USRE14752E - Protection device for electric circuits - Google Patents

Description

H. DE F. ARNOLD.

PROTECTION DEVICE FOR ELECTRIC CIRCUITS. APPLICATION FILED- ocr. so. 1911.

Reissued Nov. 18, 1919. 14,752.

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UNITED STATES PATENT on HAROLD DE FOREST ARNOLD, OF EAST ORANGE, NEw JERSEY, ASSIGNOB, BY MESNE ASSIGNMENTS, T0 WESTERN ELECTRIC COMTANY, INCOBPORATED,'A CORPORATION OF NEW YORK.

PROTECTION DEVICE FOR CIRCUITS.

Specification of Reissued Letters Patent. Reigsued Nov, 18, 1919.

Original No. 1,168,270, dated January 1 8, 1916, Serial No. 877,056, flledDeceinbcr 14, 1914 Application for reissue filed October 30, 1917. Serial No. 199,860. i

To all whom it may concern:

Be it known that I, HAROLD Dn Fonns'r ARNOLD, a citizen of the United States, residing. at East Orange, in the county of Essex and State of New Jersey, have 1nvented certain new and useful Improvements in Protection Devices for. Electric Circuits, of which the following is a full, clear, concise, and exact descriptlon.

This invention relates to a device for limiting the power which may be transmitted toa receiving circuit. Its object is to provide means whereby nopower in excess of a predetermined value can be transmitted to the protected circuit, however high the applied voltage may This object is accomplished by making use of the fact that two unilaterally conducting elements in series opposition in a circuit limit the current which may flow in either direction around that circuit. In order, however, that this limiting value shall not be zero, some current must flow in each element, and this flow is provided for bysupplyingthe elements with direct current from a source of electromotive force in a local circuit. Such a circuit will be a direct current shunt on each element, but by inserting a choke coil in series with the source of elec'tromotive force in the local circuit, this path is made to have a-hi h impedance to the alternating current whic may be transmitted is therefore limited to the' value of the direct current used to I polarize the elements.

The invention consists in two electric yalves, each consisting of an ,electmn-enntting cathode and an anode inclosed in an evacuated-tube, connected in multiple toa source of constant electromotive force ap-' plied to the valves in the usual direction so as to make the heated elements the cathodes,

and in connecti the cathodes of the valves to awinding 0 one transformer and the anodes to a winding of another'transformer,

the other windings of the transformers init is desired to transmit. The amplitude of the alternating current which are two es, each of which incloses a.

heated filament 2 and an electrode 3. The

filament 2 is heated in the usual manner from the battery 4;. These electric valves are connected in multiple to a battery 5 or other suitable source of. constant electromative force, so applied to the valves that the filament 2 becomes the cathode and the electrode3 the anode. The currents through the valves must be slightly greater than the maximum value of the alternating current which it is desired to transmit. The cathode 2 is an electron-emitting cathode preferably of the type knownas Wehnelt cathode. The anode 3 may be an electrode of any suitable kind, as for example, a metallic plate. Such vacuum tube device has the well known property of acting as a valve, permitflows through the tube only when the filament'is the cathode. w

The cathodes 2, Q are connected to the opposite terminals of a winding 6 of a trans- 7 former 7, and the anodes 3, 3 are connected eluding, respectively, circuits which arethus so inductively connected that power in excess of a given value cannot be transmitted from one of said circuits to the other.

The invention may be more readily understood by reference to the accompanying r less-than the'normal direct current throughto the opposite terminals of a a second transformer 9.. One battery 5 is preferablyconnected to the mid: dle' of the winding 6, and the other pole to the middle of the winding 8. This provides a asymmetrical arrangement in which the two v ves 1, 1 are connected in multiple to a source of direct current, each branch of'the multiple circuit including one-half of the winding 6, and electric valve 1 and one-half of the w1nding8. v

v The winding 10 of the transformer! 'and the winding 11 of the transformer 9 areincluded 'in the circuits which are thus inductively connected winding 80f pole of the 12 and 13, respectively, 7

through the transformers 7 and. 9 and at the same time protected against abnormal p wer from one of said circuits b i t i ted to the other c1rcuit. w

So-long as the amplitude of the alternat ng current 1n the valve circuit is somewhat the valves, the alternating currents are passed by the valves with negligible distorprevent the flow of alternatin tion. It .is, however, impossible to pass through the circuit in either direction an al-.

ternatmg current of amplitude greater than that of the steady direct current through the valves, since this would require a flow of current from the cathode to the anode in one of the valves, in which direction current cannot pass. In other words the alternating current in the valve circuit is equal to the variation indirect current through the valves, since the high inductance choke coil prevents the flow of alternating current in the battery branch, and therefore the'maximum alternating current is limited by the value of that direct current.

combination of a source of direct potential; two electric valves connected in multiple to said source of potential, each valve consisting of anelectron-emitting cathode and an 4 anode inclo'sed in an evacuated tube: windings connecting, respectively, said anodes and said cathodes; and two circuits inductively connected, respectively, to said windings.

2. In a protector for electric circuits, t e

combination of two electric valves each consisting of an electron-emitting cathode and an anode inclosed in an evacuated tube; two transformers one winding of each of which lies in a single circuit containing said valves;

and a source of constant electromotive forceconnected between the middle points of said windings. 1

3. In combination with a'source of power and a receiving circuit, a protector "forelectric circuits comprisi a source of constant electromotive force, an inductive branch conta said source, unilaterally conducting thermionic elements connected in multiple to said branch, each element consisting of an electron-emitting cathode and an anode in an evacuated vessel, transformer windings forconnecting together said anodes and said cathodes,-respect1vely, and other windings and a receiving circuit, a "protectorfor elecof said transformers for connecting said protector to said source of power and to said receiving circuit. f v

,' 4. In combination with a source of power tri'c circuits comprising a sourcemfconstant electromotive force, an inductive ranch con-* ta 'such source, unilaterally nducting ihbl'IIllOlllO 'elementsconnected in multiple ina to such branch, transformer windings for connectin said elements in multiple and other win ings of said transformers for connecting said protector to said source of power and to said receiving circuit.

5. In a current limiting device, the combination with a circuit having a plurality of branches, of a sourceof current in a portion of said circuit common to the branches, at least one of said branches having an electric valve therein, and means for substantially preventing change of rate of current flow in said common portion.

6. In a current limiting device, the combination with a circuit having a plurality of branches, of a source of current in a portion of said circuit common to the branches, at least one of said branches having an electric {valve therein, means 'for substantially preventing change of rate of current flow in said common portion, and means forapplying a variable electromotive force to at least .one of said branches.

. 7. In a current limiting device, the combination with a circuit having a plurali y of 4 branches, of a source of current in a p rtion of said circuit common to the branches, at least one of said branches having an electric valve therein, means forsubstantiall preventing change of rate of current ow in said common portion, an element in one of said branches, and means for applying a varying electromotive force to said element.

8. In an electric system, the'combination with a circuit having a plurality of branches,

of a source of current in a ortion of said circuitcommon to the branc es, a valve in each-of said branches and means for sub-' stantially keeping constant the flow of current in said common portion.

9. In a current limiting device, the combination with a line or circuit, of a source of current and a unilaterally conducting element therein, means in said.circui t for applying an electromotive force thereto, means or preventing the applied electromotive force from changin the rate of current flow ortion of sai circuit and means associate with-said circuit for transmitting currentsimilar in wave "form tosaid applied electmmotive force.

,10. In an electric system, a line or circuit comprising a source of constant direct current and a unilaterall conducting element, means in said line or circuit for applying an electromotive force thereto, a shunt circuit .upon said bilaterally conducting element and means associated with said circuit for transmittin a current similar in wave form to said app ied electromotive force.

12. In combination, a supply circuit, a"

cuit, said means comprising connections arranged to reduce the current throu h one of /said thermionic devices to zero w en said .15

impulses exceed-a predetermined value.

13. .In combination, a supply circuit, a load circuit, and means in circuit therebetween for protecting the load circuit against excessive current comprising a'plurallty of thermionic devices each having a cathode and an anode adapted to be-traversed by current in response .to impulses in said supply circuit, said means comprising connections whereby the current through one of said thermionic devices is reduced upon a predetermined increase of current through another of said thermionic devices.

14. Ina currentlimiting device, the combination with a circuit havlng a plurality of branches, of a-sourc'e of cu nt in a portion ofsaid circuit common tothe branches, at

least one of said branches having an electric valve therein, means for substantially preventing change of rate of current flow in said common portion, means for applying a variable electromotive force to 'atleast one of said branches, and means associated with said circuit for transmitting a current similar' in wave form to said applied electromotive force.

15. In an electric system, the combination with a circuit having a plurality of branches, of a source of current in a portion of said circuit common to the branches, a valve in each of said branches, means for substantially keeping constant the flow of current in said common portion, means for applying to.said circuit a variable electromotive force, and means associated with said circuit for transmitting a current similar in wave form to said applied electromotive force.

16. In combination, a supply circuit, a load circuit, and means in circuit therebe tween for protecting the load circuit against excessive current comprising two thermionic devices in opposition each having a cathode and an anode adapted to be traversed by current in response to impulses in said supply circuit, said means comprising connections whereby the current through one of said thermionic devices is reduced to zero upon a predetermined increase of current through the other of said thermionic devices.

17. A line adapted to; be traversed by impulses to be repeated and by disturbing impulses of greater value, an automatically restorableprotective device comprlsing a p1urality of thermionic devices each COIIIPIISlIIg an anode and a filamentary cathode, means for heating said cathodes to cause them to emit electrons, and means for supplying a potential to the electrodes of said t ermionic devices to render the same substantially

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