US1734917A - Electric discharge device - Google Patents

Description

NOV- 5, 1929. F. w. PEEK, JR

ELECTRIC DISCHARGE DEVICE Filed Deo. 27, 1928 Inventor' I F`r nk W. peek Jr'.,

b9 Y ba/ His' Attorney.

Pla-m1 Nwe, lezel UNITED STATES PATENT' OFFICE FRANK W. PEEK, J'R 0F PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW 'YORK t ELECTRIC DISCHARGE DEVICE Application led December 27, 1928. Serial No. 328,752.

My invention relatespto electric discharge devices. More particularly it relates to discharge devices of a type which is especially adapted for use for.` impulse generators. In

6 electric devices of this character, condensers are used and means are provided for first charging the condensers in multiple from a suitable source of current and thereafter discharging the condensers in series over a suitable circuit to produce the impulse. Prior to my invention, the source of charging current was of the* direct current type, which, up to the present, has presented certain limitations, so that the impulse voltage has been comparatively small.

It is an object of my linvention to provide an improved impulse generator, an object to Aprovide an impulse generator in which the condensers are charged in multiple directly from an alternating current source, such as a transformer. of the invention will be more fully understood from the following specification and claims, reference being had to the accompanying drawing, in which Fig. 1 shows, diagrammatically, a form of impulse generator embodying the principles of my invention, the generator shown in this ligure being what may be termed a three-stage generator, in which three condensers take part in producing the impulse discharge; and Fig. 2 shows diagrammatically another form of impulse generator embodying the principles of my invention. In Fig. 2 the solid lines show circuits corresponding to a three-stage generator, in which only three condensers take part in the discharge; while the dotted lines, taken together with the solid lines, show a four-stage generator, in which four condensers are used.

Referring to the drawing, Fig. 1, an alternating current generator A is shown connected with a transformer B. Connected in series with the secondary winding of this transformer are three branch circuits, one containing a non-inductive resistance element 2, a condenser 3, an inductance element 4, and a non-inductive resistance element 5. These elements 2, y3, 4 and 5 are all connected in series. A second one of the branch cir- It is also The nature may break down before the other.

cuits comprises a non-inductive resistance element 6, a condenser 7, an inductance element 8, and a second non-inductive resistance element 9. These elements 6, 7, 8 and 9 are also connected in series.- The third branch circuit comprises in series a non-inductive resist-ance elementlO a condenser 11, an inductance element 12, and a noninductive resistance element 13. With reference to the elementsl 2, 5, 6, 9 and v10, it will be understood that their impedance is high ascompared with that of the elementi 13, which latter is located in the series circuit and must therefore be comparatively low.

As shown in Fig. 1, the rst branch circuit is shunted by a spark gap 15; the second branch circuit is similarly shunted by a spark gap 16, and the third branch circuit is shunted by a spark gap 17. The spark gaps 15, 16 and 17 are so set that when the charging wave reaches a given voltage, all of the gaps spark series circuit, a voltage is developed across the terminals 20 and 21 of the element 13 which may be as high as approximately the sum of the voltages ofthe condensers 3, 7 and 1,1. l

While I have specified that the spark gaps 15, 16 and 17 may discharge simultaneously, this is not essential inasmuch as one spark .qa o In any event, the lsparks are maintained so that all of the gaps are short-circuited during a given interval of time, thereby establishing the series impulse circuit through the impedance element 13 with the result that a difference of potential developes across v'the terminals 20 and 21 of the velement 13 which may approximate the sumof the voltages of the condensers 3, 7 and 11. Therefore, if the voltage of the secondary of the transformer is 1000 kv. the

potential across the terminals 2O and 21 may` e in the neighborhood of 3000 kv. The voltage, however, may be much less than the sum of the condenser voltages, depending upon the shape of the wave as determined by the capacitance, resistance and inductance of the circuit. Therefore, the variable transient voltage is the sum of the condenser voltages decreased by a factor depending upon the shape of the wave in the series circuit as determined by the capacitance, resistance and inductance constants of the series circuit.

It will also be understood that while the gaps may be set to spark over at the maximum or crest voltage of the charging current wave, this'need not be so inasmuch as the gaps may be set to discharge aty different voltages, depending upon the impulse voltage desired across the terminals 20 and 21.

While I have represented the inductance elements 4, 8 and 12 as being distributed in the series circuit next to the condensers 3, 7 and 11, respectivel this inductance may be otherwise arranged. For example, the elements 4 and 8 may be omitted and the inductance value of the element 12 may be increased so as to be equaly to the sum of the inductances 4, 8, and 12. Furthermore, these 'elements may be inserted at any convenient point or points in the circuit.

Referring now to the impulse generator in` Fig. 2, this generator diifersfrom the one in Fig. 1 in that the impedance elements corresponding to the elements 2, 6 and 1() instead of being connected in multiple with the conductor that leads to the terminal 26 of the transformer, are connected in series with this terminal. As indicated, in this ligure the source of supply is the dynamo A and the transformer B. The circuit is provided with three branches, one branch comprising the non-inductive impedance element 22, the condenser 23, inductance 24, and non-inductive impedance 25, which elements are all connected in series across the terminals 26 and 27 of the transformer B. Another branch circuit comprises a pair of non-inductive impedance elements 28 and 29 in series with condenser 30 and with inductance 31. This-branch circuit 1s also in series with the secondary winding of the transformer. The third branch circuit comprises the non-inductive impedance elements 32 and 33 in series with the condenser 34 and inductance 35. This branch circuit is also in series with the secondary winding of the transformer. As shown in the drawing, the first branch circuit is provided with a bridging gap 36, the second branch circuit with a bridging gap 37 and the third branch circuit with the bridging gap 38. These gaps are set to spark over when the voltage of the condensers reaches a desired value. The effect of the sparkover is to connect the condensers in series through the impedance element 33. The impedance of this element, like that of element 13 in Fig. 1, is comparatively low as compared with that of each of the elements 22, 25, 28, 29 and 32. Under the circumstances, therefore, when the series circuit is closed a very high voltage is developed across the ter` minals 39 and 40 of the element 33, which approximates the sum of the voltages of the condensers 23, 30 and 34.

It will be understood that while the elements 2, 5, 6, 9 and 10 are legged off from the series circuit through the element 13, the leakage through such elements is substantially negligible because the impedance which they offer to the voltage of the series circuit is suiiiciently high to render it so. The same remarks apply Wth respect to the elements 22, 25, 28, 29, 32 and 42 in Fig. 2.

In Fig. 2, I have indicated in dotted lines how the impulse potential may be increased by adding another condenser 41 in still another branch circuit similar to either one of the other branch circuits in the same figure. The new branch comprises in series with the condenser 41 a high impedance non-inductive element 42 and a low impedance non inductive element 43 across the terminals of which the impulse voltage is developed. This new branch circuit is shunted by a spark gap 44 similar to the spark gap 38. Vhen the new branch is added the impedance of the ele- I ment 33 is increased to correspond with that of either of the elements 25 or 29. When this is done, the terminal elements 39 and 40 are omitted.

Therefore, in Fig.2 I have indicated how three or four, or any other number of condensers may be employed in the generator. If it is desired to increase the voltage of the impulse generator, another branch circuit may be added similar to the one indicated in dotted lines and again the impedance of element 43 will be increased just as the .impedance of the element 33 was increased when the new branch was added. In the same Way, branch circuits may be added in Fig. 1. If it were desirable to limit the impulse generator to two condensers, the thirdbranch circuit including the impedance elements 10 and 13 could be omitted and the impedance element 9 reduced to correspond with that of the element 13.

Therefore, in the improved generator, .the condensers are charged directly from a source of alternatingcurrent to the voltage desired, whereupon at that instant, the charging operation is cut off by the spark-over of the limiting gaps. The same operation places the charged condensers in series with an impedance element of'proper value, thus setting the generator in operation and producing across the termin als ofthe impedance element whatever voltage is desired. Furthermore, the characteristic o f the impulse discharge may be readily controlled by varying the elements in the series circuit such as vthe inductance, the capacitance, or the resistance.

It will be clear from the foregoing that the spark gaps have the following functions: first, to determine the voltage of the generator impulse; second, to eliminate the high impedance elements from the discharge circuit; and third, to initiate the impulse discharge.

It will be understood that while I have disclosed my invention in connection .with specitic. circuits and apparatus, I do not wish to be so limitedinasmuch as I contemplate variations and modifications which do not depart from the spirit of the invention or from the scope of the claims contained herein. For example, under certain conditions it may be desirable -to insert on. either or both sides of the spark gap 36 a high resistance non-inductive element, each element being shunted by a small spark gap as compared with the spark gaps 36, 37 and 38 in order to prevent the spark gap 36 from sparking overprematurely, as for example, when corona discharges take place along the line. leading from the terminal 26 of the transformer B. I also contemplate substituting for the non-inductive resistance elements in the branch circuits any other suitable form of impedance, as well as modifying the circuit of Fig. 1 by omitting the element 2 and connecting the condenser 3 directly to the conductors 14.

What I claim as new anddesire to secure by Letters Patent ofthe United States, is:

1. In a discharge device, a source of alternating current, a plurality of condensers, each in a s eparatebranch circuit, each branch circuit containing in series with the condenser, an

impedance, said branches being connected each in series with saidsource whereby said condensers may be chargedin multiple, and means for connecting all of said condensers in series with an impedance, all of said impedances save the last one mentioned, and said source of alternating current, being located outside `of said series circuit whereby said n condensers may be discharged in series for producing an 'impulseV discharge between the terminals of said impedance in said series circuit. Y

2. In a discharge device, a source f alternating current, a plurality of condensers each in an individual branch circuit in'series with an impedance element on each side thereof, said branches being connected each in series with said source whereby saidcondensers may be charged in multiple, and means for connecting said condensers in a series circuit with one of said impedances, all of the other impedances and the .said source being located outside of said series circuit, said :meanscom-I prising a spark gas between veach condenser andthe next one to it in the seriesl circuit, said gaps being set'whereby" when the charging voltages reach a given value the gaps will spark over and closethe said series circuit to f therethrough and create a potential across the terminals of the impedance inthe series circuit and whereby an impulse discharge may be obtained from said terminals, the impedance in the series circuit being comparativel low-in value as regards the series circuit discharge and all the other impedances being comparatively high in value as regards the series circuit discharge. y

3. Ina discharge device, a source of alternating current, a plurality of condensers each located in an individual branch circuit in series with a high impedance, said branch circuits being each connected in series with said source whereby said condensers may be charged in multiple, and means for connecting said condensers in a series circuit, all of sald impedances and said alternating current source being located outside the'series circuit, a non-inductive low impedance being in series with said condensers in said series circuit,

Nnating current, a plurality of condensers each located in an individual branch circuit in series with a high impedance, said branch circuits being connected each in series with said source, and means 'for connecting 'said condensers in a series circuit, all of'said impedances and ysaid alternating current source being located outside the series circuit, a non-inductive low impedance in series with said condensers in said vseries circuit, said means consisting of spark gaps between each condenser and the next one to it in the series circuit, 'said gaps being set whereby when the charging voltage reacnesa given value the gaps will spark over and close the. series circuit where- -by a potential is produced at the terminals of located across the two points common to all of the charging circuit of the condenser whereby the source of supply is short-circuited with respect to the condensers When the sparkover takes place. y f

5. In a discharge device, a source'of alternating current, a plurality of condensers each in -an individual branch circuit in series with a high impedance, all of said circuits being connected in 'multiple across the said current source whereby they may be charged in multiple, means for connecting said condensers in a series circuit, said current Source and said impedance being located outside of the series circuit, and an impedance in said series circuit `and in series with -saidv condensers whereby a discharge takes place through said impedance in the series circuit and a potential is created across its terminals for producing an impulse discharge.

vIn Witness whereof, I have hereunto set my hand this 24th day of December, 1928.

FRANK W. PEEK, JR.

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