US1607141A - High-resistance secondary winding - Google Patents

Description

1,607,141 R. H. WAPPLER I HIGH RESISTANCE SECONDARY WINDING Nov. 16 1926.

{ iled March 23, 1923 I 1 III llll IIIIIIIIIIIIIIIIIIIIII A A l 1 1 I I l V V V Y V L5 I I I 7 I IN I Y5 N 2 Off Patented Nov. 16, 1926.

UNITED STATES RnINHoLn H. APPLER, on NEW "sonar, n. Y.,-Assrs-n0n r0 WAPPLER Ennc'rnro 001a- PANY, mo, or LONG ISLAND orrY, new Yon-K, e oonronerrrort or NEW YORK.

HIGH-RESISTANCE SECONDARY WINDING.

Application filed March 23, 1922'.

My invention relates to means for preventing the development ot undue amperages in certain kinds o1 circuits n which high tension'currents are supplied by thesecondary winding of a transformer.

hloreparticularly stated I seek to use, in the secondary winding, a high ohmic resist ance of such character and so distributed as to remain constanteven when subjected to very high potentials.

For the purpose here contemplated I make the secondary winding of a material the specific resistance of which is much greater than the specific resistance of copper, or I make the secondary winding partly of copper and partly of a material having a specific resistance higher than that of copper. Thus in either case confer upon the secondary winding as a whole a specific resistance higher than that of copper wire. German silver or any of the alloys used for resistance wire may be employed as the material of the secondary winding;

In a secondary circuit used for X-ray work, it is necessary to limit the current employed, while developing very hlgh potentials. Much depends, however, upon the manner in which the current is thus limlted. Ittliere be inserted in the circuit one or more resistance units in which the ohmic resistance is very high, the resistance offered by the unit or units does not remain constant, especially at high potentials. As a matter of fact, practically any sort of resistance unit in the relation here contemplated, is utterly unreliable at high potentials. I find, however, that the ohmlc resistance of the unit or units may be rendered both constant and reliable if it be made in the manner here contemplated, namely, by increasing the internal resistance of thesecondary winding, by making the. wlnding of wire having a high specific reslstance.

In the use of high potential transformers, and especially those used in X-ray work, there is great difiiculty in holding back an excess of current.-. It for instance itis desired to produce X-raylsot a certain-dosage, it becomes necessary to prevent the increased flow of. current which otherwise happens: inevitably,.'.owing to' the changes taking place- :in. theX-ray tube-:itselt, when I subjectedto'highupotentialsz Therefore itis obvious that i by limiting, the flow ofl' c'u'r- Serial No.- 546,141.

rent throughout the entire length of the secondary circuit, or at least throughout a predominating portion thereot, we develop better conditions for maintaining constancy in the density and power of the radiation. No matter how any number of separate resistances may be arranged in the primary circuit, these resistances do not have as good an efiect, for the purposes here contemplated, as an internal resistance embodied in the secondary winding and distributed through* out all or the greater portion of the length thereof.

I find, moreover, that by arranging the resistance as above suggested the secondary winding may be caused to generate currents similar in character to those of a static machine in which the internal resistance is enormously high. Such being the case, by producing currents of the kin-d here contemplated,- rectifying such currents, and causing them to produce a discharge, the apparatus can be substituted for. a static machine.

The principle of my invention may perhaps be more easily understood by bearing in mind in X-ray work the potentials may easily run up to several hundred thousand volts; and at an instant while the voltage is very high (perhaps at or near its highest peak), the internal resistance of the X-ray tube may suddenly drop, and by so doing invite a rush of current through the tube and thus through the secondary winding; whereas by the use of my invention the cur rent which can develop is necessarily kept very small, even it the ohmic resistance of the X-ray tube suii'ers, an enormous drop.

Again, by the useot-my invention in high potential transtorn'ier, the current value of the high potential currents gen erated by the transformer maybe limited within reasonable bounds by the inherent characteristic of the secondary winding, so no matter how high may be the voltages employed there can never under any circumstances be an excessoi' current; and this desirable result is attained without the adsimple X' ray system including. a represeniii) tative form of my high resistance secondary winding.

A high tension transformer l, in this instance s iitablc for Y-ray work, is provided with a primary windimr 2 and a secondary winding The primary winding 2 may be of the usual or any preferred construction, anc is connected by wi e 4: and a sliding connection 5 with a pair of leads 6 and 7, the latter being connected with an alternating current generator 8, by aid whereof the primary winding 2 nergized.

By means of the sliding connection 5 the number of turns in the primary winding, effective for iergizing the transformer,may be varied at the will of the operator, and the transformation ratio may be changed accordingly.

The transformer may be oil-insulated, if desired, the form of the insulation being no part of my invention.

The secondary winding 3 is by means of wires 9 and 10 connected with brushes 11 and 12. These brushes are mounted upon a rectifying switch 18, provided with sectors 14 and 15 of conducting material. The rectifying switch 13 may be of the usual or any preferred construction, and is synchronously driven. The rectifying switch 13 is provided with two brushes l6 and 17, and from these brushes two wires 18 and 19 lead to an X-ray tube 20.

lVhile the particular X-ray tube here shown is an ordinary tube, it will be understood that any other tube, such for in stance as a tube of the Lilienfeld type or of the Coolidge type may be employed in stead.

The secondary winding 3 consists of an insulated wire made of conducting material the specific resistance of which is higher than that of copper; as, for example, German silver or any suitable resistance alloy. Preferably the wire of the secondary winding is of uniform diameter throughout the entire length of the winding, so that the ohmic resistance of the winding is rendered uniform from one end of the winding to the other.

In some instances I make the secondary winding partly of wire of the kind just described and partly of copper wire, but in any event the mean specific resistance of the secondary winding as a whole is higher than if the entire winding wire made of copper wire of the same gauge.

By means of the secondary winding made as above described, very high potentials may be developed and yet the current values may be maintained relatively low. 1

When an X-ray tube is energized by means of this apparatus, the discharge through the tube is of the type known in this art as a fine spray discharge.

I have made the discovery that if X-rays are employed for therapeutical purposes, and are made by aid of the apparatus above described, the magnitude of the ohmic resistance of the secondary winding may become quite an important factor in the eflicacy of the treatment. For instance, ordinarily in treating an infected tonsil the ohmic resistance of the secondary winding should be different from that required for treating a deep seated organ afiiicted with cancer.

In working with X-ray tubes and some other kinds of vacuum tubes, it is often desirable to prevent the development of oscillations; This point is of great importance in connection with the operation of X-ray tubes. Where oscillations are developed the heating of the tube and the danger of a breakdown are greatly increased. Moreover, the oscillations tend to render the action of the tube freakish, and also to interfere with uniformity in the penetration of the X-rays produced.v

As is well known in this art, the development of oscillations in a given circuit is dependent, mainly at least, upon the relations of the inductance, capacity, and ohmic resistance, usually designated as the constants, of the circuit. It is therefore practicable to prevent oscillations from taking place in a high tension circuit for energizing an X-ray tube, by suitably apportioning the inductance, capacity, and ohmic resistance. I find, however that by far the best way to prevent the development of oscillations in this connection is to use a sufiiciently high ohmic resistance of the kind above described.

A great advantage possessed by a high potential transformer made in accordance with my invention is, that the transformer contains inherently within itself themeans for preventing the development of an excess of current, even when very high potentials are employed; This dispenses with all necessity for inserting a resistance unit of any kindin series with the secondary winding, and consequently does away with all necessity for ehanging'such resistance unit from time to time and under varying conditions, in order to avoid excess of current.

I do not limit myself to the precise mechanism shown and described, as variations may be made therein without departing from my invention the scope of which commensurate with my claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is as follows:

1. In a device of the character described the combination, with a vacuumtube and a rectifying switch for rectifying high tension currents used for making discharges through said tube, of a transformerprovided with a high tension secondary winding connected with said rectifying witch, said high tenlll) sion secondary winding having its internal resistance high enough to prevent the development of oscillations in the secondary circuit.

2. In a device of the character described the combination, with a vacuum tube and means for rectifying high tension currents for making discharges through said vacuum tube, of a transformer provided With a high tension secondary Winding, said secondary Winding being connected with said rectifying switch and In ving an internal resistance high enough to prevent the development of oscillations in the secondary circuit, said transformer being further provided With a primary Winding, and means controllable by the operator for varying the number of turns of the primary Winding effective for energizing the transformer.

3. In a device of the character described the combination, With a vacuum tube and means for rectii'yin high tension currents used for making discharges through said vacuum tube, of a transformer provided with a high tension secondary Winding for energizing said vacuum tube, said high tension secondary Winding having its internal resistance high enough to prevent the development of oscillations in said vacuum tube, said transformer being further provided With aprimary Winding whereby said transformer is energized.

REINHOLD H. \VAPPLER.

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