparatus.