Patent GB-395748-A (GB)
Title: Improvements in apparatus for commutating or periodically interrupting electric currents
IPC: H02M1/30
Filed: 1932-01-20
Abstract: 395,748. Rectifying alternating current. HARTMANN, J. F. G. P., 10, Kastelsvej, Copenhagen. Jan. 20, 1932, No. 1793. Convention date, March 5, 1931. [Class 38 (ii).] In a jet-wave mercury interrupter which may be used for rectifying electric currents the movable element consists of a series of equidistant substantially one - dimensional or two-dimensional conductors, (a jet conductor series), formed by a conductive liquid jet, these conductors moving with equal velocity in the direction of motion of the jet conductor and forming throughout their extent a considerable angle with the direction of movement of the said series. Two forms of the jet conductor series are shown in Figs. 1 and 2, in Fig. 1 the succeeding steps J1, J2, J3 forming portions of a mercury jet moving in the direction of the arrow V with equal velocity and in Fig. 2 these steps consisting of disc-like enlargements of the jet which are connected at their centres. Various applications of these jet-conductor series are described which may be employed as rectifiers, interrupters or converters from direct to alternating current, the electrodes and connections of which may be arranged in known manner, as, for. example, as shown in Specification 102,977, [Class 38 (ii), Electric currents, Converting &c.]. In Fig. 3 a series of the form shown in Fig. 1 connects fixed conductors E1, E2 successively to a plate E, the main dimensions of the conductors E1, E2 being perpendicular to the direction of motion of the jet conductor series. The plates E1, E2 are connected to the ends of a secondary winding V1, V2 of the supply transformer, the centre tapping of which is taken to the line L2 which with the line L1 connected to plate E are taken to the D.C. output terminals. The length of the fixed conductors E1, E2 is made equal to #/2, # being the distance between successive steps of the jet conductor series. Fixed knives W1, W2 are provided to assist in interrupting the circuit by cutting the jet at the end of each current impulse. A modified form of this type of rectifier employing a jet conductor series of the type shown in Fig. 2 is illustrated in Fig. 4 (not shown). Other modifications of Fig. 3 for full-wave and threephase rectifiers are also described. Numerous arrangements for producing the different forms of jet conductor series are described, electrical and mechanical methods being employed. In Fig. 7 a portion of the jet carrying direct current from a battery B passes through a rotating field formed by a magnet, system F, the consequent whirling of the jet in a conical path enabling portions a3, b3, a2, b2 and a1, b1 to be employed as members J1, J2, J3 of a jet conductor series. Alternatively a portion of a plane jet in a constant magnetic field may be supplied with alternating current to produce a vibration of the jet in a single plane. The jet conductor series in this arrangement is made to approach more nearly the theoretically perfect form shown in Fig. 1 with successive steps of the jet conductor -series substantially parallel to each other, by the current carried by the jet in the constant magnetic field being a double-period alternating current, i.e. having one half the'supply frequency. This current is produced by a jet-wave frequency changer of known construction which is arranged to produce a substantially square-peaked wave form. The jet conductor series may also be produced by electrically-produced vibrations of the jet nozzle or a purely mechanical method may be employed in which the jet is thrown out centrifugally from a rotating mercury container. The fixed contacts in this arrangement are arranged radially in the manner shown in Fig. 10 in which a three-phase arrangement is illustrated, contacts E1, E2, E3 being bridged successively by the jet portions to the contacts E, insulating partitions Y1, Y2, Y3 serving to separate the contacts of the different phases and to cut off the jet portions corresponding to these phases. Three transformer sections V1, V2, V3 are employed and fixed knives W1, W2, W3 are provided for ensuring interruption. The mechanically produced jets need not be confined to a single plane as the nozzle may be given a radial or tangential rotation relatively to the revolving container. In arrangements for producing a jet conductor series of the form shown in Fig. 2, an electromagnetic pump may be placed either directly in the mercury supplytube feeding the nozzle or in a branch tube communicating therewith, Figs. 33, 34, 35 (not shown). In the form shown in Fig. 37 a disc D in the mercury container is vibrated by an electromagnetic system of the form used in loudspeakers or alternatively the entire jet-producing system may be spring-mounted and vibrated electromagnetically. In all of these forms the vibration imparted to the mercury in the jet causes the formation of successive lateral bulgings P1 . . P4, Fig. 32, of the mercury jet until a jet conductor series approximating to the form shown in Fig. 2 is produced. In a further method of producing a series of this formation a pair of knife-shaped electrodes e1, e2, Fig. 36, vibrated synchronously with the supply current cut a slight distance into the sides of the jet J so as to pare off periodically very small shavings of mercury, the vibration of these knives produced by the interaction of current therein within the fixed magnet F causing formations approximating to the discshaped formations of the jet, shown in Fig. 2, which constitute the jet conductor series.