US1963160A - Control of inverse voltage - Google Patents

Control of inverse voltage Download PDF

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Publication number
US1963160A
US1963160A US314030A US31403028A US1963160A US 1963160 A US1963160 A US 1963160A US 314030 A US314030 A US 314030A US 31403028 A US31403028 A US 31403028A US 1963160 A US1963160 A US 1963160A
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Prior art keywords
transformer
wave
circuit
tube
ray
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Expired - Lifetime
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US314030A
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English (en)
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Julius B Wantz
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General Electric X Ray Corp
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General Electric X Ray Corp
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Priority to US314030A priority Critical patent/US1963160A/en
Priority to FR682923D priority patent/FR682923A/fr
Priority to DEV25855D priority patent/DE538384C/de
Priority to GB31588/29A priority patent/GB342263A/en
Priority to BE364688A priority patent/BE364688A/fr
Application granted granted Critical
Publication of US1963160A publication Critical patent/US1963160A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/10—Power supply arrangements for feeding the X-ray tube
    • H05G1/14—Power supply arrangements for feeding the X-ray tube with single-phase low-frequency AC also when a rectifier element is in series with the X-ray tube
    • H05G1/16—Reducing the peak-inverse voltage

Definitions

  • the energy consuming device embodies in itself the necessary rectfying function. That is, the device itself is a valve permitting the flow therethrough of elec- 20, trical pulsations, generally referred to as the useful half of the Wave, and rejecting the alternate pulsations, which amounts in such an instance to the undesired or unused portion of the wave.
  • This tube because of the design of its electrodes and also because of the high vacuum existing Withinthe en- 3@ 'velope thereof, will only permit ⁇ the passage of'current through it in one direction, on the one hand, passing the useful alternation of the current wave of the selected polarity and rejecting the remaining half Wave thereof, so that a tube v is energized by, a pulsating unidirectional current comprising only the alternations of selected polarity.
  • the rejected half cycle is generally termed in-l verse, and it performs with an X-ray tubeno use- 40 ful function, but is a distinct detriment to the operation. of a tube, and provides a factor in problems of insulation which must be fully considered in the design of X-ray apparatus intended to be used with such a self -rectifying X-ray tube.
  • any X-ray apparatus of the oil-immersed type just as is the case in any other X-ray apparatus', or in any other electrical device using high tension electricity, resides in the ability of the engineer designing such apparatus to take care of the problem of insulation. This is an immense factor in present day X-ray apparatus, especially that' of the oil-immersed type.
  • self-rectifying tubes are employed in tanks of limited capacity, the tanks containing transformer oil for the purpose of insulation.
  • the' potential of the useful portion of the vvaveV is less than that of the unused portion'. This is due to the fact that the useful portion of the' Wave being utilized in the X-ray tube i-ts potential is diminished by an amount equal to the voltage drop ⁇ in the source of energy which is de'- pendent on the amount of current passing through the X-ray tube. As no current' passes When the inverse half cycle is impressed across the tube this voltage loss is not present and the' full potential generated by the source of current is impressed on the X-ray tube. On an oscillo- 10 graph diagram made for determining this question, invariably it is shown that the amplitude of the useful portion of the wave is from ten to twenty percent less than the amplitude of the inverse portion of the Wave.
  • Insulation must be provided to take care of the highest potential present in the apparatus and as the potential of the inverse half wave is from ten to twenty per cent greater than that of the useful part of the Wave it is necessary that the X-ray engineer insulate for a potential of greater magnitude than that which is usefully employed in generating X-rays.
  • the present day oil-immersed X-ray apparatus is provided with insulation adapted to take care of a greater voltage than that which is actually used in theX- ray tube contained in the apparatus.
  • This invention is designed for the express purpose of increasing the useful load which may be impressed upon an electrical device of given design and to increase the capacity of presentl day apparatus for a useful load to the limit of the insulation therein, such insulation now, as previously stated, being in excess of that required to withstand the highest potential used by the device.
  • This result may be accomplished by reducing ythe potential of the inverse half cycle until it is of an amplitude not greater than the amplitude of the used half cycle.
  • the invention need stop with equalizlng the inverse and the used portion of the Wave, but that it will extend to a complete control of the inverse whereby it may be regulated so that its potential is in a selected or desired quantity, approaching zero as a limit.
  • the present invention is applicable to a large number of problems of electrical insulation for apparatus, and is in no way conned exclusively to the X-ray art, but is capable of adoption to any type of apparatus re quiring unilateral current and which is energized directly from a source of alternating current.
  • the objects of the invention include- Means providing for an increase in the operating potential of vacuum tubes and other electricallapparatus which rectify their own current, as well as means for reducing the magnitude of the unused portion ofthe electromotive force used for energizing such tubes or apparatus.
  • a circuit incorporating an energy consuming device operate-d on a selected portion of an electrical impulse and in association with a device in which insulation must be provided in excess of that required for the used portion of the impulse to prevent breakdown of the insulation through the strain produced by such unused portion thereof whereby such strain produced by such unused portion is reduced to permit of the energy of the useful impulse to be correspondingly increased.
  • the object of the invention includes means for controlling such reduction, and means for synchronizing the reducing means with the apparatus using the useful portion of the Wave so that there will be a coordination of loads upon the apparatus one using the useful portion of the wave and another the inverse portion thereof so that the latter may function in an increasing quantity when the load upon the apparatus energized by the useful portion of the Wave is increased.
  • Another important object of the invention is to provide a relatively simple apparatus which will perform the objects hereinabove identified.
  • Figure 1 is a schematic diagram showing the energizing circuit for an X-ray tube of atype capable of rectifying its own current.
  • Figure 2 is a set of curves showing the voltage impressed across the terminals of an X-ray tube when energized in a circuit such as is shown in Figure 1.
  • Figure 3 is a set of vcurves showing the voltage across and current through the primary of a high tension transformer such as is shown in Figure l when in an X-ray tube circuit.
  • Figure 4 is a schematic diagram showing a new and improved circuit for energizing an X-ray' tube of the type capable of rectifying its own current and in which a separate absorption circuit has been included for the purpose of increasing the X-ray output from such a tube.
  • Figure 5 is a curve showing the voltage impressed across the terminals of an X-ray tube when energized in a circuit such as is shown in Figure 4.
  • Figure 6 is a set of curves showing the Voltage across and the current through the primary of 1% a high tension transformer such as is shown in Figure 4 when in an X-ray tube circuit.
  • Figure 7 is a schematicdiagram of a device constructed in accordance with the invention and in which the selective portion of the absorption circuit consists of a mechanical rectifier driven by a synchronous motor.
  • Figure 8 is a device similar to that illustrated in Figure 7, but in which the synchronous rectier is replaced by a thermionic vacuum tube.
  • Another device by which the same result may be obtained is the paralleling of the useful load with an absorbing circuit, both operating from the same secondary.
  • the present invention has to do with a medium for increasing the useful results obtainable from an electrical device of a given size which is energized from high tension transformer direct and which recties its own current, and it has also to do with any device which is adapted to be energized by half the wave, and in which it is desirable tocontrol the inverse potential.
  • FIG. 1 the ordinary circuit used in X-ray work is shown schematically.
  • an X-ray tube 20 which is provided with an anode 21 and a cathode 22.
  • the X-ray tube is of the heated type, generally designated in the art as a Coolidge tube, and the cathode 22 thereof is provided with a heated filament which is energized through the medium of a transformer 23.
  • the transformer A23 is normally of the step down variety and the secondary 24 thereof, which is connected to cathode 22, is insulated from the primary 25 thereof by suicient insulation to withstand approximately one-half of the voltage across the terminals of the tube 20.
  • One connection between the cathode 22 and the secondary 24 is connected to one terminal of the secondary 27 of, a high tension transformer 26 which is employed for furnishing the high potential alternating current necessary to energize the X-ray tube 20.
  • the other terminal of the secondary 27 is connected in the usual manner to the anode 21 of the tube 20.
  • the primary 28 of the high tension transformer is energized in any suitable manner, for instance,
  • Variation in the heating of the filament 22 is obtainable through the ⁇ medium of any regulatory device connected within either the prima-ry or the Ysecondary circuit of the filament transformer 23.
  • this part ofthe device comprises a variable resistance 32 in series with the primary 25 of the lament transformer 23 which transformer in turn is energized from a source of energy 30.
  • the alternation shown at 37 illustratesthe useful current Wave or that4 portion of the cycle of correct polarity for energizing the tubewhich 125 is accepted by the tube and which passes through such tube for the generation of X-rays.
  • No rea'- son is apparent for discussing the operation of va self-rectifying tube in great detail for it is well known how an X-ray tube selects the alternation 130 of proper polarity. This subject has formed the subject matter of a number of patent applications and is common knowledge in the art.
  • Alternation 38 shown inrdotted lines in Figure 2, represents alternation 37 projected against 135 alternation 36, and shows the comparative differences in height, amplitude, or area ofthe useful voltage and the inverse voltage wave.
  • the numeral 39 is used to indicate the diiference in height between the peak of the useful 140 and of the rejected wave. Under normal conditions, the height of these alternations are to each other approximately as is to 100. In other words, it is necessary to provide insulation inthe v high tension transformer 26 for 1,00 kilovolts for 145 every 85 kilovolts used in the X-ray tube 20.
  • the tube 20 must be designed in such proportions as to withstand Vthe potential vof kilovolts for everya e5 kilovolts used in energizing Such tube.
  • one of the provisions of the present invention is to make it unnecessary to add insulation to transformers Vfor a voltage higher than that used for a useful load.
  • FIG. 4l there is a circuit analogous to that shown in Figure 1. Similar reference characters are applied thereto, and the description of the circuit shown in Figure l can be read directly upon Figure 4.V In addition, however, there is a ⁇ selective loading circuit associated therewith and in direct connection with the high tension transformer- 26.
  • a second secondary 33 herein sometimes referred to as an auxiliary secondary although lprobably not in a true sense an auxiliary of the main secondary of said transformer, associated with a selective-loading device indicated at 34.
  • This latter device may be of any selective variety. Its function is to absorb sufficient energy during the alternation through which the X-ray tube is will permit current to pass to the loading device 34 during the alternation not used by the X-ray tube.
  • the selector may take the form of asynchronous mechanical switch, a thermi'onic device, a vibrating polarized relay, a cold cathode rectifier, a mercury arc rectifier, a chemical rectifier, an electrostatic rectifier, or any of the devices having unilateral conductivity ⁇ well known in the art. It is to be conceived that additional and better devices possessing unilateral conductivity will later be introduced and such devices, as they are developed may be substituted for any of the above named, or for any one of such devices which has been omitted from the foregoing list.
  • the relative height of these halves of waves may be altered so that, if necessary, the unused portion of the wave may be reduced to a lower value than the used portion of the wave, or vice versa. It is apparent, at once, that by the system graphically illustrated in Figure 4, and hereinafter to be more completely described, that there is complete mastery of the unused portion of the wave and that it may be controlled at the will of the operator to be equal to, less than or greater than the height or amplitude of the useful portion of the wave, as is necessary, advantageous, or desired.
  • Figure 3 represents the voltage wave across the primary of the high tension transformer 26, the unused alternation being designated 41 and the useful portion or alternation being designated 42.
  • Y v represents the voltage wave across the primary of the high tension transformer 26, the unused alternation being designated 41 and the useful portion or alternation being designated 42.
  • the voltage wave is represented by the reference character 55, the unused portion being designated 56, and the alternation which is used by -the character 57.
  • the current through the primary of the transformer of Figure 4 is designated by the curve 60, the curve 6l shows the unused portion of the wave, and the curve 62 the useful portion.
  • An examination of these wave shapes discloses a marked improvement in the power factor by the use of an absorbing circuit as may be readily worked out byv a comparison of Figure 3 with Figure 6. 7
  • a device such as is shown in Figure l1 has a power factor of approximately 47%.
  • the same device with the absorbing circuit included therein shows a power factor of approximately 90%.
  • the phase shift on ⁇ the used portion of the Wave will be seen to be approximately identical in both Figures 3 and 6, the change in the power factor taking place ⁇ in the unused portion of the wave.
  • an X-ray tube designated 67 the parts thereof are easily recognized.
  • the anode is designated 68, and the cathode 69.
  • a lainent Within the -tube and mounted in the usual manner is a lainent, which is energized by a filament transformer 70, they filament Within the X-ray tube being energized by the secondary 71 of such lament transformer.
  • the primary of such filament transformer is designated 72.
  • a high tension transformer 73 such transformer having a secondary 74 used to energize the tube 67, and an auxiliary secondary designated 75 which forms a part of the absorption circuit, each of which secondaries is energized by a single primary 76 in such transformer 73.
  • a milliammeter 77 There is disposed in the high, tension tube energizing circuit a milliammeter 77.
  • one leg of thecircuit leading to the high tension primary 76 there is an auto transformer 78 possessing a plurality of taps 79 each of which is provided with a contact kbutton 80.
  • the other leg of the circuit is from one transformer directly to the other.
  • -In the auto-transformer 78 is a ring 81 connected to one sideof the transformer primary 76,Y and associated with said ring 81 is a contact lever 82 which-is ladapted to swing upon a pivot 83.
  • a plungercontact 84 which is insulated from lcontact lever 82 is employed for making contact with ring 81.
  • a second plunger Contact 85 is insulated from contact lever 82 and is for making contact one at a time with the contact points 80. Between the plunger contacts 84 and 85 is a conductoror connector 86.
  • a main switch 87 Associated with the circuit from the source of power to the auto-transformer 78 is a main switch 87 by which the impression of energy upon the auto-transformer from a source of alternating current 88 is controlled.
  • an operating switch 89 for energizing the autotransformer 78 there -being in such a switch a button 90 employed to establish a connection with auto-transformer 78 through a resistance 91.
  • a plunger contact 96 ⁇ making contact with buttons 94, and in juxtaposition thereto is asecond plunger contact 97 contacting with the ring 95. Between the plunger contact 96 and the plunger contact 97 there is a conductor or connector 98.
  • the selective portion of the absorption circuit is designated 99, and a second absorption resistance in the absorption circuit is marked 100.
  • a contact lever 103 which is mounted upon pivot 104, there being on the lever 103 contact plunger 105 which is adapted to engage the points 101 one at a time and a second contact plunger 106 which engages the rail 102.
  • a connector or conductor 107 is intermediate the plungers 105 and 106.
  • resistance 108 In association with the filament transformer primary 72, there is a resistance 108 in series therewith for the purpose of regulating the potential across the primary 72 of theY filament transformer and conjointly controlling the heating of the filament in cathode 69.
  • the resistancesl 108 are so arranged that they are controlled by the same handle as is used for resistances 100.
  • contact points 10'9v in circuit with resistances 108, and associated'- at a time is designated 111 and a plunger Contactv engaging the rail 110 is marked 112, the connection between plunger contacts 111 and 112 being ⁇ with the device is a Contact rail 110 connected to one side ofthe line from-the source ⁇ ofpowerj A plunger Contact ⁇ engaging points 109 one the selection of the alternation to be loaded.
  • the mechanical selector there is a contact brush 115 electrically connected to rail-95,.
  • a commutator 117 is driven byva four pole the lines connected to thepower source 8,8 and which operates at 1800 revolutions per minute at 60 cycles, or at 75 revolutionsper minute at 25 .ments 120 is marked 121.
  • commutator segments aredesigy 14o synchronous motor 118 which is energized from in Figure 7, with each cycle of alternating current from the sourceof power 88 passing through the auto-transformer 78, there is induced from the primary 76 of transformer 73 a separate current Wave in each of the secondaries 75 and 74.
  • the useful portion of the current induced in the secondary 74 is adapted to energize the X-ray tube 67.
  • the inverse potential should be depressed or suppressed to such an extent that the peak attained thereby will not exceed the peak of the used portion of the Wave. It should suggest itself then that the resistance in the absorption circuit will have to be varied 'according to the load upon the secondary 74.
  • the amount or resistance required for any given load may readily be calculated, so that in the auto-transformer 78, .there is supplied in association with resistance 93 buttons 94 which correspond with and are complemental to the buttons upon the taps 79 in the auto-transformer, so that when any particular adjustment of the auto-transformer 78 is made, there Will be a corresponding increase or decrease in the amount of resistance in the absorber circuit.
  • the amount of resistance in such absorber circuit will therefore, at all times, be sufcient to suppress the inverse to the extent that the peak of the inverse potential Wave is never greater than the peak of the used portion of the Wave.
  • the hereinabove referred to compensating regulation of the resistance in the absorber circuit relates to and has to do only with the load Which may be controlled through the auto-transformer.
  • the temperature of the filament in an X-ray tube is adapted to control, Within limitations, the amount of energy passed thereacross and consequently the amount of X-light generated therein.
  • the resistance inY the absorber circuit may be balanced toapproximately that point Where there will be a suppression of inverse only to the
  • the inclusion of a load for the unused'portion of the Wave destroys all of the disadvantages which have heretofore been found in providing a transformer with a loadV comprisingl .a device adapted to be energized only by a unilateral current, there then always being surges or fluctuations because of the unloading of the transformer when the alternation changes to that of opposite polarity.
  • a device adapted to be energized by a unilateral flow of current, and which is of such a construction that the alternation of opposite polarity cannot pass therethrough, as for example a kenotron, or the like.
  • a filament current transformer To energize such thermionic device, it is necessary to have a filament current transformer as is well known in the art.
  • the thermionic selector is designated 122, and there is a plate 123 therein electrically connected to the rail ⁇ 102.
  • the i'ilamentary cathode 124 in the selector 122 is electrically connected to rail 95.
  • a transformer 125 for heating purposes, the secondary thereof being desig-l nated 126 and the primary 127. Such primary is energized by conduits or linesconnected to the source of power 88.
  • auxiliary secondary 75 is unused, it being unable to pass through tube 122.
  • the load therefore, upon the primary '76 is made substantially constant by the alternate employment of such load, primarily for a useful purpose, namely, the generation of X-rays in the tube 67 upon one half of the current wave, and upon the other half of the wave, the production of suicient energy that the coil is required to energize the resistances 93 and 100 to that extent that the peak of the inverse and the peak of the used portion of the wave are substantially the same.
  • a useful load to be an X-ray tube. It is not intended that the invention is to be limited to this particular application for it may be ⁇ iust as readily applied to any other device which consumes only every other alternation and in which the potential of the idle alternation rises above that of the useful alternation.
  • the invention is especially applicable to those devices where it is necessary to prevent increase in the size of the container for the high tension transformer and for the tube.
  • such devices in part being illustrated in several cri-pending applications, namely, Serial No. 286.825, led June '2.9. 1928. entitled X-ray operating table.
  • an X-ray tube having a primary and a plurality of secondaries, a circuit including one of said secondaries and said tube, a source of power, a variable impedance, an absorption circuit including said variable impedance and the other of said secondaries, an auto-transformer, a circuit including said auto-transformer, said source of power and said primary, a selector switch for closing said absorption circuit so that it may be energized with the half waves rejected by said X-ray tube, and a unitary control member interlocking said auto-transformer and said variable impedance for conjoint adjustment.
  • a transformer having a primary and two secondaries, a source of alternating current, a circuit intermediate said source of alternating current and said primary, a rheostat in said circuit, an X-ray tube, connections from one of said secondaries to said tube, a second rheostat, an absorption circuit including the second of said secondaries and said second rheostat, the X-ray tube passing one half wave of each alternation from the alternating current source, selector means in circuit with said absorption circuit for closing said circuit to passv the other half wave of said alternating current through said second rheostat, and interlocking control means for conjointly operating said rheostats.
  • An electrical system comprising a circuit having a load of unilateral conductivity therein, an absorption circuit having a variable impedance therein, a source of power, a transformer having a primary in circuit with said source of power and two secondaries, one of said secondaries being in circuit with said load, the other secondary being in said absorption circuit, a rheostat in the circuit to the primary of said transformer, a selector for energizing said absorption circuit with the half waves rejected by said load, and means for interlocking said rheostat and said variable impedance for conjoint predetermined relative adjustments.
  • An X-ray system comprising a source of energy, a transformer having a primary and two secondaries, an X-ray tube, a selector device, an auto-transformer intermediate said source of power and said primary, a circuit including one of said secondaries and said tube, a variable impedance, an absorption circuit having said variable impedance therein and including said second secondary and said selector device, said absorption circuit being closed by said selector to receive half waves not useful for energizing said tube, and an interlock between said auto-trans former and said variable impedance for conjoint predetermined adjustment.
  • An X-ray tube having a filament therein, a source of power, an auto-transformer, a main transformer having a primaryv and two secondaries, .a circuit including said primary, said autotransformer and said source of power, a circuit including one of said secondaries and said tube, a filament current transformer, a filament circuit including the secondary of the filament curn rent transformer and the iilament in said tube, a circuit from said source of power to the primary of said filament current transformer, a rheostat in said last mentioned circuit, a selector device, a plurality of other rheostats, an absorption circuit including the other of said secondaries, said plurality of rheostats and said selector device, said selector device causing said absorption circuit to receive the half waves not useful to energize said tube, and interlocks between said auto-transformer and one of the rheostats in said absorption circuit and the filament current transformer rheostat and the other rheostat in said absorption circuit for conjoint

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • X-Ray Techniques (AREA)
US314030A 1928-10-22 1928-10-22 Control of inverse voltage Expired - Lifetime US1963160A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US314030A US1963160A (en) 1928-10-22 1928-10-22 Control of inverse voltage
FR682923D FR682923A (fr) 1928-10-22 1929-10-08 Montage électrique pour l'alimentation des tubes à rayons x et des applications analogues
DEV25855D DE538384C (de) 1928-10-22 1929-10-15 Anordnung zur Erzielung einer gleichmaessigen Belastung eines Hochspannungstransformators
GB31588/29A GB342263A (en) 1928-10-22 1929-10-17 Improvements in and relating to the control of unilateral electric current consuming devices
BE364688A BE364688A (fr) 1928-10-22 1929-10-21 reglage de la tension inverse

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US314030A US1963160A (en) 1928-10-22 1928-10-22 Control of inverse voltage

Publications (1)

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US1963160A true US1963160A (en) 1934-06-19

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US314030A Expired - Lifetime US1963160A (en) 1928-10-22 1928-10-22 Control of inverse voltage

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US (1) US1963160A (de)
BE (1) BE364688A (de)
DE (1) DE538384C (de)
FR (1) FR682923A (de)
GB (1) GB342263A (de)

Also Published As

Publication number Publication date
GB342263A (en) 1931-01-19
FR682923A (fr) 1930-06-04
BE364688A (fr) 1929-11-30
DE538384C (de) 1931-11-26

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