US1349907A - Apparatus for rectifying electric currents - Google Patents

Description

A. F. NESBIT. APPARATUS FOR RECTIFYING ELECTRIC CURRENTS.

' APPLICATION FILED AUG-20 19F. 1,349,907, Patented Aug. 17, 1920.

2 SHEEg-SHEET l.

1% A9 5 a I Smvmto'e A. F. NESBIT. APHRMus FOR RECTIFYING ELECTRIC CURRENTS.

I u APPLICAUDN FILED AUG.20,19H. 1,349,907. Patented Aug. 17,1920.

2 SHEEN-SHEET 2 PATENT OFFICE.

ARTHUR F. NESBIT, OF WILKINSBURG, PENNSYLVANIA.

APPARATUS FOR RECTIFYING ELECTRIC CURRENTS.

Specification of Letters Patent.

Patented Aug. 1'7, 1920.

Application filed August 20, 1914. Serial No. 857,796.

To all whom it may concern:

Be it known that I, An'rnvu F. Nnsisrr, a citizen of the United States, residing at Wllkinsburg, in the county of Alleghen and State of Pennsylvania, have inventet new and useful Improvements in Apparatus for Rectifying Electric Currents, of which the following is a specification.

This invention relates to the rectifying of alternating, oscillating, or pulsating electric currents.

()ne object of the invention is to provide improved means whereby alternating electric currents are rectified, so as to be made non-intermittent and wholly unidirectional.

Another object of the invention is the provision of electrical apparatus having the novel combinations and arrangement of parts, shown in the drawings, to be fully set forth hereinafter, and to be particularly pointed out in the appended claims.

In the accompanying drawings, Figures 1, 2, and 3 are diagrams illustrating the theory of my invention.

Fig. 4 is a diagram showing one arrange ment of apparatus embodying my invention.

Fig. 5 is a diagram showing a modified arrangement of apparatus, constructed in accordance with my invention.

Fig. 6 is a diagram showing a further modification in the construction and arrangem'ent of apparatus embodying the invention.

Fig. 7 is a diagram illustrating electromotive force waves before rectification.

Figs. 8, 9, and 10, are diagrams illustrating electromotive force waves of varying maximum values after rectification, in accordance with my invention.

Figs. 11, 12, 13, 14, and 15, are diagrams illustrating other applications of my invention in producing non-intermittent, unidirectional currents.

In Fig. 1 of the drawings, the electrically neutral condition existing in the gas between the point A and the disk D, before the electric field is established, is disturbed by this field, and ionization by collision is set up, feeble though it may be. As the voltage between the electrodes A and D is increased, a. faint hissing or snapping sound is heard, which sound becomes more and more audible. When the sparking value of the voltage difference has been reached, a sharp noisy or snapping spark passes between the electrodes, said spark being to all appearance,

a fine line, more or less irregular in its path, depending upon its length and the suspended particles in the space through which it takes place. As the voltage is further increased, this spark becomes more continuous and finally passes into an arc.

In Fig. 2, a sharp pointedconductor A and a fiat disk D are made the electrodes of a spark gap and joined in a circuit with a source of alternating electromotive force. It is not necessary that the pointed electrode should be placed opposite the center of the disk for the reason that the spark gap operates equally well when the electrode A is directed toward a point on the disk not near the edge of the latter. A spark gap of this type will be hereinafter called an asymmetrical spark gap. In the circuit between the points 10 and 11, is inserted a water voltameter 12. As the voltage impressed upon the primary coil 13 is increased, the potential across the terminals of the secondary coil 14 is raised in accordance with the well known laws governed by the transformation ratio of the transformer. 'When the secondary voltage has been raised high enough to give rise to a spark between the point A and the disk D, a sudden liberation of gases takes place in the two arms of the voltameter, said gases being indicated by the letters H and 0, respectively. Still further elevating the secondary voltage causes the sparks to become more and more frequent and noisy, and finally a stage is reached when an arc is formed. For the voltage at which this are is formed, the arc is found to be more or less luminous in appearance and rather unstable in the position it occupies on the disk. Upon lowering the voltage, a stage is reached when the are hecomes very steady and comparatively quiet, except for the humming which is always characteristic of the alternating are. For a spark gap one and one half inches between the electrodes, the arc stream is ap roximately conical in sha e, with a base 0 from one to one and a hal inches in diameter on thedisk. The fine pointed electrode gradually assumes a mushroom tip which appears as a bright spot of light or scintillating star. The center of the arc stream base, on the disk, appears as a bright s ot not so luminous as the tip of the pointer electrode. The gases liberated in the water voltameter are very ap roximately of volume ratio two to one, an when tested give the usual evident that they are hydrogen and oxygen, respectively. From the foregoing experiment with the circuit of Fig. 2, it is seen that the selection of two electrodes, such as A and D' has brought about the condition that the flow of ions from the pointed electrode toward the flat disk greatly exceeds the simultaneous flow of ions from the disk toward the int.

If the spark gap electrodes of Fig. 2 are interchanged, as illustrated in Fig. 3, the liberated hydrogen and oxygen are found to be collected in the limbs of the water voltameter, the o posite to that of Fi 2. For an equal lengtli of test or run, equa relative amounts of hydrogen and oxygen are liberated for the circuits of Fi 2 and 3. Thus the use of a spark gap wit a pair of asymmetrical electrodes, such as a fine pointed conductor and a flat disk, acts as a sort of check valve against the flow of current across the gap from the disk toward the pointed electrode.

In Fig. 7 I have illustrated the curves of an alternating electromotive force Wave of a given frequency. The ordinate E, may be considered to represent either the mai zimum value of the alternating current electromotive force wave, which value is just suflicient to produce a spark across the gap from the pointed electrode to the disk, or it may represent the maximum value of the alternating current electromotive force wave, an application ofwhich to the gap is just sufficient to maintain an arc. For' a spark gap of given length, the longer the period of time t during which the ordinate of the electromotive force wave is above the value of E the longer will be the interval during which the arc will be maintained between the pointed electrode and the disk, and this is independent of the persistence of the arc stream to maintain the arc until the voltage has a ain risen to a value approximating E During the second half of the first cycle of the electromotive force wave only a feeble current, if any at all, can flow across the gap from the disk D to the pointed electrode A. During the third half Wave of the electromotive force there is a repetition of the phenomena outlined for the first half wave. -It is thus seen that the conditions are at least sutlicient for the maintenance of an are between the ointed electrode and the disk during all t e odd numbered half waves of the electromotive force. When the frequency of the impressed electromotive force wave is not low enough to allow an appreciable contraction and cooling of the arc stream during the suppressed wave intervals, e. the even numbered half waves, the arc stream is subjected to the same tendency to be extinguished, as is commonly um erstood to hold with low current alternating arcs, especially when the current wave passes throu h its zero value. When the time elapsing etween the first and third half Wave is so small that the cooling of the ionic streams does not extinguish the arc, the latter persists as far as the e e can determine. With a circuit such as i lustrated in Fig. 2, the current flows from the pointed electrode toward the disk, during the intervals l, 3, 5, etc., of Fig. 8, and

there is a suppression of the current during the intervals 2, 4, etc.

If a middle tap 15 of the transformer secondary 14 is brought out and connected through a voltameter 12, then through the adjustable inductances L, L to the disks D D as in Fig. 4; or if two transformers have their second series 14 and 14' joined in series as in Fig. 5, and the lead 15 is connected with the voltameter at a point between said coils, then both the odd and even numered half waves are utilized, it being understood that one terminal of the secondary is connected with a pointed electrode A and the other terminal with a pointed electrode B, said electrodes being on opposite sides of the disks D, D These inductance coils L, L tend to smooth out the fluctions in the current wave resulting from the superimposed electromotive forces. Thus in Fig. 5 during the positive half of the one cycle or interval 1, of the electromotive force wave (see Fig. 9), the current flows from 14 to A, thence across the air gap to the adjacent side of the disk D, thence through the water voltameter to the terminal 15, no current passin from the disk D to the electrode B. During the second interval, or negative half of the first cycle of the electromotive force wave, the current reverses in direction in the secondaries 14, 145', and consequently flows from 14 toward B, thence to the disk D (none passing to A), thence through the water voltameter to the terminal 15. With a circuit, as in Fig. 5, we now have the utilization of the successive intervals of the electromotive force wave 1, 2, 3, 4, etc., as shown in Fig. 9, toward sending current in the same direction through the water voltameter.

Referring to Fig. 10, if m and y, respectively, represent the relative phase positions of the electromotive force waves and the resultant current waves across the spark gaps from the pointed electrodes toward the disk, the current flow is seen to be intermittent. The current flow may, however, be made unidirectional but non-intermittent, though not of steady value, by the use of a circuit employing condensers, as illustrated in Fig. 6. lnductances may also be employed for this purpose, as is done in the mercury vapor rectifier. Referring to Fig. 6, 13 is the primary coil and 14 the secondary coil the terminals of the latter being connected to pointed electrodes A, B, respectively, condensers 17 and 18 being interposed between the conductors leading to said electrodes. A tap 16 leads from a point between the condensers, said tap having branches providcd with inductances L and L leading to disks D and D The operation is as followsa-Upon the falling olf portion of the first half wave #1, the condenser 17 discharges back into the circuit, the greater part of the discharge taking place across the gap A--D, thus tending to maintain or uphold the current through the are at A--D', even though the i value of the voltage may have fallen below E These condensers 17, 18, are unable to discharge in the directions D"--A', and

-B, hence the phase positions of their discharge currents. are very approximately as shown in dotted lines at a, Fig. 10. In other words the condensers 17 and 18 do not discharge while the E. M. F. of winding 14 is suflicient to charge the condensers. As soon as the E. M. F. of winding 14 falls below the charged E. M. F. of these condensers they begin to discharge from the points to the disks. Thus when the electromotive force impressed by .the transformer or transformers on the gap A'--D' falls-to a value no longer sufficient to maintain the are against its counter electromotive force and the electromotive force of the load between D and 16, the condenser discharge current serves to maintain the arc across the ga until the half wave of electromotive force #2 of the supply has built up to such a value as is sufiicient to start the are between 13' and D. This operation insures that the load current shall at no time become zero in value. I

The type of rectifier herein described may be operated in gaseous orv fluid media within which silent or are discharges may be maintained, and in connection with circuits the frequencies of which may be fixed or adjustcd to high or low values, depending upon the character of the work to be done, or the desire to eliminate the element of personal danger due to the handling of high voltages. Furthermore, the said rectifier may be considered to be theequivalent of a condenser, one plate or metallic conductor of which may assume various shapes and sizes which are relatively of large superficial area compared with the second metallic conductor, which is of small dimensions and which may also assume a great variety of forms, in'so far as the asymmetry of the two conductors is always maintained. Such an asymmetrical condenser (or spark-gap) can receive a charge in the directions A'D, of B'-D in Fig. 5, but cannot return it in the opposite directions respectively.

The relative shapes of the electrodes will be varied to suit conditions, such as current 'arcs against air currents, and at the same volume, shieldilw against air currents, magnetic fields, etc. 11 any instance, a greater or less liberation of hydrogen and oxygen in the water voltameter will be noticeable when there is an appreciable difference in the sizes of the two electrodes for a given length of spark gap. The various forms of concave and convex disks have more or less advantage in their use from the tendency to shelter the time tend to eliminate traveling of the are over the surface of this same electrode. When sheltering of the arc is necessary, or it is to take place in a gaseous or fluid media, it may be completely inclosed by a casing which may be more or less air tight and at the same time of opaque or transparent material. It may be necessary in some cases, to protect the are against deflection due to magnetic fields. In such instances a magnetic screen or shield may be employed. The electrodes may be' made ofmetallic or non- -metallic material, according to the medium through which the discharge takes place. The medium may contain gases in the preseneeaof water or other vapors, and the chemical action of. thedischarge may'produce acid reactions which would tend to destroy the electrodes. It is obvious that a plurality'of arcs ma be employed in parallel with each'other an independently operated when thecurrent required exceeds that permissible with a single spark ap.

Unidirectional currents 0 the type obtained by the spark gap herein described have a wide application in the arts. Fig. 11, for instance, illustrates possible circuit connections for the employment of the invention in connection with the operation of X-ray tubes. The arrangement of the spark gap circuit is the same as in Fig. 6. The alternating current supply system 25 is provided with the usual rheos'tat 26 and controlling switch 27, and the terminals of the secondary coil 14 are connected with the pointed electrodes A, B. Said electrodes are also respectively connected with the condensers 17 and 18. One terminal 28 of the X-ray aparatus 29 is connected with the disks D,

2 through inductances L, L, and the other 11:, terminal of said apparatus is connected by means of a conductor 30 (with the condensers 17, 18. The operation will be readily understood fromthe description of the previous figures.

Fig. 12 illustrates one form of circuit eon-. neetions which may be employed in wireless telegraphy. In this figure, the current supply is provided with a key 31, and the primary coil 32 of a transformer is substituted for the X-ray apparatus of Fig. 12. The secondary coi 33 is connected with the usual spark gap 34, condensers 35, and coil 36 cooperating with antenna 37.

This type of spark gap placed as a shunt to a condenser 38, Fig. 13, will discharge readily through the path a, A, l), 03, and hence feebly across the gap 39 in the direction ef. 'VVhen tending to discharge around the circuit in the opposite direction d, l), A, a, the valve action more or less throttles the flow along this path and simultaneously causes a copious discharge across gap 39 in the direction f c. This igap thus becomes the seat of unidirectional oscillations, the magnitude and character of which are do )endent upon the adj ustment of :the gap A- as well as upon the constants of the circuit containing the condensers 35 and the coil 36.

Fi 14 and 15 illustrate two additional possi le groupings of these spark gaps in order to produce electrical oscillations of unidirectional character. F ig. 14 difi'ers from Fig. 11 principally in providin a spark ap 40 interposed between the eectrodes l), D, and the conductor connecting the condensers 17-, 18. In Fig. 15 the two electrodes A',-B', respectively, are connected with a condenser 41. The disk D is cannected with one end'of a circuit comprising wire 42, condenser 43, coil 44, condenser 45, and wire 46, the terminals of wires 42 and 46 are brid ed by a spark gap 47. The wire 46 is provided with oppositely disposed terminals A spaced from disks D to form )ark gaps, said disks being connected with The wires lead from the coil 14 at points between the con enser 41 and electrodes A, B DI.

The electrical precipitation vof suspended matter in gaseous and fluid bodies may also be effectively accomplished by means of high voltage unidirectional corona dischar es. Further application may be made to wireless telephone; to electrolysis; charging of stora e cells; to endosmotic phenomena especia ly manifest when badly conducting fluids are used; to the production of chemical actions in gaseous and fluid bodies, such as the fixation of nitrogen and the production of ozone, etc, by the action of electrical discharges; to the formation of endothermic compounds under the influence of the silent dischar'gHinde there is no appreciable elevation of temperature in their reactions; to bringing about simple organic synthesis similar to those which pla'nts eilect under the action of sunlight; a fixed portion of the current from an alternating current generator may be rectified and used for the purpose of providing a means of partial or igeaepov complete self-excitation; the transmission of power 'by unidirectional currents, etc. :In this connection, it will be understood that I do not desire to limit myself to the exact form and materials for the asymmetrical spark gap materials as specified in the fore,- going detail description, nor to the few special applications of such a spark gap as have been herein enumerated.

Ha'ving thus explained the nature of my invention and described an operative mannor of constructing and using the same, although without attempting to set forth all of the forms in which it may be made, or all oftlie forms of its use, what 1 claim is 1. The combination with an electrical apparatus fo'r receivin unidirectional currents, of regulating evices, disks conn'ected through said regulating devices to one terminal of said apparatus, electrodes placed upon pposite sides of and spaced from said disks to form spa'r'k gaps, and means connected with 'saideledtrodes for supplying alternating; oscillating or pulsating currents. y

'2. The combination with ah electrical apparatlus for *Ieceiying unidirectional 'cur rents. of regulating devices, disks connected through said regulating devices to one terminal of said apparatus, electrodes placed upon opposite sides of and spaced from said disks to form spark gaps, means for supplying altematin'g, oscillating or pulsating currents to sai electrodes, and means for maintaining the arcs at the spark gaps during the suppressed portions of the electromotive force waves.

3. The cdmbination with an electrical apparatus for receiving unidirectional currents of regulating device's, disks connected through said regulating devices to one terminal of said apparatus, electrodes placed on o posite sides ti and spaced from said disks tofo'rm sparkgaps, condensers connected with said electrodes and with the other terminal of said electrical apparatus, nu means for supplying alternating oscilating "or pulsating currents 'to said electrodes.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

ARTHUR F. NESBIT.

Withesses DAYTON ULRnY, W. J; Moonn.

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