US2140736A - Arrangement of two or more anodes for rectifiers provided with control electrodes - Google Patents

Description

M DEMONTVIGNIER PROVIDED WITH CONTROL ELECTRODES Filed Dec. 5, 1932 a E 2 M a 0 5 w Q2. 6 5% 4 .1 fi v (IT/F M 7.

wt 1 w 3 ARRANGEMENT ,OF TWO OR MORE ANODES FOR RECTIFIERS Dec. 20, 1938.

Patented Dec. 20, 1938 UNITED STATES PATENT QFFEE ARRANGEDIENT OF TWO OR MORE AN ODES FOR RECTIFKERS PROVIDED WITH CON- TROL ELECTRODES Application December 3, 1932, Serial No. 645,633 In France December 23, 1931 7 Claims.

The parallel operation of two or more anodes for arc rectifiers such as mercury vapour rectifiers in which the anodes may be in the same container or separate containers, ofiers certain difficulties on account of the negative resistance of the are. It is already known that this parallel operation may be effected in various ways: for exam le, an inductance may be provided for each anode which, by its inductive potential drop, will compensate the negative resistance of the arc; it is also possible to couple the dillerent anode circuits magnetically in such a way that any anode the ignition of which is retarded, receives an inductive electromotive force in consequence of the ignition of the preceding anodes,

which will cause it to ignite. As wil be readily appreciated, a coupling of this kind likewise enables the differences in the drop of potential in the arc to be compensated. In the case in which the anodes required to operate in parallel are provided with one or more control internal electrodes or external electrodes in their vicinity, the purpose of which is either to eliminate the residual ionization which causes back-firing or to control the moment of ignition, these arrangements may be employed; it has been proposed merely to connect the control electrodes in parallel and to the common voltage supply, either directly or through resistances. This method is accompanied by a serious drawback: actually, when a control electrode has effected the ignition of a single anode, its voltage drops immediately at the same time as that of the other electrodes; consequently, the ignition of the other electrodes is rendered more difficult and the magnetic coupling arran ement between the anodes must be strengthened in such a way as to give the necessary impulse to the other anodes.

The object of the present invention is to provide an arrangement which in the case of the parallel operation of two or more anodes provided with grids enables a magnetic coupling system to be employed between the anode circuits, which is reduced to the dimensions necessary for compensating the differences of potential drop in the arc, the control electrode circuits being coupled magnetically to one another and to the anode circuits in such a way that the control electrode for an anode the ignition of which is delayed, will receive a positive voltage impulse owing to the ignition of the other anodes, which will effect the ignition of the retarded anode.

The following description which is given by way of example with reference: to the accompanying drawing and is in no way limiting, will enable the principle of the invention and the methods of carrying it into practice to be better understood.

Fig. 1 shows the arrangement suitable for the parallel operation of two anodes provided with inductance coils and grids.

Fig. 2 shows the corresponding arrangement for three anodes.

Fig. 3 shows the arrangement which may be employed in the case of the parallel operation of two anodes supplied by two windings in phase with one another on the same transformer.

Fig. 4 shows an arrangement combining the magnetic coupling between two anodes and their control grids in the same magnetic circuit.

Finally, Fig. 5 shows the corresponding arrangement for three electrodes.

Referring to Fig. l the common busbar I, connected to a terminal of the secondary of the supply transformer, feeds the two anodes 2 and 3 through inductances i and 5. Between the anodes 2 and 3 the primary of a small singlephase transformer is connected; the secondary, which has a very much greater number of turns than the primary is provided with a centre tap i connected to one of the terminals of the common supply 8 for controlling the grids, the ot er terminal of the same, which is shown, free in the figure, being connected to a suitable point in the system. The two ends of the secondary for the grid transformer are connected respectively to the grids 9 and il the direction of coupling being that shown in the figure, assuming the primary and secondary of the grid transformer to be wound in the same direction. With this state of affairs let it be assumed for example that under the influence of the supply 8 the grid 5 controls the first ignition of the anode 2; under these conditions this anode will undergo a sudden drop of potential, equal to the difierence between the ignition voltage and the drop of potential in the arc (the ignition voltage being moreover determined by the selection of the moment of ignition caused the supply 8). As the voltage of the anode 3 does not undergo any change, a difference of voltage will appear suddenly between the terminals of the primary t. This difference of voltage will reappear, multiplied by the transmission ratio, between the terminal l and the grid iii, the latter being suddenly rendered positive. As the voltage of the anode 3 will then be greater than that of the anode 2 (owing to the inductive drop in the inductance Q) the anode 3 will be ignited. In other words, the retarding of the ignition of one anode produces a sudden positive potential impulse upon its grid. This impulse may be made as strong as desired by increasing the transformation ratio of the grid transformer, the latter being moreover very small owing to the low value of the grid currents. Under these conditions the anodes will ignite substantially at the same time (actually, experience has shown that the retardation is very difficult to determine), and the anode inductances are only required to compensate the differences of the potential drop in the ignited arc.

This system may conveniently be applied generally to the parallel operation of three anodes provided with inductances: for example three grid transformers may be employed arranged in a manner similar to that of Fig. 1, between each of three anode couplings associated in pairs, the three centre points of the three secondaries being connected to one another and to the common supply for the grids, and each of these latter being connected to two secondary terminals of two grid transformers. It will then be readily appreciated that any anode which ignites prematurely will apply to the grids of the two others a sudden voltage impulse which effect their ignition. Itis moreover possible to eliminate one of the three transformers without any inconvenience resulting. Further, as shown in Fig. 2, it is possible to combine in one magnetic circuit having three cores the elements for the grid transformer required for the parallel operation of three anodes provided with inductances. Referring to Fig. 2, the common busbar feeds the three anodes l2, l3 and I4 through inductances |5, I 6 and I1. On the other hand three coils I9, 20 and 2| connected in star are placed in a magnetic circuit l8 having three cores, the free ends of the coils being connected to the terminals of these three anodes. In the same circuit there are also three coils 22, 23 and 24 likewise coupled in star, the neutral point being connected to one of the terminals of the control supply 25 for the grids whilst the other terminal is connected to a suitable point in the system. The free ends of the coils 22, 23 and 24 are connected respectively to grids 26, 21 and 28. Let it now be assumed that under the influence of the supply 25, the anode l2 ignites first for example: a sudden drop it of its potential will result with respect to that of the anodes I3 and 4. It will readily be seen that this sudden drop of potential will take the form of the sudden appearance in the coils I9, 20 and 2| of the voltages 2a 2 Y 3 and respectively, these voltages being reckoned positively from the neutral point. These voltages will obviously reappear in the secondary, multiplied by the transformation ratio. Consequently the grids 21 and 28 corresponding to the anodes l3 and 4 will each receive a positive voltage impulse causing ignition. Similarly, if two anodes ignite in advance, the grid of the third will receive an impulse causing ignition. These arrangements may be extended without difficulty to any number of anodes provided with inductances either when employing n or n1 single-phase grid transformers or a single transformer with 12 cores.

Similarly, instead of employing independent inductances in the anode circuits, it is possible to employ magnetically coupled inductances or independent windings on the supply transformer, these windings giving voltages in the phase with one another and being provided with a magnetic coupling producing the inductance for the coupled anodes within the transformer.

Referring to Fig. 3, a single-phase grid transformer is shown for example which is employed to produce the simultaneous ignition of two anodes, all these members having the same references as in Fig. 1, but the anodes are supplied by two independent windings 29 and 30 coupled together in the magnetic circuit of the supply transformer.

Finally, in order to ensure the parallel operation and simultaneous ignition of two or more anodes for restifiers supplied with control electrodes, it is possible to combine in the same magnetic circuit the windings traversed by the anode currents and the windings employed for operating the control electrodes. This is shown in Figures 4 and 5.

Referring to Fig. 4, in a single-phase magnetic circuit 3|, two windings 32 and 33 inserted in the circuits of the two anodes 34 and 35 so that their ampere turns are in opposition are shown. On the other hand the control voltage supply 36 feeds the grids 31 and 38 through fine wire windings 39 and 40 which are likewise in opposition in the magnetic circuit. The operation is as follows. If under the influence of the supply 36, the anode 34 ignites first, a sudden decrease of potential will be produced between the terminal 4| of the supply transformer secondary and the anode 34. On the other hand, owing to the induction there will be a sudden increase of potential between the anode 35 and terminal 4| on the one hand, and on the other hand at the grid 38 in a similar manner to that described above. These two increases of voltage will cause the immediate ignition of the anode 35. It will be readily understood that when the two anodes are ignited, the two windings 32 and 33 compensate the differences of potential drop in the arc, the out-ofbalance current produced by a given difference of the two potential drops being as much less as the increase of the inductance in the windings.

The interesting feature of this arrangement is found in the fact that the heavy wire winding only has to compensate the difierences of potential drop in the arc and may be reduced to a minimum, the differences of ignition voltage being compensated by the fine wire winding.

Referring to Fig. 5, the application of an arrangement similar to the parallel operation of three anodes is shown; the terminal 42 for the secondary of the supply transformer is connected to three anodes 49, 50 and 5| through three heavy wire windings 43, 44 and 45 placed in the magnetic circuit with three cores 56. In this same circuit three fine wire windings are located which are coupled in star, the common point being connected to the control voltage supply 55 and the free-ends being connected to grids 52, 53 and 54. The operation is analogous to that of the preceding arrangement, the fine wire windings producing the simultaneous ignition of the three anodes and the heavy wire windings compensating the differences of potential drop in the arc. This compensation is only perfect when the reluctances of the magnetic circuits corresponding to the three cores are equal, or when the numbers of turns are selected in inverse relation to the reluctances.

In order to obtain parallel operation with three anodes it is also possible to associate three systems identical to that shown in Fig. 4, in such a way as to ensure the parallel operation of three pairs of anodes combined in pairs.

These systems may also be extended to any number of anodes.

It has been assumed in what has been said above that the control electrodes took the form of grids. The systems described may be applied without modification to a method of control with external electrodes. Similarly it is possible to insert in the control electrode circuits resistances or impedances of any kind which are located above or below the arrangements described.

I claim:

1. In a rectifying system, anodes connected in parallel with the same phase of a supply transformer, an inductance in series with each of said anodes, a control electrode for each of said anodes, a winding in series with each control electrode, and a means magnetically coupling each of said control electrode windings and with all of said anode inductances.

2. In an electric translating circuit, a plurality of grid controlled vapor electric valves connected in parallel, a grid circuit for each of said valves, means for exciting said grid circuits normally to render said valves conductive simultaneously, a reactance device comprising a multi-legged core member and an inductive winding mounted on each leg of said core, one of said windings being connected in the anode-cathode circuit of each of said valves, and an auxiliary inductive winding coupled to each of said first mentioned windings and connected in circuit with the grid of its corresponding valve, said, auxiliary windings being effective upon the initiation of current in any of said valves to impress positive impulses on the grids of the non-conductive valves.

3. In an electric translating system, the combination with a source of electric current, electric valve means comprising a plurality of anodes and a plurality of control electrodes severally associated with said anodes, and means comprising a first plurality of windings severally connecting said anodes with said source of current, of means comprising a second plurality of windings severally connected with said control electrodes and operable to excite the latter in such sense as to continually render the said anodes simultaneously conductive for the flow of current from said source by way of the said first plurality of windings, and means inductively coupling each winding of the said first plurality thereof with all of the said second plurality of windings to thereby additionally excite said control electrodes upon the occurrence of the initiation of said flow of current through any one of said anodes.

4. In an electric translating system, the combination with a source of electric current, electric valve means comprising a plurality of anodes and a plurality of control electrodes severally associated with said anodes, and means comprising a first plurality of windings severally connecting said anodes with said source of current,

of means comprising a second plurality of windings severally connected with said control electrodes and operable to excite the latter in such sense as to continually render said anodes simultaneously conductive for the flow of current from said source by way of the said first plurality of windings, and means comprising a member of paramagnetic material inductively coupling each winding of the said first plurality of winds with all of the said second plurality of windings to thereby additionally excite said control electrodes upon the occurrence of the initiation of said flow of current through any one of said anodes.

5. In an electric translating system, the combination with a source of electric current, electric valve means comprising a plurality of anodes and a plurality of control electrodes severally associated with said anodes, and a plurality of inductors severally connecting said anodes with said source of current, of means for exciting said control electrodes in such sense as to continually render said anodes simultaneously conductive for the flow of current from said source by way of said inductors, the last said means comprising a transformer having a primary winding connected across said anodes and a secondary winding having a plurality of portions severally connected with said control electrodes and operable to additionally excite said control electrodes upon the intiation of said flow of current through any one of said anodes.

6. In an electric translating system, the combination with a source of electric current, electric valve means comprising a plurality of anodes and a plurality of control electrodes severally associated with said anodes, and a plurality of inductors severally connecting said anodes with said source of current, of means for exciting said control electrodes in such sense as to continually render said anodes simultaneously conductive for the flow of current from said source by way of said inductors, the last said means comprising a transformer having a plurality of primary windings severally connected with said anodes and a plurality of secondary windings severally connected with said control electrodes and severally inductively linked with all of said primary windings to thereby additionally excite the said control electrodes upon the initiation of said flow of current through any one of said anodes.

7. In an electric translating system, the combination with electric valve means comprising a plurality of anodes and a plurality of control electrodes severally associated with said anodes, of means comprising a plurality of winding portions severally connected with said control electrodes for exciting the latter in such sense as to render the said anodes simultaneously conductive for the flow of current, and means for additionally exciting said control electrodes upon the occurrence of the initiation of the flow of current through any one of said anodes comprising a winding having connection with at least two of said anodes, and a member of paramagnetic material inductively coupling the said winding with said plurality of winding portions.

MARCEL DEMONTVIGNIER.

Images