US2144421A - Rectifier of heavy electric currents - Google Patents

Description

Jan'. 17, i939. P. wANGl-:MANN

RECTIFIER OF HEAVY ELECTRIC CURRENTS Filed May l, 1936 3 Sheets-Sheet 1 Jan. 17, 1939. f P. WANGEMANN 2,144,421

RECTIFIER oF HEAVY ELECTRIC cURRENTs Filed May l, 1956 3 Sheets-Sheet 2 @-MWM Jan. 17, 1939. l WANGEMANN 2,144,421k

RECTIF'IER OF HEAVY ELECTRIC GURRENTS Filed May l, 1936 3 Sheets-Sheet 3 Patented Jan. 17, 1939 UNITED STATES PATENT OFFICE Application May 1, 1936, Serial No. 77,446 In Germany November 14, 1935 16 Claims.

In order to rectify heavy electric currents running sometimes even up to several thousands of amperes, the interruption must be made 'fty times per second according to the usual frequency of the alternating or multiphase currents. This is possible, only if the switching-olf is made without the slightest spark, because the light arc cannot be extinguished as quickly as the frequency of the current demands it. According to my invention, to rectify such enormous currents with the usual frequency an electrolytic jet is used, which bridges the space between two electrodes, at least one element being movable preferably rotatably. For rectifying purposes the switching is made preferably without voltage jump. In using an electrolytic jet, there must be no metallic contact between the electrodes at the point of interruption, that is to say, inside the electrolyte, to avoid any light arc or spark.

In case the process or apparatus is to be used also for regulating or starting purposes, a voltage jump cannot be avoided. In this case the cathode should always be covered by the electrolyte, so that the cathode spot shall not be formed on metal.

The formation of an arc is due to metallic vapours at the point of interruption. The arc is avoided when, at the point of interruption, no metals are present which owing to the cathodes spot might evaporate, and when, during the brief process of switching ofi, less resistance is offered to the migration of the ions through the conductor of the second class than to the migration of the electrons in the arc between the electrodes.

First class conductors are those with a positive temperature coemcient of resistance, for instance metals including mercury. Second classconductors are those with a negative temperature coeilcient, for instance electrolytes.

Mercury interrupters are known. Mercury, however, as a metal, is a conductor of the rst class. Therefore, when the slightest current is interrupted with "the aid of mercury, sparking cannot be avoided, because metallic vapour will always' be formed at the points of interruption, quite apart from the fact that in the case of metals, any distinction between anode and cathode would be superuous so far as the principle of the present invention is concerned. It is believed to be quite impossible to switch several thousands amperes fty times per second by the aid of mercury.

En the case of the sparkless system of interruption according to my invention direct current as` lvell as alternating current, coincident phase -A series of stationary electrodes 2-27 are and displaced phase can be switched off and owing to the sparkless interruption even repeatedly in the very briefest of intervals, for example, with the frequency of 50 periods per' second, so that this sparkless interruption can be used with 5 special advantage for heavy current rectiilers, motor and generator commutators and spasmodic regulators, for example, for the starting of motors.

In the following remarks, jet conductors of the second class are understood, even though only l0 electrolytes, electrolytic jets, or even only briefly jets or liquid jets are mentioned.

The forms of construction, by way of example of the invention, are shown diagrammatically in the accompanying drawings, in which- 15 Figure 1 is a horizontal sectional View through a circuit breaker for multi-switching Figure 1a is a partial illustration showing a. modication of the embodiment shown in Figure 1. 20

Fig. 2 is a similar view through a form of the invention designed for rectifying purposes and showing the electrical connections therefor.

Fig. 3is a vertical sectional view of the rectifier shown in Fig. 2. 25

Fig. 4 is a vertical sectional view of a modied form of rectier.

Fig. 5 is a horizontal sectional view of the rectifier shown in Fig. 4, partly broken away.

Figs. 6 to 14 are detail views of parts of the 30 rectifler, shown in Fig. 4 according to several modications.

Fig. l5 is a vertical sectional view of a modified form of a three-phase rectier with one electrolyte tank for each phase. 35

Figs. 16 and 17 are voltage diagrams.

Referring to the drawings in detail and in particular to Fig. 1, the numeral indicates a conw tainer for the electrolyte 4, the container in the form of a cylinder with a vertical a is. 4:0 An insulating cylinder 5 is rotatably mounted concentrically with the axis of the container 3.

cured in an annular group to the wall oi t.'- container 3 above the level of the electrolyte with W the operative faces thereof in close proximity the surface or" the insulating s tionary electrodes i-lV are arranged within insulating cylinder 5 and are in the form of nozezles, through which the electrolyte is forced in the form oi a jet towards the respective outside electrodes 2 2". The insulating cylinder or drinn 5 is formed with a slot Si which, as said cylinder is rotated, successively uncovers one of the several nozzle-like electrodes i and permits the l of electrolyte issuing therefrom to impinge upon the adjacent phase electrode 2-2V and thereby complete the electrical connection between these electrodes and for a brief period, the electrolyte returning by gravity to the bottom of the container 3 and the jet being interrupted by the trailing edge of the slot 9 as the rotary movement of the insulating cylinder continues.

A circuit breaker of this type ls capable of use as a rectifier and in this case the outside electrodes 2-2V insulated from each other are con-r. nected with the individual phases of the multiphase alternating current. 'I'he width of the slot 9 determines the duration of the circuit closing period between the pairs of electrodes I and 2 and preferably the width of said slot is such that for a brief moment, two jets from the nozzlelike electrodes IIV contact simultaneously with i the related electrodes 2-2V so that the switchingover from one phase to another is effected without jump of voltage or interruption of current as indicated in the diagram in Fig. 16 hereinafter more fully described.

The slot 9 can be closed by a metal plate 9' as shown on `the partial diagram according to Figure 1a. In this case also each of the outside electrodes 2-2V forms a nozzle and ejects an electrolyte jet. When the'jets of the electrodes I and the jets of the electrodes 2, beat at the same time the metal plate 9' inserted in the slot 9, the circuit is closed. Itis possible to avoid the metal plate. In this case the two jets of the electrodes I and 2" collide, but the metal plate has the advantage that the jets ow more smoothly.

It will be noticed that in the arrangement illustrated the phase electrodes 2-2V are widely spaced apart and being adequately insulated, the arrangement is particularly advantageous for the rectification of alternating currents of very high voltage.

Referring to the arrangement shown in Fig. 2 a system of connections for multi-phase rectication is illustrated in combination with a modified form of circuit breaker. In place of the slotted insulating cylinder shown in Fig. 1, a rotating electrolytic jet is used as the contact maker. As in the case of the arrangement shown in Fig. l the nozzle-like electrode In rotates in synchronism with the alternating current supply. In order to reduce the number of revolutions required for rectifying purposes, a double number of poles can be employed.

As shown in Fig. 2 on the three-phase alternating current side, the ends I2 of the windings of a transformer are` connected to the related electrodes 2a and the neutral point I3 of the transformer or another artificial neutral point of the system forms one direct current pole while the rotating nozzle-like electrode I* and the jet of electrolyte discharged therefrom forms the other direct current pole.

The nozzle-like electrode Ia for the electrolyte jet is preferably the cathode and electrode 2 the anode. In this case the electrolytic jet discharged from the nozzle-like electrode I covers the cathode so that the formation of the cathode spot is avoided. Theliquid jet will therefore move in a. direction opposite to that of the elec-' rotation, the electrolyte is -forced upwardly through the hollow electrode I and discharged from the upper nozzle-like portions thereof.

In order to avoid creeping currents due to the electrolyte dripping from the electrodes 2* the vessel is preferably provided with an air ring 3'. It will be noted that the construction shown in Fig. 1 differs from that disclosed in Figs. 2 and 3 only insofar that in the case of Fig. l a slotted insulating drum rotates in front of as many stationary nozzle-like electrodes I-IV as there are phase electrodes, whereas in the form of construction in Figs. 2 and 3 only one or one pair of nozzles is provided without the insulating drum.

One of the most important advantages of the present rectifier system consists in that no slip rings are required. 'I'he phase electrodes are stationary and are connected with fixed cables. According to the arrangement `shown in Fig. l the nozzle-like electrodes are also stationary and are similarly connected to fixed cables, whereas in` the case of rectiiiers with a rotating nozzle-like electrode I, the currentis conducted from the bottom of the container 3 by means of cable connection I5 and the electrodes 2 are positioned above and out of contact with the body of the electrolyte.

According to the arrangement shown in Figs. 4 and 5, the electrodes 2b are arranged in a horizontal plane and the nozzle-like electrode I is correspondingly arranged. The rotor I6 is rotatable around a vertical axis and is constituted by a hollow cone the lower open end which is immersed in the electrolyte 4b in the bottom of the container 3b and the upper end thereof is in communication with head I8. The nozzle-like electrode Ib is in communication with the head I6' and during rotation of the cone I 6, the electrolyte is raised by suction entering the head I6', thus iiows outwardly and downwardly through the open nozzle without appreciable pressure. v

The fixed electrodes 2b are preferably formed of ring sections having wedge-shaped cross sections, the members of each electrode being heid in spaced relation by suitable spacing members as shown in Fig. 6. 'I'he individual electrodes 2b are of arcuate form and separated by radial slots I8. These electrodes 2b are fastened to the cover of the vessel 3b by means of insulating brackets I8.

The container cover also carries the motor MP the rotor I6 with the head I6' and nozzle Ib by means of the bearing arm 20 whereby the mutual` adjustment ofthe electrodes Ib and 2h can be effected when these parts are removed from the vessel as a unit with the cover.

The advantage of this design of the electrodes Ib and 2b lies in the fact that the electrolyte jet passes tangentially through the wedge-shaped members 2l in the nozzle-like electrode Ib and flows tangentially downwards around the wedgeshaped ring segments of the electrode 2b. In this way it is possible to greatly increase the area of contact surface between the electrode and electrolyte, to regulate the thickness of the electrolytlc jet by raising the rotor I6 vertically and entirely avoidingthe electrolyte becoming atomized by striking against the electrodes 2b, owing to the fact that the jet, in this case, is not subjected to appreciable pressure which might tend to produce an atomizing effect.

Fig. 7 shows in section a modified form of the nozzle I and the stationary electrode 2. The rotating electrode Ic has wedge-shaped members or liners 2| and 2I tapering ci! towards the top.

The liners 2|' engage between the stationary rings of the electrode 2. The liners 2l lie opposite those stationary rings of the electrode 2c, so that the electrolyte can pass .over without eddies. In this arrangement it is immaterial whether the tongues of the liners 2l' which engage between the rings of the stationary electrodes 2c taper off downwards or are parallel. An insulating apron 26, one for each phase, deilects the liquid preferably to the wall of the con-v tainer 3. x

If the circuit breaker is used for rectifying purposes a jump of voltage should be avoided if the jet of the electrode Id pass over from one electrode 2d to the next one as shown in Fig. 8.

Fig. 16 shows a diagram of the voltage of the different phases I, II, III, IV, V, VI. The part I from a to (a) is cut out by the electrolytic jet touching one electrode. The electrolytic jet should pass over to the next electrode 2d in Fig. 8

in the moment where the voltages of phase I andy phase II are the same. In this case the passing over of the electrolytic contact from phase I to phase II is done without a jump of voltage. Ifi.

the electrolytic jet leaves the left electrode 2d in Fig. 8 before the electrolytic jet reaches the right electrode 2d the current is completely interrupted of the phase electrodes I, II, III should not beA longer'than 2 or 3 angle degrees. For this reason the electrolytic jet from the nozzle electrode Id is wider than the slot I8 in Fig. 8. To avoid a longer short circuit between the subsequent phase electrodes it is important that the electrolytic jet is ejected straight out avoiding a curved flag of the electrolytic jet at the outlet of the rotating nozzle. The contour of the flag is shown in Fig, 9. The most effective means, however, is to use a jet of compressed air which deilects the freely emerging liquid jet with strong air pressure as soon as it has left the tongues 2| of the nozzle. In Fig. 11 the mouth of the tube for the i compressed air is denoted by 3| and is at right angles to the direction in which the emerging jet of the electrolyte moves, so that the jet 30 of liquid is deflected in the direction of this jet of compressed air without the stationary electrodes being touched further by it. In Fig. 12 the compressed air nozzle rotates with the electrolyte nozzle Id. For this purpose a Pitot tube 36 is mounted on the rotating nozzle ld and opens into the air pressure nozzle 33, which passes behind the emerging jet 30 of liquid. In front in the direction of motion the Pitot tube has the mouthpiece 42. 'Ihe direction of the jet may also be assisted by arranging a suction device 34 with an injector nozzle 35 in front of the jet. In Fig. 13

the jet nozzle Id with the rotor 38 is shown in side elevation. The rotor may consist of a forked tube 31, 3B which may be closed by a foot valve 40. 'I'he forked piece 31 may be advantageously sloped, so that the surface of `the liquid remains at the level 39. .At the commencement of the rotation this quantity of the electrolyte will be centrifugally projected outwards and will instantly createsuction. 'Ihe individual phase apron 26 of the Fig. 7 can be fixed as 26 on the rotor so that it is always underneath the nozzle Id and receives the emerging jet, especially if in the rotating apron 26 a suction effect is produced. Instead of the ball valve 40 in the rotating tube 38 the tube 40 may be stationary and surround a rotating conveyor screw, which is driven by the rotating part 31 inside the collar of the stationary tube 42 of Fig 14. Instead of only one rotating nozzle i a rotating nozzle Ie in tanks 3e insulated from each other is provided in Fig. '15 for each phase. This construction is adapted especially for the rectifying of high voltage currents. It is obvious, that in this construction the emerging flag of this jet may be rendered innocuous by the space between the single electrodes 2, by using different liquid tanks for the several stationary, electrodes of different phases are shown in Fig. 15.

If the rectier is to be used at the same time as a starter, the electrodes 2b' may be tapered radially and inwardly as shown in Fig. 5. In this case, by meansvof a suitable deection, not shown, of the electrolytic jet, the current is interrupted for a considerable period during the moment it passes over from one electrode to the other. The circuit closing periods are at rst brief and increase gradually as the jet is deflected outwardly until the closureperiod remains uninterrupted as when the jet assumes the position shown in Fig. 4. Vertical electrodes 2a have their tapered part above or below the normal position of the rotor which is then displaced in height, as shown in Fig. 3.

For operation, two points are important, rst, the deaeration of the vessel 3b in order to carry off the products of electrolysis. For this purpose the rotor i6 is provided with a Ventilating device 22 preferably mounted on the circumference thereof and which draws air out of the openings 23 through electrode slots 2b and forces it upwardly through the air vents 24. The second important point is the heat regulation of the electrolyte 4b. Conductors of the second class have a negative temperature coeicient which is many times that of the temperature coeilcient of metal, consequently the internal resistance will diminish considerably when the temperature is increased and at it will be down to half, relatively to the resistance of the temperature of the air, the degree of eiciency will accordingly increase very considerably if the temperature is kept at a temperature of a few degrees below 100.

The regulation of the temperature is most readily eifected by means of a heat protective and insulating jacket 25 which at the top or at the bottom is formed with a bent edge 25' so that the current of air flowing between the vessel ilb and the jacket 25 may be regulated by raising or lowering said jacket. Under the electrodes 2b, a cone-shaped insulating ring 26 is mounted which deflects the electrolyte jet towards the Wall of the container 3b and allows it to drip downwardly. At the same time the ring serves to change the direc-tion of the fresh air supplied by the openirgs 23.

The regulation of the average current at a. constant voltage is afforded by the tapering of the anodes 2'l and 2b toward the center but even without any interruption of the current, the voltage may also be regulated, for example, for the purpose of starting motors. Fig. 16 illustrates the normal course of the voltage with six impulses of very low amplitude in the case oi.' a

- Awheels.

three-phase alternating current. If, however, as shown in Fig. 17, the nozzle 21 is turned in phase relatively to the phase coincidence synchronism, a diminution of the voltage can be produced. If two nozzles 21 and 28 in two vessels separated one fromthe other is used, the voltage curve 29 is obtained. If, on the other hand, the nozzle 28 is turned relatively to the nozzle 21 through an angle, for example, of 60, the voltage curve 30 Iwill be attained. If now we call the angle enclosed by the two nozzles 180-a, the best possible curve will be obtained when the nozzle 21 is turned back through a:2 and the nozzle 28 through 3a:2. By mechanical means the ratio 1:3 may be attained by displacing the casing of the synchronous motors by means of worm 'I'his displacement can also be attained by electrical means by super-exciting the synchronous motors. In this case the same shape of curve as that at full voltage can be obtained. One single jet contact in only one vessel will suffice, but in this case the voltage curve will be distorted but nevertheless will be continuous. During the brief moment of starting, however, the distortion ofthe voltage curve is not of consequence. A

What I claim is:

'1. In a device for sparklessly rectifying heavy electric currents, a polyphase current supply system, stationary phase electrodes in fixed connection with the phase lines, at least one nozzle electrode constituting a direct current pole, said nozzle electrode being adapted to discharge an electrolytic jet into c ontact with the phase electrodes.

2. In a device for sparklessly rectifying heavy electric currents, a polyphase current supply system, at least one synchronously rotatable electrolytic jet, a nozzle for the said jet constituting one cathode, and stationary phase electrodes connected with said system, the said stationary phase electrodes being touched by the said electrolytic jet and constituting the anodes.

3. In a device for sparklessly rectifying heavy electric currents, at least one electrolytic jet, electrodes, at least one of said electrodes forming a. synchronously rotatable nozzle for the said electrolytic jet adapted to constitute a oontactbetween a series of other of said electrodes, a container for the` electrolyte for supplying the electrolytic jet, the said nozzle being sloped forwardly in the direction of rotation.

4. In a device for sparklessly rectifying heavy electric currents, at least one electrolytic jet, electrodes, at least one of the said electrodes forming a synchronously rotating nozzle for the said electrolytic jet adapted to constitute a connection between the nozzle electrode and a series of other said electrodes, a container for an electrolyte for supplying the electrolytic jet, and

means rotating synchronously with the said nozzle electrode for collecting and deilecting the electrolyte jet after its passage over the electrodes of said series.

5. In a device for sparklessly rectifying heavy electric currents, at least one electrolytic iet, one elec-trode forming a nozzle for the said electrolytic :let adapted to constitute a connection between the nozzle electrode and the other electrodes. and means for regulating the temperature of the electrolyte.

6. In a device for sparklessly rectifying heavy electric currents, atleast one electrolytic jet, electrodes, at least one of said electrodes forming a synchronously rotatable nozzle'for the said electrolytic jet adapted to constitute a connection between a series of otherof said electrodes, the said electrodes being so spaced that the said electrolytic jet is adapted to touch simultaneously two adjacent electrodes.

7. In a device for sparklessly rectifying heavy alternating electric currents, at least one electrolytic jet, electrodes, at least one of the said electrodes forming a synchronously rotating nozzle for the said electrolytic jet adapted to constitute a connection between the nozzle electrode and a series of other of said electrodes, and means for regulating the direct current voltage by displacing the said synchronously rotating nozzle out of phase coincidence relation to the alternating current system.

8. In a device for sparklessly rectifying heavy electric currents, electrodes, at least one .electrolytic jet adapted to constitute a connection between two opposite electrodes and means adapted to guide the electrolytic jet tangentially along the said electrodes.

A9. In a device for sparklessly rectifyingy heavy electric currents, electrodes, at least one electrolytic jet, adapted to constitute a connection between the said electrodes, said electrodes having partition walls adapted to guide the electrolytic jet parallel to the said partition walls from thenozzle electrode to the touched electrode.

` 10. In a device for sparklessly rectifying heavy electric currents, electrodes, at least one electrolytic jet, adapted to constitute a connection' between the said electrodes, the said electrodes having interspersed partition walls adapted to guide tangentially the electrolytic jet between the electrodes.

11. In a device for sparklessly rectifying heavy electric currents, electrodes, at least one electrolytic jet, adapted to constitute a connection between the said electrodes, the said electrodes having interspersed partition walls adapted to guide the electrolyte while crossing the space between the said partition walls. y

12. In a device for sparklessly rectifying heavy electric currents, electrodes, at least one electrolytic jet,4 adapted to constitute a connection between the said electrodes, having partition walls composed of conducting segments separated by spacing pieces.

13. In a device for sparklessly rectifying heavy electric currents, at least one electrolytic jet, electrodes, one of said electrodes forming a nozzle for the said electrolytic jet adapted to constitute a connection between the said nozzle electrode and another touched electrode, and means adapted to adjust the nozzle electrode axially relative to the touched electrode.

14. In a device for sparklessly rectifying heavy alternating currents, electrodes spaced from each other and connected to the respective alternating current lines, a nozzle electrode for an electrolytic jet, said jet being adapted to touch one of said spaced electrodes after another in syn- .chronism with the alternating current supply and to touch two of -said spaced electrodes simultaneously while switching over from one touched electrode to the next one, the nozzle electrode constituting the cathode and the touched electrodes the anodes.

15. In adevice for sparklessly rectifying heavy alternating currents, a plurality of nozzles for electrolytic jets, electrodes connected Ato the respective alternating current lines, and means for` causing said electrolytic jets to touch their respective line electrodes periodically in synchronism with the alternating current supply, each line electrode and its co-acting nozzle and jet being contained in a separate container.

16. In a device for sparklessly rectfying heavy electric currents, a container, an electrolyte therein, means for producing at least one electrolytic jet, electrodes, one of said electrodes forming a rotating nozzle for said electrolytic jet adapted to constitute a connection between the nozzle electrode and another touched electrode, means adapted to adjust the nozzle electrode axially relative to the touched electrode, said nozale electrode comprising a central tube immersed in said electrolyte, and means to liit continuously the electrolyte from the bottom of said container to said nozzle.

PAUL WANGEMANN.

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