Patent GB-463355-A (GB)
Title: Improvements in and relating to rotary commutator switching-apparatus for converting electric currents
IPC: H02M1/22
Filed: 1936-04-27
Abstract: 463,355. High tension switches. SIEMENS-SCHUCKERTWERKE AKT.-GES. April 27, 1936, Nos. 11879, 11880, 11881, and 11882. Convention dates, April 29, 1935, May 28, 1935, May 28, 1935, and June 12, 1935. [Class 38 (v)] A rotary commutator switching - apparatus for converting hightension currents is provided with arc-quenching means employing a flowing medium, with guiding means for the quenching medium so arranged as to direct the medium on to the arc in the immediate vicinity of the relatively movable electrodes and to constrain the arc within the medium so that it cannot be drawn out into a loop. In one arrangement, Fig. 1, a disc 1 carrying arcshaped electrodes 5, 6 connected to slip rings 7, 8 is rotated in synchronism with the alternating current, the three phases of which are connected to stationary electrodes 9, 20, 21 spaced 120‹ apart. Each of the stationary electrodes is provided with an arc-quenching device comprising an insulating tube 11 having holes 12, 13 and a slot through which the movable electrodes 5, 6 and the disc 1 pass, the stationary electrode 9 being provided with a similar hole and slot. The arc formed between the electrodes 5, 9 is drawn into the tube 11, where it is subjected to a powerful blast of compressed air admitted through a tube 18. In a modification, Fig. 4, the electrodes 32, 33 are placed in a vessel 30 containing compressed air, the stationary electrode 33 forming the edge of a nozzle 34 which may be formed of metal. The nozzle is carried by an insulating bushing 36 and communicates with the atmosphere through a throttle opening 38. The rotating electrode 32 also carries a nozzle 39 which communicates with the atmosphere through the hollow spindle 31. In operation, compressed air flows from the casing through the nozzles. The latter are provided with conductive insets 41, 42 to obviate lengthening of the arc. In a modification of the last construction, the nozzles are provided with arcuate inlet openings for the pressure medium, which surround the outlet openings. In other constructions, several quenching arrangements are provided along the arc. One such construction is shown in Fig. 8, in which the rotating electrode 132 carries three outlet nozzles 139, 153, 154, and the fixed electrode 133 also has three nozzles 134, 151 and 152. The quenching medium is under pressure and passes through the nozzles to the outlet pipes 135, 140. The nozzles 134, 139 are made of metal and connected to the electrodes ; the other nozzles are of insulating material, but may be provided with metal insets 155 at the points in contact with the arc. In the construction shown in Figs. 9 and 10 the stationary electrodes are in the form of elongated conductive nozzles 204 connected to contact slides 207 of arcuate form, with which the rotating electrodes 205, which are also in the form of elongated nozzles, make contact. Conductive cross-bars 209, 210 are mounted inside the nozzles to prevent lengthening of the arc. The quenching medium, which may be compressed gas, flows from the casing through the nozzles. In another construction, Fig. 14 (not shown), the quenching medium flows towards the electrodes through a supply nozzle concentrically surrounding an outlet nozzle, so that the medium flows in countercurrent through the inlet and outlet nozzles. Liquid as well as gaseous quenching media may be used. The electrodes need not be in actual contact during the commutation periods, but may be arranged a short distance apart so that the current passes by sparking between them. The flow of quenching inedium may be controlled so that it exists only for the duration of the arc.