US2008730A - Starting circuits - Google Patents

Description

July 23, 1935. L. SMEDE 2,008,730

STARTING CIRCUITS Filed May 3, 1933 2 Sheets-Sheet 2 WITNESSES: INVENTOR Z/k LZayd Smede.

dz BY Patented July 23,

PATENT OFFICE sraa'rmc amour-rs Lloyd Smede, Pittsburgh, Pa, minor to Westinghouse Electric & Manufacturing'company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 3, 1933, Serial No. 669,273 2': Claim. (01. 175-363) My invention relates to control apparatus and it has particular relation to control apparatus,

utilized in the operation of electric discharge devices oi the type incorporating a starting elec- 5 trode.

1 An electric discharge device of the type to which my invention particularly applies, in general, comprises a plurality of principal electrodes preferably enclosed in a gas-tight envelope between which an electrical discharge is to pass. The discharge may be initiated by impressing a potential of predetermined magnitude between the principal electrodes- However, in;the practice of my invention it is initiated by the cooperation of a starting electrode and one of the prin-- cipal electrodes. The starting electrode is disposed adjacent to or in contact with the principal electrode with which it is to cooperate and it generally has a resistance which is high compared to the resistance of the cooperative electrode. To start the discharge between the principal electrodes, a comparatively heavy current is transmitted between'the starting electrode and its cooperative electrode. 1

In the electric discharge devices that are utilized in the preferred practice of my invention,

at least one of the principal electrodes is a con ductive liquid or a suitable solidand the starting electrode is immersed therein. Whena solid is utilized it is preferably but not necessarily a metal of the type that has a relatively high vapor tension at a relatively low temperature such as lead or tin. I have found that the starting electrodes also cooperate in a suitable manner'with an electrode of 'iron or nickel although the vapor tension of such an electrode is not high.

More specifically, one of the principal electrodes in these electric discharge devices is mercury and the starting electrode is a rod of material having a resistivity high compared to mercury which is immersed in the mercury; To initiate a discharge between the principal electrodes of an electric discharge device of this type, a current is transmitted between the starting electrode and the mercury. This current is of such polarity that the starting electrode is positive electrically with respect to themercury.

While the theory of the operation of the elec-.

' electrode. It will appear at once from this consideration that to properly initiate the discharge, the starting electrode should'not be wettedby the mercury, nor should it amalgamate with the mercury. and, inexperimenting with the electric discharge devices discussed herein, I have verifled this conclusion.

However, among the materials that I have found which may be suitably utilized as starting electrodes are a number which have a heterogeneous internal structure as distinguished from 10 a homogeneous one. Such materialsare not uniformly electrically conductive throughout but the conductivity is provided by a series of conmay not amalgamate with it. As long as the strings of particles are unafiected by the mercury the starting electrode continues to function properly.

It will be seen from the above discussion that considerable care must be taken in selecting the electrodes that are 'utilized in the electric discharge devices and in providing for the transmission of a starting current between the starting electrode and the mercury. 'Since these currents are, in general, comparatively large, prob- 5 lems of considerable difilculty have arisen in providing the necessary starting apparatus. In accordance with the teachings of the prior art, the starting current is transmitted directly from the power source through the electrode in question. 40 However, since the electrode is deleteriously at ,fected by the reverse current which must necessarily pass therethrough when the discharge is initiated between the principal electrodes, a rectifier is ordinarilyconnected in series with the starting electrodes in thestarting circuit. The rectifier is so connected that it passes current only in a direction such that when it is energized, the startingelectrode is positive relative to'the mercury. When currentis thus trans- 5o mitted through the rectifier and through the starting electrode, a discharge is initiated be-, tween the principal electrodes. After the discharge is initiated, the rectifier prevents the passage of current through the starting electrode 56 by protects the electrode-from the deleterious ef-,

' fects of the reverse current.

in a direction such that the starting electrode is negative relative to the mercury, and there- In the discussion which follows the potential impressed between the principal electrodes of the electric discharge device shall be designated as the-principal potential. Correspondingly the current transmitted through the starting electrode to "initiate the discharge between the principal electrodes shall be designated as the starting current. Moreover, the potential of the mer- "cury shall be taken. as the reference potential.

Thus a positive principal potential is impressed on the electric discharge device when the mercury is negative electrically relative to the other principal electrode and a positive starting cur- 1 rent is transmitted through the starting electrode when the current flows from the-starting electrode to the mercury. The above set of con ventions are provided on the assumptionthat, as is the case in the preferred practice of my invention, the electric discharge device is or the asymmetric type and has one mercury electrode and'one anode to cooperate with the mercury electrode. If the device is of the symmetric type and has two mercury electrodes with each of 'rectifier. By reason of the variations in the elements appurtenant to the power source, the cur-" rent transmitted through the rectifier and through the starting. electrode is not, ingenerahuniform and in consequence thereof, in apparatus of the prior art, the output of the electric discharge device varies over'a considerable range;

It is to be understood that the starting electrode functions only to start the discharge be,- tween the principal electrodes. When starting current of proper polarity is transmitted between phed to provide for any contingency and the the starting electrode and the mercury, the discharge between the principal electrodes is initiated and it continues as long as the principal potential is of proper magnitude and polarity to sustain the discharge. The polarity should be such that the mercury is negative relative to the other principal electrode, while the magnitude of the principal potential should be equivalent to. the ionizing potential corresponding to the distancebetween the principal electrode and.

the character of the vapor in which the'electrode's are immersed. l

To attain satisfactory control of the output oftheelectric discharge device, the practice has been to connect an alternating potential between the principal electrodes of the electric discharge device. If analternating principal potential is provided, a discharge may, in general, be

initiated. between the electrodes only during the intervals when half cycles of positive principal potential are impressed on the electric discharge device. If a pulse of positive starting current of proper polarity is transmitted between the-starting electrode and the mercury during an interval when the principal potential is positive, a discharge is initiated between. the principal electrode and continues substantially during the remaining portion of the positive half cycle. The point in the positive half cycle of principal potential at which the discharge is initiated is dependent, t1- co'urse,'onthe magnitude of the current transmittedbetween the starting electrodeand the mercury, and on the particular instant at which the current attainsv the proper magnitude. If the 1 starting current varies over ,a wide range the current output of the electric discharge device device have rendered it rather unsatisfactory in its operation. Anotherdiificulty in the starting operation appears to arise from the character of the starting I electrode which, as has been explained above, is often made of aheterogeneous material, composed of a mass of stringy electrical conducting paths. These stringy paths terminate in the mercury and of these a number terminate in the region .of the \duced' into the output of the electric discharge meniscus of the mercury. that is adjacent tothe starting electrode.

nals of the paths that just contact the mercury become hot, causing the mercuryin their small spheres toevaporate. When the mercury evap' crates a minute gap is formed between the mercury and the ends of the conducting paths and arcs are ignited across the paths and cause the discharge between the principal electrodes to be initiated.

As the operation of the electric discharge device continues the terminals of the stringy conducting paths vary in dimension and location and by reason of this variation more or less current is required to initiate. the discharge. If the terminals of thestringy paths aresmall in dimensions the current required for starting is small; on the other hand, if the terminals are extensive in area the current required for startingis comparatively large. Ingeneral, sufiicient current must be supminimum starting current which should be supplied for proper operation should be large enough value to its maximum during an interval corresponding to a quarter-cycle of starting potential. If the terminals of the conducting strings are small in area, the necessary starting arc will be produced earlyin the quarter-cycle of starting current and the electric discharge device will become energizedje'arly in the quarter-cycle. If, on the other hand, the terminals are extensive infarea the electric discharge device will start late in the quarter-cycle. As the character of the starting electrode is varied during operation the current output of the electric discharge device will therefore vary continuously.

It is accordingly an object of my invention to provide for electric devicesof the type incorporating starting electrodes, starting apparatus for precisely and accurately controllingthe current output.

Another object of my invention is to provide for electric discharge devices of the type incor- Whenthe starting current is transmitted through the latter paths the termi- A further object of my invention is to provide for electric discharge devices of the type incorporating starting electrodes, apparatus for'applying starting currents of such high peak values as to definitely determine the point in the positive half cycle of principal potential at which 'the electric discharge device is to start, but of such short duration as to require conductors of comparatively small capacity for transmission.

vide for electric discharge devices of the type incorporating starting electrodes of heterogeneous internal structure, apparatus for applying a starting current impulw to the starting electrodesthat shall be of such short duration and the output of the electric discharge devices shall be uniform and shall be capable of accurate adjustment. I

In accordance with my invention, the recti fier through which the starting current istransmitted is energized from a capacitor which is, in turn, charged by direct current pulsations transmitted from an alternating current power source through a second rectifier. 'Th'e alternating potential impressed on the latter rectifier and the capacitor is in opposite'phase rela- I tionship to the alternating potential that is im-.

pressed on the principal electrodes of the elec-- tric discharge device. The electric discharge device is, in the preferred practice of my invention, of the asymmetric type, and when the po-- tential impressed-between its electrodes is of I such polarity that current is not transmitted electrode and the capacitor is connectedin series with its principal electrodes with the mercury electrode of the electric discharge device and with the starting electrode. As has been ex plained hereinabove, the capacitor is charged during a negative half cycle of principal potential of vthe electric discharge device. During .the

charging interval the potential impressed be-,

tween the control electrode and the principal electrodes of the rectifier associated with the starting electrode is maintained at such a value that 1 the rectifier is deenergized. The capacitor is 70.

charged during a fraction of the negative half cycle of principal potential and thereafter the potential impressed between the principal'electrodes of the rectifier associated with the start-. ,ing electrode is sufiicient to initiate a discharge between those electrodes. The potentialapplied between the-control electrode and the principal electrodes of the rectifier is so varied that the rectifier iscapable of becoming-energized at a point in the positive half cycle of principal po-' tential, of the electric .discharge device which corresponds to the'current output that is desired. When thecontrol potential of the rectifier attains the requisite value, the rectifier becomes energized and the capacitor is discharged through the'rectifier and-through the starting the electric discharge device.

In the following discussion the potential impressed between the control electrode and the cathode'of the rectifier shall be designated as the Still another object of my invention is to pro--.

control potential; The potential impressed between'the anode and the cathode of the rectifier shall be designated as the principal potential of the rectifier and by analogy with the electric discharge device the potential of the cathode shall be taken as'the referencepotential. Moreover, the control potential at any principal potential above which the rectifier is just energized and below which it remains deenergized shall be designated as the limiting control potential.

The capacitor and the rectifier through which the starting current is transmitted should be of such character that the current impulse transmitted through the starting electrode is sufficient to initiate the discharge between the principal electrodes, of the electric discharge device under'most circumstancesthat are met in prac- 1O electrode, and initiates the principal current in tice. For this reason, I have found that preferably the rectifier should be of the gas-filled type and the network including the rectifier, the capacitor and. the starting electrode should be of such character that to 100 amperes are transmitted through the starting electrode in a short interval of time during the starting operation. However, it should be noted that myinvention has been utilized in systems where the starting current required is as low as 7 milliamperes and in systenis in which the starting current required is greater than 100 amperes.

The novel features that I consider characteristic of my invention are set forth with particu-- larity in the appended claims. The invention itself, however; both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood when read in connection with the accompanying drawings in which:

Figure 1 is a diagrammatic view showing a pre- -bon, and a cathode 5, preferably of mercury, disposed in a chamber I that is preferably highly evacuated. A starting electrode 9 is immersed in the mercury 5.' As has been explained hereinabove, the starting electrode 9 should have a resistivity high compared to the resistivity of the mercury 5 and should not be wetted by the mercury nor should it amalgamate with the mercury. I have found that for proper operation the starting electrode 8 should-have a resistivity of at least 0.4 per cubic inch.

As can be seen from Fig. 1, it the startingjelectrade 9 is not wetted by the mercury 5 and does not amalgamate therewith the meniscus l I of the mercury in the region in which it is in contact with the starting. electrode recedes from the electrode and a minute gap [3 is provided between the mercury andthe starting electrode. According to the present theory of the operation of the electric discharge device i, when a starting current of proper polarity is transmitted between the starting electrode 9 and the mercury 5, minute sparks are generatedin the gap '13 between the meniscus andthe starting electrode, and by reason of the ionization produced by the minute sparks, the discharge between the prini3 between the mercury and the starting electrode will not be provided.

If, however, a starting electrode 9 of heterogeneous structure is utilized the mercury may wet the external surface of the electrode or amalgamate with it as has been explained hereinabove provided that it does not wet" or amalgamate with the ends of the individual stringy'conductors of which the starting electrode is composed. a I

It is to be understood, of course, that the above discussion is of a general theoretical character and may not, .when the situation is better known, be found to represent the actual conditions For'this reason it should be understood that myinvention is not to be limited by'any particular theory of operation. 5

As to the proper materials which smay be utilized for the starting electrodes .3, I havefound that carbon, silicate carbide,- boron carbide, boron, silicon boron. and boron carbide mixtures and boron and carbonmixtures, yield satisfactory results. From the present'state of my work with the electric discharge devices, it appears that carborundum (that is to say, silicon carbide) yields highly edifying results, and boron carbide, boron and mixtures of boron and carbon appear to be far more satisfactory even than silicon carbide.

To return to the apparatus shown inEig. 1, the electric discharge device i is supplied with potential from a suitable power source (not shown) through a transformer l5, one section 11 of the secondary l9 of which is connected between the anode 3 and the cathode 5 thereof through a load 21 of any general character that might be energized through the electric discharge device. v

The starting potential for the electric-discharge device is provided by a capacitor. 23' that is periodically charged from another section 25 of the secondary 19 through a rectifier 21 and is discharged through another rectifier 29 of the grid controlled type. The anode 31 of the grid controlled rectifier 29 is connected to one plate 33 of the capacitor23 while the cathode 35 is connected to the-starting electrode 9 of the electric discharge device I through a resistor-31 of suit- The other plate 39 of the capacithe electric discharge device I.

cuit of the grid controlled rectifler'29, 'the resistor- 31, the starting electrode Bjand its cotudes of the various elements.

operative mercury electrode 5 has a predetermined time constant depending on the magni- By varying-the resistor 31in series with the grid controlled recti.- fier 29 the time constant of the network 14 I may be varied. The time constant of the network 41' determines the rate at which the capacitor when charged is discharged through the network, and.

consequently determines when the principal'current in the electric discharge device -I will be initiated.

The resistor 37-15 utilized in the discharging network 4!, by reason of the fact that the starting current must be supplied for at least a small interval of time before the discharge between the principal electrodes. 3 and 5 is initiated. If the starting current does not persist for at least this interval of time the electric discharge device fails to become energized in spite of the magniwas of the starting current: The time constant of the starting network 41' is of such magnitude that the starting current persists for the necessary interval or time. The time interval is of course extremely small and in practice varies from 0 to 500 micro-seconds.

7 -25 The capacitor 23 is connected in series withv the rectifier 21 through which it is charged and with a resistor 63 of suitable character. The

cathode 35 of the rectifier 21 is connected to the plate 33 of the capacitor 23 to which the anode iii of the grid controlled rectifier 29is connected and the anode 41 of the rectifier is connected to one terminal 59 of the section 25 of the secondary l5 whereby the capacitor 23 is charged. The network5i including the section 25 of the secondary l9 through which the capacitor 23 is charged; the rectifier 21 through which it is charged, the capacitor 23 and the resistor 93', have a predetermined time constant which, in turn, determines the rate at which the capacitor 23 is charged.

The section 25 of the secondary 19 through which the capacitor 23 is charged is sowound that the potential impressed across the network is in opposite phase relationship to the principal potential impressed on the electric discharge de vice l and the potential impressed on the terminal .69 to which the anode d1 of the rectifier 21 is connected-is out of phase with the potential impressed .on the terminal 53 to which the anode 3 of the electric discharge device I is connected. Consequently when the potential of the anode .3 of the electric discharge device 1 is negative relative to the potential of the mercury cathode 5, the anode 41 of the rectifier 21 through which the capacitor 23 is charged is positive relative to its cathode t5, and current is transmitted through the rectifier 21 to charge the capacitor. It will be seen that as long as the anode 3 of the electric discharge device 1 is negative the device The control electrode 55 of the grid controlled rectifier 29 is connected to the anode 3 of the electric discharge device I through'aportion of the windings of a potentiometer 51, a suitable resistor 59 and the load 21. The potentiometer 51 is energized from a battery 60 and the potential of the control electrode 55 is in the preferred practice of, my invention maintained the half cycle oi principal potential I J a,oos,7so' negative relative to the cathode 3 of the rectifier ,29. By thus maintaining the control potential or the rectifier 29 negative the rectifier is main--- tained deenergized during;any desired traction of thefhalt cycles of principal potential that are 1111- pressed on the electric discharge device I.

feter I1 and the sum of these two negative potentlals is, in general, sufilcient to make certain that the grid controlled rectifier 29 is deenergized during the interval during which the negative hall waveoiprincipal potential is impressed on the electric'discharge device I; However, when the positive half wave of principal potential is impressed on the electric discharge device I, the,

potential impressed by the secondary section .I'I between the control electrode 55 and the cathode ll of the grid controlled rectifier 29 becomes increasingly positive and the negative potential provided by the potentiometer 5'I'is decreased until such a value oi. control potential is attained that the rectifier 29 becomes energized. It-is to be observed that since in practice the grid controlled rectifier 29 is preferably of the gas-filled type it passes abruptly from a deenergized condition to a fully energized condition. I

The grid controlled rectifier 29 is thus energized after the capacitor 23 has been chargedand the charge onthe. capacitor is transmitted theremission of the current through thestarting electrode 9 a discharge is initiated in the electric discharge device andpersists substantially until passes through a. zero value and becomes negative.

The operation of the system is illustrated in Figs. 2 and 3. The positive half wave of principal potentialisrepresented by the upper ruin line curve 5| in each graph. The potential to which the capacitor 23 is charged through the rectifier 21 associated therewith is represented by the horizontal line 63 that is' parallel to the axis of abscissa 65 in each graph. The control potentials at which the, grid controlled rectifier 29 becomes energized for values of principal potential corresponding to the principal potential of the electric curve 9|. In accordance with the foregoing nomenclature the curve 61 may be designated as the limiting control potential curve. The limiting control potential corresponding to the potential impressed on the capacitor is represented by a straight line 59parallel to the axis of abscissa and intersecting the limiting control potential curve 91 at the point II that corresponds to the potential impressed on the capacitor 23. The line 99 may be regarded as the limiting control potential curve for the gridvoontrolled rectifier when the capacitor is charged to a value represented by the upper horizontal line 63. The negative control potential that is normally impressedbetween the control electrode 55 and the .cathode '35 of the rectifier 29 bythe potentiometer 5! is represent- 1 ed by the lower horizontal line 13 in each plot.

- when a positive hali wave of principal potential is impressed on the electric discharge device l-the'control potential impressed on the grid control rectifier" is represented by the broken line.

curve Tl which, it will be noted, is simply the upper full line curve 8| representing the principal potential impressed on the electric discharge device I added to the lower horizontal line 13 representing thenegative control potential provided by the potentiometer 51. The grid controlled rectifier 29, and consequently the electric discharge device I, are energized approximately'at a point corresponding to the point ll of intersection of the broken line curve 15 and the horizontal line 99 representing the limiting control potential for the grid controlled rectifier 29. The electric discharge device i then remainsenergized during the remaining portion oi! the positive half cycle. The interval during whichthe electric discharge device I remains energized is represented by the shaded region I9 under the principal potential curve 5|. l

The graphs shown in Figs. 2 and 3 correspond to two difierent values of negative control potential, provided by the'pot'entiometer 51. As can be seen in the system represented by the curve shown in Fig. 3, the negative control potential is greater than in the system represented in Fig. 2,

and, consequently, the electric discharge device I is energized later in the cycle-ina system Such as is represented in Fig. 3 than it is in a system such as is represented'in Fig. 2.

Attention is called to the fact that with a system suchas is shown in Fig. 1 the output of the electric discharge device can only be controlled for the first half of the half cycle of positive principal potential. The limiting condition is represented by-a situation in which the potentials are 01 such value that the broken line curve 15 is tangent to the straight line 69 representing the limiting control potential of the grid controlled rectifier 29.

To attain control during the complete half cycle oi. principal positive potential 3. system such as is shown in Fig. 4 is provided. In this system,

associated with the electric discharge device I are substantially the same as the corresponding networks and circuit 01' the system shown in Fig. 1. However, the controlcircuit for'the grid controlled rectifier 29 is radically diiferent from the grrelsponding circuit of the system shown in 8. 1 An additional section 93-01? the secondary l9 of the power supply transformer 15 is provided.

The center tap 85 of the secondary section 83 is connected to the anode'3l of the grid controlled rectifier 29 through a. suitable resistor 91'. The terminal taps 89 and 9l of the section 83 are connected to the terminals of a phaseshifting network 93 comprising a variable resistor 9 5 and a capacitor 91 connected in series with each other. The junction point 99 of the resistor 95 and the capacitor 9'! is connected to the control electrode 55 of the grid controlled the capacitor 91 relative to the potential impressed between the terminal taps 89' and 9.l of the secondary section 83 may vary from zero to.

180 as the magnitude of the resistor 95 is varied and correspondingly the phase of the potential impressed between the control electrode 55 and the other electrodes 3| and35 for the grid con trolled rectifier 29 is varied relative to the other potentials in the system in the samemanner- The phase-shifting section 83 of the secondary i9 may be wound in the same manner as the section I! of the secondary l9 whereby principal po-' tential is supplied to the electric discharge device I. Consequently, by varying the resistor in the phase-shifting network of the system, the phase of the control potential may be shifted relative to the principal potential through an angle of 180. The operation of the system 'isillustrated in Fig. 5 in which the principal potential of the electric discharge device I, the principal potential .of the rectifier, the'limiting' control potentials of the grid controlled rectifier 29 andzthe negative control potential impressed on the grid controlled ,rectifier 29 are represented in the same manner as the corresponding elements of the system shown in Fig. 1 are represented in Figs. 2 and'3l The control potential is represented by a broken line sine curve Nil built up on the horizorital line 13 representing the negativecontrol potential. As canbe seen the "broken line curve IDI intersects the limiting control potential curve 69 at a point I03 which as far as its time coordinate is concerned lies in the latter half of the positive half cycle or principal potential impressed on the electric discharge device. The electric discharge device i is, therefore, energized at this point and remains energized during an interval represented by the shaded area 19 under the principal potential curve IS. a

In the system of the type shown in Fig. 1 that I have found particularly useful, the electric discharge device I is of the type substantially as shown in Fig. 1 and incorporates a mercury cathode 5, a nickel anode 3, and a starting electrode 9 of boron and boron carbide mixture of which the resistivity is at least .04 ohmpercubic,

inch and which has a heterogeneous stringy structure. The output potential of the section 25 of the secondary l9 whereby the capacitor 23 is charged is of the order of several hundred volts The rectifier 21 through which'the capacitor 23 is charged is of the gas filled type and is known as the Westinghouse KI-626. The capaciter 23 may vary from .1 microfarad to 16 microfarads, depending on the condition of the starting electrode9. The grid controlled rectifier 29 is of the type known as the Westinghouse KU+628. The resistor 31 in the discharging network ,ll of the capacitor 23 may vary from 2 to 10 ohms. I The resistor 59 in series with the control electrode 55 of the grid controlled rectifier 29 andthe potentiometer 51 associated therewith is of. the order of 25,090 ohms. The principal potential impressed on the electric .discharge device I is of the order of volts. My invention has been shown. herein as ap plied to particular systems.- Specifically, it has been shown 'as applied to systems in which the electric discharge device transmits only the positive half wave of principal potential impressed thereon. Its application to full wave rectifying systems is apparent. In such systems the simplest procedure is to apply the same elements to the negative half of the wave of pr'incipa1 potential as are applied to the positive half wave of principal potential and to properly connect the .elements of the system for this purpose.

In certain electric discharge devices con-'- structed in accordance with the teachings of the early prior art the discharge is initiated by im-- pressing a potential between the starting electrode and one principal electrode which are nor-- mally incontact with each other and then by separating the electrodes to produce a spark.

Insofar as my invention applied to devices of this type, it is to be regarded as including within its vices.

Finally it is to be notedthat in certain applications of my invention 'the 'rectifier' 21 in the charging network 5| may b omitted. While in.

certain connections I have ound that the rectifier 21 may be omitted in-apparatus (in which applied in phase with, the principal potential of the electric discharge device. In apparatus of this type the capacitor 23 having been charged negatively is discharged and charged positively during a fractional period'of the positive half cycle of principalp'otential. It is then discharged through the starting electrode 9 during a second interval of the positive half cycle of principal potential. During the negative half cycleof principal potential the capacitor 23 'is charged negatively and the following half cycle of positive principal potential is discharged and recharged positively through the windings of the secondarylsection 25 whereby the charging potential is supplied.

Although I have shown and described certain specific embodiments ofmy invention, I am fully "aware that many modifications thereof are possible. My invention, therefore, is not to be re-- stricted except insofar as is necessitated by the prior art and by the spirit claims.

I claim as my invention? v 1. In combination with an' electric discharge device of the type incorporating a plurality of of the appended principal electrodes between which an electric discharge is to pass and a starting electrode disposed adjacent to one of said principal electrodes for initiating said discharge; a capacitor, means for charging said capacitor and means, including a second electric discharge device coupled between said capacitor and said starting electrode I and providing a discharge path for said capacitor,

for coupling said capacitor, after it has been charged, to saidstarting electrode and said principal electrode adjacent thereto thereby so to discharge said capacitor that a/pulse' of current is transmitted through said starting electrode and the electric discharge between said principal electrodes is initiated. 1

7-2. In combination with an electric discharge device of the type incorporating a plurality of principal electrodes between which an electric discharge is to pass and a starting electrode disposed adjacent to one of said principal electrodes for initiating said discharge;' a capacitor, means for charging said capacitor and means, including a second electric discharge device having a con- 15 scope of equivalents, applications to these deelectric discharge between trol electrode and a plurality oi. principal electrodes, means for coupling said principal electrodes between said capacitor and said starting electrode to provide a discharge path for the charge on said capacitor and means for coupling said control electrode to the principal electrode of said first-named electric discharge device that is most remote from said starting electrode, for coupling said capacitor, after it has been charged, to said starting electrode and said principal electrode adjacent thereto thereby so to discharge said capacitor that a pulse of current is transmitted through said starting electrode and the said principal electrodes is initiated.

3. In combination with an electric discharge device or the type incorporating a plurality of principal electrodes between which a discharge is to pass and a starting electrode disposed in contact with one of said principal electrodes to cooperate therewith to initiate said discharge; means for storing electrical charges, means for charging said storing means, and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrode and said principal electrode in contact therewith and a discharge between said principal electrodes is initiated.

4. In combination with an electric discharge device of the type incorporating a plurality of principal .electrodes between which a discharge is to pass and a starting electrode having an electrical resistance that is high in comparison with the resistance of one of said principal electrodes disposed in contact with said principal electrode, and means for impressing an electrical potential between said principal electrodes to cooperate with said starting electrode to initiate and main tain said discharge between said principal electrodes; means for storing electrical charges, means for charging said storing means, and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse oi! current is transmitted through said starting electrode and said principal electrode in contact therewith and a discharge between said principal electrodes is initiated.

5. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass and means for initiating said discharge, said means including a mercury electrode and an electrode immersed in said mercury; means for storing electrical charges, means for charging said storing means and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said mercury and said electrode immersed therein and said discharge between said principal electrodes is initiated.

6. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass and means for initiating said discharge, said means including an electrode having a relatively low electrical resistance and an electrode having relatively high electrical resistance in contact therewith, and means for impressing an electrical potential between said principal electrodes to maintain said discharge; means for storing electrical charges, means for charging said storing means, and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse oi. current is transmitted through said starting electrode and said electrode in contact therewith and said discharge between said principal electrodes is initiated.

'7. In combination with an electric discharge device of the type having a plurality of principal .ectrodes between which a discharge is to pass, said electrodes being of such character that a discharge can only pass therebetween when a potential of one polarity is impressed therebetween and cannot pass therebetween when a potential oi! the opposite polarity is impressed therebetween, and means for initiating said discharge, said means including an electrode having a relatively low electrical resistance and an electrode having relatively high electrical resistance in contact therewith, and means for impressing an alternating electrical potential between said principal electrodes to maintain said discharge; means for storing electrical charges, means including means for impressing a potential across said storing means, for charging said storing means, said means including a plurality of terminals and means for impressing an alternating potential substantially in opposite phase to the potential impressed across said principal electrodes across said terminals, and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrode and said electrode in contact therewith and said discharge between said principal electrodes is initiated.

8. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass, said electrodes being of such character that a discharge can only pass therebetween when a potential of one polarity is impressed therebetween and cannot pass therebetween when a potential of the opposite polarity is impressed therebetween, and means for initiating said discharge, 4

said means including an electrode having a relatively low electrical resistance and an electrode having a relatively high electrical resistance in contact therewith, and means for impressing an alternating electrical potential between said principal electrodes to maintain said discharge; means for storing electrical charges, means, including a plurality of terminals, means for impressing an alternating potential substantially in opposite phase to the potential impressed across said principal electrodes across said terminals, current rectifying means and means for connecting said storing means to said terminals through said current rectifying means for charging said storing means, and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrode and said electrode in contact therewith and said discharge between said principal electrodes is initiated.

9. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass, said electrodes being of such character that a discharge can only pass therebetween when a potential of one polarity is impressed therebetween and cannot pass therebetween when a potential of the opposite polarity is impressed therebetween, and means for initiating said discharge,

8 acoavso said means including an electrode having a relatively low electrical resistance and an electrode having a relatively high electrical resistance in contact therewith, and means for impressing an alternating electrical potential between said principal electrodes to maintain said discharge; means for storing electrical charges, means, including a plurality of terminals, means for impressing an alternating potential substantially in opposite phase to the potential impressed across said principal electrodes across said terminals, current rectifying means and means for connecting said storing means to said terminals through said current rectifying means, for charging said storing means, and means including a second electric discharge device coupled between said starting electrode and said electrode in contact therewith, for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrode and said electrode in contact therewith, and said discharge between said principal electrodes is initiated.

10. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass, said electrodes being of such character that a discharge can only pass therebetween when a potential of one polarity is impressed therebetween and cannot pass therebetween when a potential of the opposite polarity is impressed therebetween, and means for initiating said discharge, said means including an electrode having a relatively low electrical resistance and an electrode having a relatively high electrical resistance in contact therewith, and means for impressing an alternatingelectrical potential between said principal electrodes to maintain said discharge; means for storing electrical charges, means, including a plurality of terminals, means for impressing an alternating potential substantially in opposite phase to the potential im-- pressed across said principal electrodes across said terminals, current rectifying means and means for connecting said storing means to said terminals through said current rectifying means for charging said storing means, a second electric discharge device having a control electrode and a plurality of principal electrodes, said device being of the type that has a deenergized condition when potentials of predetermined values are impressed between its principal electrodes and its control electrode and its principal electrodes and an energized condition when other predetermined potentials are impressed between its electrodes, and is capable only of abrupt transition from one condition to the other when the potentials impressed between its electrodes are varied, means for coupling said control electrode and one of said principal electrodes between the principal electrodes of said first-named electric discharge device, and means for coupling said principal electrodes of said last-named electric discharge device between said storing means and said electrode of relatively high resistance of said discharge initiating means to maintain said electric discharge device deenergized while the polarities of the potentials impressed by said potential impressing means are such that said storing means is charging and for energizing said last-named electric discharge device to discharge said storing means, after it has been charged, said coupling means being of such character that when said storing means is discharged,

a pulse of current is transmitted through said starting electrode and said electrode in contact therewith, and said discharge between said principal electrodes of said first-named electric discharge device is initiated.

11. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass and means for initiating said discharge, said means including a mercury electrode and an electrode immersed in said mercury; said electrode being of a type such that it does not amalgamate with mercury nor is it wetted thereby; means for storing electrical charges, means for charging said storing means and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said mercury and said electrode immersed therein and said discharge between said principal electrodes is initiated.

12. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass, and means for initiating said discharge, said means including a mercury electrode and an electrode comprising a rod of carborundum immersed in said mercury; means for storing electrical charges, means for charging said storing means and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said mercury and said electrode immersed therein, and said discharge between said principal electrodes is initiated.

13. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass and means for initiating said discharge, said means including a mercury electrode and an electrode immersed in said mercury; means for storing electrical charges, means for charging said storing means and means including a network having a predetermined time constant incorporating as an element thereof said storing means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said mercury and said electrode immersed therein and said discharge between said principal electrodes is initiated.

14. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass and means for initiating said discharge, said means including a mercury electrode and an electrode comprising a rod of boron carbide immersed in said mercury; means for storing electrical charges, means for charging said storing means and means for discharging said storing means,

after it has been charged, said discharging means being so coupled to said starting electrode that a, pulse of current is transmitted through said mercury and said electrode immersed therein, and said discharge between said principal electrodes is initiated.

15. In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass and means for initiating said discharge, said means including a mercury electrode and an electrode comprising a rod of boron immersed in said mercury, means for storing electrical charges, means for charging said storing means and means for discharging said storing'means, aiter'it has been charged, said discharging means being so 6 coupled to said starting electrode that a pulse of current is transmitted through said mercury and said electrode ,immersedtherein and said discharge between said principal electrodes is initiated.

16. In combination with an electriadischarge device of the type having a'plurality'of principal electrodes between which a discharge is, to pass and means for initiatingthe discharge, said means including a liquid electrode and 'an elec- 16 trode composed of a heterogeneous mass of stringy conductors immersed in said liquid; means for storing electrical charges, means for charging said storage means and means for discharging said storing means after it has been 20 charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said liquid and said electrode immersed therein, and a discharge between said principal electrodesis initiated. g

17. In combination with an electric discharge device of the type incorporating a plurality of principal electrodes between which a discharge is to. pass, at least one of said electrodes being mersed in said liquid to cooperate therewith to initiate a discharge; means for storing electrical charges, means for charging said storing means and means for discharging said storing means, after it has been charged, said discharging means 85 being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrode and said liquid'and a discharge between saidprlncipal' electrodes is initiated.

- 18. In combination with an electric discharge device of the type incorporating a plurality of principal electrodes between which a discharge is to pass, at least one of said electrodes being normally a liquid, and a starting electrode immersed in said liquid to cooperate therewith to initiate a discharge; said starting electrode being of a type such that it does not amalgamate with said liquid andis not wetted thereby; means for storing electrical charges, means for charging said storing means and means for discharging said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrode and said" liquid and a discharge between said principal electrodes is initiated.

19. In combination with an electric discharge device of the type incorporating a plurality of principal electrodes between which a discharge is to pass, at least one of said electrodes being normally a liquid, and a starting electrode immersed in said liquid to cooperatetherewith to initiate a discharge, said starting electrode being of a type such that it is not wetted by said liquid; means for storing electrical charges, meansfor charging said storing means and means for discharging'said storing means, after it has been charged, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrodes'and said liquid, and a discharge between said principal electrodes is initiated.

20. In combination with an electricdischarge is to pass, at least one of said electrodes being normally a liquid, and a starting electrode im-' ,the resistivity of the liquid; means for storing" 5 electrical charges, means for char i g said stor-.

- ing means and means for discharging said storing means, after it has been charged,'said discharging means being so coupled to said starting electrode that a pulse of current is transmitted throughsaid starting electrode and said liquid and a discharge between said principal electrodes is initiated.

21'; In combination with an'electric discharge device of. the type incorporating a plurality of 15 principal electrodes between which a discharge is top'ass, at leastone of said electrodes being normally a liquid, and a starting electrode immersed in said liquid to cooperate therewith to initiate a discharge, said starting electrode having a resistivity that is high in comparison with the resistivityof the liquid, is incapable of amalgamating with said liquid and is not wetted by said liquid, means for storing electrical charges, means for charging said storing means and means -for discharging said storing means, after it has .of current is transmitted through said starting electrode and said liquid, and a discharge between said principal electrodes is. initiated.

22; In combination with an electric discharge device of the type having a plurality of principal electrodes between which a discharge is to pass, at least one of said electrodes being mercury, and a starting electrode immersed in said mercury; means for'storing electrical charges, means for charging said storing means and means for discharging said storing means, said discharging means being so coupled to said starting electrode that a pulse of current is transmitted through said starting electrode and said mercury and a discharge between said principal electrodes is initiated.

23. In combination with an electric discharge device ofthe type having a plurality of principal electrodes between which a discharge is to pass and means for initiating said discharge, said means including a mercury electrode and an electrode of a material having a resistivity high in comparison with the resistivity of mercury immersed in said mercury; means for storing electrical charges, means for charging said storing 'means and means for discharging said storing means, after it has been charged, said discharging means-being so coupled to said starting electrode that a pulse of current is transmitted through said mercury and said electrode immersed therein and said discharge between said principal electrodes is initiated.

24. The method of initiating a discharge between the principal electrodes of an electric discharge device of the type incorporating a plurality of principal electrodes and at least one starting electrode, said starting electrode being 65 disposed in contact with one of the aforementioned principal electrodes, by means of apparatus which includes a capacitor and means for charging and discharging said capacitor, said method comprising charging said capacitor and passing a current between said starting electrode and the last-mentioned electrode, by discharging said capacitor through the last said electrodes after it has been charged, the maximum magnitude of said current being large enough to ini- Itiat'e the discharge between said principal electrodes during an interval of time that is so short that the elements through which said starting current is passed are not deleteriously aflected.

25. In combination with an electric discharge device of the type incorporating a plurality of principal electrodes between which a discharge is to pass and means for initiating the discharge including a plurality of electrodes disposed in contact with each other; a capacitor, means i'or charging said capacitor and means, including a second electric discharge-device in series circuit with said capacitor and said last-named electrodes, for coupling said capacitor, after it haslieen charged, to said last namedelectrodes thereby to discharge said capacitor between said last! namedelectrodes and to initiate the discharge between said principal electrodes.

26. In combination with an electric discharge deviceof the type incorporating a plurality of principal electrodes between which a discharge is to pass and means for initiating the discharge ineluding a plurality of electrodes disposed in contactlwith each other; a capacitor, means -ior charging said capacitor and means for connecting said capacitor in a network with said last-named electrodes, the last said means including means for maintaining said network electrically nonv conductive while saidcapacitor is charging and until it has been charged to' a predetermined "diti'erence o1 potential'and means Ior rendering said network electrically conductive after said capacitor has been charged to said predetermined diicharging said capacitor and means for connect- :ing said capacitor in a network with said lastnamed electrodes, the last said means including means for maintaining said network electrically non-conductive while said capacitor is charging and until it has been charged to a predetermined difierence of potential and means, responsive to the difference of potential impressed on said capacitor, for rendering saidnetwork electrically conductive after said capacitor has'been charged to said predetermined diflerence of potential whereby said capacitor is discharged between said last-named electrodes and the discharge between said principal electrodes is initiated DISCLAIMER 2,008,730.-Lloyd Pittsburgh Pa. Smhmo Cmcm'ra. Patent dated July 23 '1935. aimer filed ovember 12 1943 by the assignee Westinghm'm Elam a; Manufacturing com an Hereby enters this disclaimer to claim 1 of the-patent.

[Qfl'ieial Gazette December 7, 1948.]

DISCLAIMER 2,008,730.--Lloyd Smegea PittsburghNPa. smma Cmctm's. Patent dated July 23, '1935. D aimer filed ovember 12, 1943, by the aaaignee, Weatinw house Electric do Manufacturing Company.

Hereby enters this disclaimer to claim 1 of the-patent.

[Qfi'icial Gazette December 7, 1948.]

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