US2040748A - Vapor electric discharge device - Google Patents

Description

May 12 L.. LERQY 2949745 VAPOR ELECTRIC DISCHARGE DEVICE Filed May la,l 1934 5 sheets-shew 1 J] @WMM/f 40m @mmm-MM@ @M may m w36.; L LER@ www VAPOR ELECTRIC DISCHARGE DEVICE Filed May 18, 1954 n 5 Sheets-Shee 2 @by 32, M36.,- L. LEROY @@fmg v VAPGR ELECTRIC DISCHARGE DEVICE Filed May 18, 1954 5 Sheets-Sheet 5 L. ENERGY VAPOR ELECTRIC DISCHARGE DEVICE 5 Shee'bs-Sheet Filed May 18, 1934 l LEROY VAPOR ELECTRC DISCHARGE DEVICE Filed My la, 1934 5 sheets-sheet 5 Patented May 12, 1936 UNi'rsD srarss PATENT OFFICE VAPOR ELECTRIC DISCHARGE DEVICE Application May 18, 1934, Serial No. 726,405 In France May 23, 1933 17 Claims.

'Ihe present invention relates to vapor electric discharge devices having anode-control grids, and it has for its object to provide improved means for the regulation of the rectified voltage as a function of the output current, or of the current as a function either of the power output or of the current supplied by any other apparatus coupled in parallel.

The invention provides for the automatic regulation of a discharge device employed as rectifier, particularly in compounding to give constant voltage at varying output, over-compounding, under-compounding, operation at constant current with varying power, parallel working, and connection to a supply system fed by one or more other sources of continuous current. This regulation is effected automatically by the use of an auxiliary generator or exciter or the type having three eld windings, one being a shunt winding and the others acting in opposition to one another, the voltage of the auxiliary generator or V exciter being combined with the alternating bias voltage applied to the anode-control grids so as to render the rectifier independent of its own normal characteristic and of the variations of the external or output circuit and to endow it with the desired characteristic, which may be that of a reference machine of very small power.

In general, the alternating voltage applied to the control grids will have the same frequency as the anode voltage, but it may be of differentI frequency. rIihe regulation of the rectifier is rendered independent of possible variations of the grid blocking or biasing voltage. It is possible to obtain a very high accuracy of regulation by the use of a series motor included in the grid circuit and operating as a negative resistance.

The invention is hereafter described with reference to the accompanying drawings, in which:-

Fig. l is a diagram illustrating a known method of regulating the moment of ignition in a rectifier of the va'por electric discharge type.

Fig. 2 is a diagram illustrating the normal operation of a three field winding exciter, of which the essential parts are shown in Fig. 3.

Fig. 4 is a diagram corresponding to Fig. 2, but illustrating the operation of the three field winding exciter as applied in the present invention.

Fig. 5 represents diagrammatically one arrangement for carrying out the invention.

Fig. 6 is a diagram showing the relation between the rectier voltage and output current.

Figs. '7, 8, 9, l0 and 11 represent diagrammatically other arrangements for carrying out the invention.

Various arrangements have already been proposed or regulating electrical rectiers of the vapor electric discharge type with anodecontrol 5 grids, by utilizing a grid exciting voltage composed of an alternating voltage Eg of the same frequency as the anode Voltage, and a superposed continuous voltage Ego variable in relation to the cathode potential; see Fig. 1. The moment of ig- 10 nition of an anode is more or less retarded according to the value of the continuous component Ego oi the biasing voltage Egal which represents the resultant alternating potential of the grid in relation to the cathode potential. The corresponding anode l ignites when the grid potential reaches the value O, this being only approximately correct, but suiiicient for the present explanation. When the continuous component Egc:0, the anode l ignites at A, so that if the 2O vertical line ry passing through the natural point of ignition of the anode l be taken as axis of reerence for the angles of ignition, the ignition angle is represented by ao. Now if the continuous component YEole of the biasing voltage be given a certain value Elgc, regarded as positive when it tends to displace the resultant voltage curve Egal upwardly in the direction of the arrow, the ignition angle becomes alo which is less than an.

In particular, it has been sought to utilize this method of grid control in order to secure an automatic regulation of the continuous voltage Ec as a function of the output current Ic supplied by the rectifier, by variation of the continuous voltage Egc applied to the control grids, according to a definite law Egczfc).

It has been noted that in a vapor electric discharge rectifier with movable cathodic spot, which is the case for apparatus of large power, the blocking or biasing voltage for a given anode voltage is variable. It depends not only on the position of the cathodic spot, but likewise on the temperature of the rectifier (in particular on the temperature of the anodes), on the state of ionization of the vapor in the vicinity of the anodes, on the magnitude of the continuous current output and on the pressure. This inconvenience has the direct consequence that the regulation of the continuous voltage by the method mentioned 5o above loses all precision for the relationship Egc=f(Ic) which is imposed on the continuous voltage exciting the grid. The variation of the continuous voltage given by the rectier as a function of the continuous current output, shows a relation which is quite diierent from that which it is desired to obtain.

The present invention has for its object to remedy this inconvenience and to obtain any desired relationship either of the continuous voltage Ec to the load, or of the output eurent Ic to the continuous current power output, or of the current Ic to the current supplied by any other apparatus (whether ionized vapor rectiers or rotary machines) coupled in parallel with the rectiiier under consideration.

The grid control voltage is still constituted by an alternating voltage Ega, of the same frequency as the anode voltage, and a superposed variable continuous voltage Ego, but the latter can assume automatically such value as is necessary at a given moment for either the rectified voltage Ec or the continuous output current Ic to conform with the desired relationship. In this way the operation becomes independent of var1- ations of the grid blocking or biasing voltage.

Before entering into details of the invention, it may be explained that it is based upon the well-known properties of the three field winding exciter, as employed for example with continuous current traction motors and usually driven at constant speed. One of the exciter iield windings is always shunt and it is regulated in such a Way that its resistance line dlOd coincides with the straight part AlOA of the no-load char acteristic BIOB corresponding to the equation =f (n i), where e is the exciter voltage and n i the resultant ampere turns of field excitation; see Fig. 2.

For a more complete understanding of the invention, it is desirable to recall the principle of operation of an exciter of this kind. Fig. 3 represents an exciter E driven at constant speed by a suitable motor, not shown in the drawings. This exciter feeds an external circuit C, the precise nature of which may for the moment be considered as immaterial.

Let a be the shunt eld winding of the exciter E, and b and c two other iield windings which are subject to the condition that their respective ampere-turns act in opposition. If the winding a, has na turns, and is designates the current flowing in this winding, the shunt arnpere-turns are represented by na ia. If the winding b has nb turns, and it designates the current flowing in this winding, its ampere-turns are represented by nb it. Similarly, if the winding c has nc turns, and 'ic designates the current flowing in this winding, its ampere-turns are represented by nc ic.

Suppose that the following condition is fulfilled:-

nb ibznc ic (l) then owing to the regulation of the shunt iield as indicated above, and the equality of the opposing ampere-turns (nb it and ne ic), the voltage e which the exciter can produce is indeterminate For, considering the general equation, expressed in absolute values,-

Resultant ampere-turns:

(ne. in) +(nb ib) +(7lc ic) it follows from the previous Equation (l) that the point of operation of the exciter E may be located anywhere along the line AlOA in Fig. 2, whatever be the absolute value of nb it or 11C 1c.

Assume that at a given moment this point of operation is at F on the corresponding line AlOA in Fig. 4, and that for some reason there is an ilowing through the field winding c, this increase taking place without any delay or lag.

In these conditions the voltage e will not reach the point D because the Equation (l) will be re-established when the Voltage e reaches the point G for example, G being still located on the straight portion AlOA of the exciter characteristic. It will be understood that the possible variation of the exciter voltage e between the points A1 and A must be suiiicient for the complete regulation of the current ic, this requirement being only a matter of machine design.

It may be remarked, on the other hand, that in the conditions assumed, the point G is well deiined. In fact, if the voltage e took up another position at G1 near the point G, there 1i" would result an increase of the eld current ic and the Equation (l) Awould no longer be satisiied. According to the explanation given above, the voltage e will tend to move to the point G, the only one at which equilibrium is Jv possible.

Before proceeding further, it is necessary to note that no hypothesis has been set up as to the nature of the electrical connections which can exist between the circuit C and the winding c. It is desirable to remark however that in all the applications of the three-field winding ex citer hitherto suggested, the exciter controls the external circuit C in a purely electro-dynamic manner, which means that the exciter E acts by feeding into the circuit C a variable current 'ile determined by the equation:

where ec represents the back E. M. F. of the circuit C, Re the resistance of this circuit and e the voltage of the exciter E.

On the contrary, in the applications which are now to be considered, the circuit in which the exciter E is inserted possesses no back 5i E. M. F. balanced by the voltage c of the exciter. The function or" the latter consists in modifying the relative potential of a point in the control system C in a purely electrostatic manner, which is new in the art, of utilizing Jche three iield windi T ing exciter described above.

Fig. 5 represents one arrangement in which the principle of the three-field winding exciter is applied; this arrangement allows of maintaining constant the continuous voltage Ec of the rectifier, while the value of the output current Ic can vary between O and ICN (Fig.Y 6). In Fig. 5, R represents the ionized metallic vapor rectifier, having six anodes ar provided with control grids g; T represents the transformer feeding six-phase current to the anodes of the rectier; H represents the six-phase potential phase-shifter feeding the anode-control grids y by way of resistances r; E represents the auxiliary generator or exciter with three field windings a b and c; and S is a shunt-wound exciter feeding the iield winding b of the exciter E, the two machines E and S being coupled together mechanically and driven at constant speed by a suitable motor, not shown in the drawings.

The shunt'field winding a ofthe exciter E is regulated as already explained with reference to Fig. 2.

The separately excited iield winding b is traversed by a constant current at any given adjustment of the variable field rheostat rli of the exciter S.

The other field winding c is fed by the continuous voltage of the rectifier R.

The exciter E is to be connected between the cathode K of the rectifier and the neutral point O1 of the phase-shifter H.

Assume for the moment that the exciter E is omitted and that the neutral point O1 is connected directly to the cathode K. With the rectiiier giving no current output, the phase-Shiiter H is regulated to produce such a lag in the ignition of the anodes that the rectified voltage Ec shall be equal to ECN, that being the value of the continuous voltage given by the rectifier for the full normal output ICN according to the load-characteristic (see Fig. 6) of the transformer-rectifier group, when the grids are not energized; the angular displacement of the phase-shifter H will be designated an as already deiined with reference to Fig. 1.

With the exciter E still out of the circuit of the phase-shifter I-I, but the field winding c connected to the terminals of the rectifier R, the current ib in the separately excited field winding b is regulated by means of the rheostat rh so as to obtain equality of the two quantities ne ic and nb ib. The exciter E is then introduced into the circuit O1 K, as shown in Fig. 5; as already explained, the voltage e of the exciter must be nil. When a certain load is applied to the rectifier, the voltage Ec will tend to decrease according to its natural characteristic, so that the exciter iield current i@ will tend to decrease also; since the current ib in the separately excited field Winding b is maintained, the exciter E will begin to generate a voltage e which is applied to the control grids, causing a decrease of the anode ignition angle, ironi ao towards w10. The reduced ignition lag will bring about an increase of the voltage EC, causing it to resume the Value ECN at which ne ibznb ib. Similar action will take place at any point up to the maximum value ICN of the continuous current output.

It may be noted that there can be adopted a value of the angle ao different from that defined above, while yet retaining the same value for the iield current ib; for example the ignition angle at nil output current may be less than Ele diiferent from ECN.

" an and equal to alo; the exciter voltage e for nil output current (10:0), instead of being nil, will then assume a negative value, for example G (Fig. 4), determined in such a way that the rectified voltage Ec=Ec1v If the value of the field current ib is modified by regulation of the rheostat rh, the continuous voltage Eo will still be maintained constant, whatever be the load, but it will assume a value It will be seen therefore that the value of the voltage Ec remains constant at varying loads, and depends only on the value given tothe field current ib, which is kept constant at the selected value.

It is to be noted that the constant voltage Ec, given by this compound operation of the rectiiier becomes independent of variations in the alternating supply voltage feeding the transformer T. Overcompounding or under-compounding of the voltage Ec, as a function of the output current Ic, can be obtained by arrangements analogous with that of Fig. 5; it is in fact only necessary to p-rovide for the increase or the decrease of the separate excitation field current ib when the output current Ic increases. This can easily be arranged, for example by providing a supplementary neld winding upon the machine S, traversed by a current proportional to the output current Ic. The ampere turns of this supplementary field winding will be cumulative to the main iield winding in the case of over-compounding, and differential in the case of under-compounding; the degree of over or under-compounding can be regulated by varying the proportions of the two field windings on the machine S. A plain reversing switch for one of the iield windings will then allow of changing from over to under-compounding, and vice versa.

Any other meansfor producing a variation of the iield current ib as a function of the output Ic may be utilized for the same object.

A further application of the invention may be contemplated in which, instead of maintaining the voltage Ec constant, it is proposed to maintain the current constant when the power output varies. in this case, instead of connecting the field coil c of the exciter to the terminals of the rectifier, it is so arranged as to be traversed by a current equal to or proportional to the output current llc, as illustrated in rl, where L represents the continuous current system supplied by the rectifier.

If the field current ib supplied by the exciter S is constant, the current output Ic of the rectifier will be maintained constant and the voltage e of the exciter E will vary in magnitude and in sign so as to regulate the voltage Ec of the rectiiier according to the power required.

The angular displacement of the phase-shifter H is still assumed to be constant.

In order to modify the value of the output current Ic, it is only necessary to alter the value of the field current ib.

A combination of the two preceding arrangements allows for the parallel working of two or more rectiiiers, as well as any desired division of loading between those apparatus, whatever be the load-characteristics of the machines (overcompounded or under-compounded).

Fig. 8 represents two groups of transformerrectiiiers working in parallel. The iirst rectifier R1 is provided with means analogous with Fig. 5 for regulating its voltage Ecl as a function of its output current Ici for example maintaining its continuous voltage constant. The second rectifier R2 is provided with means for regulating its voltage E02 to maintain its output current Icz proportional to the current Ici supplied by the first rectiiier R1. in order to do this, the winding b of the exciter E2 for the second rectiiier R2 is traversed by a current proportional to the output current Ici of the first rectiiier. The distribution of the loads is regulated by means of adjustable resistanoes ri and r2. It will be seen that on one hand the voltage cf the first rectifier R1 will be maintained constant, as previously explained, and that on the other hand for a given power demanded by the supply system L, the exciter E2 of the second rectifier will decide the proportioning of the two output currents Ici and Icz according to the relation iixed by the adjustment of the resistances r1 and r2.

It has been assumed, in the case of Fig. 8, that the first rectier R1 (which may be regarded as the pilot rectifier of the sub-station) is provided with means for regulating its voltage Ecl.

It is evident that the parallel working of the rectifiers R1 and R2 could be carried out in the same way without the pilot rectier Ri being provided with means for regulating its voltage. The continuous voltage characteristic under load of the rectifier R1 would then be determined by the leakage reactances of its transformer.

Any desired number of rectiiiers controlled in this way may work in parallel; if this number be n, it suffices to arrange (1i-l) rectiers in a manner identica-l with that shown for R2 in Fig. 8, the other rectifier being the pilot rectifier R1,

The improved system of control will allow of obtaining with equal efficiency the parallel operation of two or more rectifiers fed by independent alternating current supply systems, the frequencies of which may even be different.

The control system may easily be extended to cover the operation of rectiers in parallel with rotary continuous current machines, of which the load-characteristics may be of any kind. The electrical diagram of such an arrangement would be analaogcus with Fig. 8, but having the rectifier R1 replaced by a continuous current generator of rotary type.

Fig. 11 illustrates an arrangement of this kind, in which the rectifier R is connected in parallel with a rotary machine Cr. which may be a converter group or a mechanical rectiiier. The rectifier R is provided with means analogous with Fig. 5 for regulating its continuous output current Ici while the generator G operates at conetant voltage to supply the system L. The separately excited eld winding b of the exciter E is traversed by a current proportional to the output of the generator G, taken across a shunt Sh; the other field winding c of the exciter is energized by the output current Ici of the rectifier R. It will be seen that for a given power demanded by the supply system L, the exciter E will decide the proportie-ning; of the output currents from the generator and rectifier respectively, the two field windings h c balancing when the two output curn rents are in the correct relation.

The parallel running of rectiiiers and rotary machines in the same sub-station may evidently be extended to the parallel working of two adjacent substations, of which one can be constituted in any desired manner, while the other is supposed to be constituted solely by rectiiiers of the vapor discharge type. The power required for the control of the grids being very small, it b ecomes possible.to have a single device for controlling the grids, all the grids being connected in parallel. In these conditions, the rectifiersubstaton be controlled by the other substation by means of an exciter arranged in accordance with the diagram already considered for the exciter E2 in Fig. 8; the currents circulating in the field windings b2 and c2 would be proportional respectively to the currents supplied by the two substations.

The invention may also be employed for the automatic connection of a rectifier to a supply system by means of a three field winding exciter in which the field winding b or c would be energized by the difference of potential between the voltage EN of the supply system and the voltage Ec of the rectifier which is to be connected thereto. The principle of this operation of the exciter is explained in the speciiication of U. S. application Serial No. 545,557, F. Lejeune, led June 19, 1931.

The arrangement represented diagrammatically in Fig. 5 for controlling the variation of the continuous voltage as a function of the load may be insuiiicient in some cases, from the point of view of precision. In fact, if it is desired to eifect the regulation of the continuous voltage Ec to within a few volts, it is necessary that with a small departure of the voltage Ec from the de sired value, there shall be produced ,a large variation of the ampere-turns ne is so that the correspending variation of the voltage e of the exciter E will likewise be large. For this reason, instead of making the ampere turns ne ic depend upon the voltage Ec, they may be made to depend upon the difference between the rectifier voltage Eo and another voltage ES, which may be termed the reference voltage, the sensitivity increasing as the difference (EcEs) approaches 0. If the difference (Ec--Es is made equal to 0, the current ib must be nil; the iield winding b therefore becomes unnecessary and it can be suppressed. In other words, the differential action of the two opposing fields b c is replaced by a single field excited by a differential voltage.

Fig. 9 represents the general diagram of this novel arrangement. As in Fig. 5, the exciter E is connected to the terminal of the cathode K on the one hand, and to the neutral point O1 of the phase-shifter H on the other hand. The machine E possesses two iield windings: a shunt winding o and an independent winding c, The exciter S is now placed in series with the field winding c of the exciter E, the whole being connected to the neutral point O of the transformer T on the one hand and to the cathode K on the other hand; the continuous voltage Es of the machine S is in opposition to the controlled voltage EC.

When EszEc, the current circulating in the winding c is equal to il. If Ec varies the winding receives a certain current ic of which the value and the direction depend on the difference of voltage (Es- 13(2), as well as on its sign, and on the resistance of the circuit O S c K. If the difference (Es-Ec) is greater than 0, the exciter E produces a voltage e, which, when the regulation is correct, tends to diminish the ignition angle a of the rectier anodes and therefore to increase the value of the voltage Ec, as has already been explained. On the contrary, if the difference (Ee-Ec) is less than 0, that is, negative, the field current ic being reversed, the voltage e changes sign and the inverse phenomenon is produced; the ignition angle a increases, causing the reduction in the value of the voltage Ec. It follows naturally from this arrangement that if it be desired to obtain an over-compounded or undercompounded characteristic of the continuous voltage Ec, as a function of the load, it suffices to modify the voltage Es of the machine S as a function of the output current Ic, as already explained.

For a given value of the difference of voltage (Es-Ec), the sensitivity of the system increases when the resistance of the circuit O S c K diminishes. This total resistance, which can be represented as X, can be reduced to as low a value as desired, by placing in series in the circuit O S c K a small dynamo-electric machine having a series-wound field and playing the part of a negative resistance.

li'ig. 10 represents arrangement analogous with that of Fig. 9, but provided in addition with a series motor Sl coupled mechanically to the extiters E and S. This machine Sl is connected in series with the exciter S and the independent field 'winding c of the machine E. The resistance X 75 represents the equivalent resistance of the circuit O S1 S c K. By suitable dimensioning and regulation of this machine S1 it is possible to produce at its terminals a voltage es of opposite sign and of the same absolute value as the drop of voltage (Xie) in the equivalent resistance X.

In conclusion, the use of the exciter having shunt and differential field windings in conjunction with the rectifier oi" the vapor electric discharge type, allows of obtaining any desired relation b-etween the continuous voltage and current supplied, and of ensuring the parallel working either of a plurality of such rectifiers with one another or of one or more rectiers with one or more rotary machines, in such conditions as may be desired.

In all cases it is possible to render the controlled apparatus independent ci their own characteristics and of any external variations (for example, of the alternating current supply systern) in order to impart to them the characteristic of a reference machine of very low power. This system is therefore Very iiexible, since it allows of substituting for the direct regulation of machines of large power, that of an auxiliary group of small size, which is much easier and more economical.

What I claim is:-

1. Means for regulating a vapor electric discharge device provided with an anode, a cathode and a control grid, and having alternating potentials applied between said anode and cathode and control grid, with a continuous voltage component superposed on the alternating potential between said control grid and cathode, comprising a dynamo-electric machine generating said continuous voltage component, a shunt eld winding for said machine, other eld-exciting means adapted to vary the total field excitation of said machine, and an independent source of current, said other iield exciting means being energized by said discharge device and said independent source of current, acting in opposition.

2. Means for regulating a vapor electric discharge device provided with an anode, a cathode and a control grid, and having alternating potentials applied between said anode and cathode and control grid, with a continuous voltage component superposed on the alternating potential between said control grid and cathode, comprising a dynamo-electric machine generating said continuous voltage component, a shunt eld winding for said machine, two other eld windings for said machine, said other eld windings acting in opposition to one another, and an independent source of current, said other field windings being energized respectively by the output voltage of said discharge device and by said independent source of current.

3. Means for regulating a vapor electric discharge device provided with an anode, a cathode and a control grid, and having alternating potentials applied between said anode and cathode and control grid, with a continuous voltage component superposed on the alternating potential between said control grid and cathode, comprising a dynamo-electric machine generating said continuous voltage component, a shunt field winding for said machine, two other iield windings for said machine, said other eld windings acting in opposition to one another, and an independent source of current, said other field windings being energized respectively by the output current of said discharge device and by said independent source of current.

4. Means for regulating a vapor electric discharge device provided With an anode, a cathode and a control grid, and having alternating potentials applied between said anode and cathode and control grid, with a continuous voltage component superposed on the alternating potential between said control grid and cathode, comprising a dynamo-electric machine generating said continuous voltage component, a shunt field winding for said machine, other field-exciting means adapted to vary the total field excitation said machine, and an independent directcurrent generator, said other field exciting means being energized by the output Voltage of said discharge device and the voltage of said directcurrent generator, acting in opposition.

5. The combination of a vapor electric discharge device provided with an energized anode, a cathode and a biased control grid, and a dynamo-electric generator supplying a continuous current component to bias said control grid, a shunt field winding for said dynamo-electric generator, other field windings for said dynamoelectric generator, said other field windings adapted to vary the total iield excitation of said dynamo-electric generator, and an independent source of current, said other field windings being energized by said discharge device and said independent source of current, acting in opposition.

6. In the art of vapor electric discharge devices, a dynamo-electricl generator supplying a continuous current component of the grid biasing potential, a shunt eld winding for said generator, two other field windings for said generator, said other eld windings operating differentially to one another, and an independent source of current feeding one of said other differentially operating field windings, the second of said other differentially operating eld windings being energized by the rectiied voltage of said discharge device.

7. In'the art of vapor electric discharge devices, a dynamo-electric generator supplying a continuous current component of the grid biasing potential, a shunt field winding for said generator, two other field windings for said generator, said other iield windings operating differentiaily to one another, and an independent source of current feeding one of said other differentially operating field windings, the second of said other differentially operating field windings being energized by the current output of said discharge device.

8. In the art of vapor electric discharge devices, a dynamo-electric generator supplying a continuous current component of the grid biassing potential, a shunt field winding for said generator, a separately excited iield winding for said generator, and an independent source of current, said separately excited field winding being energized by the difference between the rectified voltage of said discharge and the voltage of said independent source.

9. In the art of vapor electric discharge devices, a system of output regulation by variation of the continuous current component of the grid bias potential, comprising controlled generation of said component by a dynamo-electric machine having three eld windings, one being a shunt winding, and the other two acting in opposition being energized respectively by the output to be regulated and by an independent source of current.

l0. In the art of vapor electric discharge devices, means for regulating a plurality of discharge devices operating in parallel, comprising a dynamo-electric generator supplying a continuous current component of grid-bias potential for one of the discharge devices, a shunt field winding for said generator, two other field windings for said generator, said other field windings operating differentially to one another, one of said other field windings being energized by the output of said one discharge device, and the second of said other field windings being energized by the output of another of said discharge devices.

11. In the art of vapor electric discharge devices, means for regulating a plurality of discharge devices operating in parallel, comprising a plurality of dynamo-electric generators supplying continuous current components of gridbias potentials for the respective discharge devices, a shunt field winding for each of said generators, two other field windings for each of said generators, said other field windings of each generator operating differentially to one another, one of said other field windings of each generator being energized by the output of the respective discharge-device, and a separate dynamo-electric machine energizing the second of said other field windings of one of said generators, the second of said other field winding of each other generator being energized by the output of the rectifier corresponding to said one generator.

12. In the art of vapor electric discharge devices, means for regulating a discharge device working in parallel with a rotary machine generating continuous current, comprising a dynamoelectric generator supplying a continuous current component of lgrid-bias potential, a shunt field winding for said generator, two other field windings for said generator, said other field windings operating differentially to one another, one of said other field windings being energized by the output of said discharge device., and the second of said other field windings being energized by said rotary machine.

13, In the art of vapor-electric discharge devices, means for regulating the output comprising a dynamo-electric generator supplying a continuous current component of grid-bias potential, a shunt field winding for said generator, a separately excited field winding for said generator, and an independent shunt-wound generator, said separately excited eld winding being energized by the output voltage of the discharge device and the voltage of said independent generator, acting in opposition to one another.

14. In the art of vapor-electric discharge devices, means for regulating the output comprising a dynamo-electric generator supplying a continuous current component of grid-bias potential, a shunt field winding for said generator, a separately excited field winding for said generator, an independent shunt-wound generator, said separately excited field winding being energized by the output voltage of the discharge device and the voltage of said independent generator, acting in opposition, and a series-wound machine included in the circuit of said independent generator and separately excited field winding and operating as a negative resistance.

15. In the art of vapor-electric discharge devices, employed as rectiers for polyphase alternating current, means for regulating the moment of ignition of the anodes by variation of a continuous current component superposed on the alternating grid-bias potential, comprising a three field winding exciter supplying said continuous current component, said exciter having a shunt field winding and two separately excited field windings acting in opposition and normally balancing out, one of said separately excited field windings being energized by the output of the discharge device, and an independent source of current energizing the other of said separately excited field windings, any tendency to variation of said output affecting the normal balance of said separately excited field windings and causing said exciter to vary the continuous current component applied to the grids in the sense opposing said variation of output.

16. In the art of vapor electric discharge devices, means for regulating a discharge device operating in parallel with another source of continuous current, comprising a dynamo-electric generator supplying a continuous current component of grid-bias potential for said discharge device, a shunt field winding for said generator, two other field windings for said generator, said other field windings operating differentially to one another, one of said other field windings being energized by the output of said discharge device, and the second of said other field windings being energized by the output of said other source.

17. Means for regulating a vapor electric discharge device provided with an anode, a cathode and a control grid, and having alternating potentials applied between said anode and cathode and control grid, with a direct-current voltage component superposed on the alternating potential between said control grid and cathode, cornprising a dynamo-electric machine generating said direct-current voltage component, an independent source of direct current, and a plurality of field windings for said dynamo-electric machine, said field windings being energized by the voltage of said dynamo-electric machine., the voltage of said discharge device and the voltage of said independent source of direct current, respectively, and the voltage of said dynamo-electric machine producing shunt excitation and the other last-mentioned voltages acting in opposition to one another as regards the resultant excitation of said machine.

LOUIS LEROY.

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