US2039057A - Electric valve circuits - Google Patents

Description

Apriii E J @LARK waiiflg? ELECTRIC VALVE C IRCUITS Filed Oct. 6, 1934 Invemtov: Earl J. Clark H is Attorhe j- Patented Apr. 28, 1936 ELECTRIC VALVE CIRCUITS Earl J. Clark, Chestnut Hill, Mass, assignor to General Electric Company, a corporation of New York Application October 6,

12 Claims.

My invention relates to circuits for hot cathode electric discharge devices and particularly to circuits including vapor electric valves.

In order to obtain the most satisfactory and 5 eflicient operation, as well as the long life so desirable in a hot cathode discharge device, it is necessary that the emissivity of the cathode and the vapor pressure be great enough to meet the requirements of the device before the normal load circuit is connected thereto. If the normal anodecathode voltage is applied to the valve before the vapor pressure and the temperature of the valve reaches the proper value, much of the activating material of the cathode will be lost from its surface, the effect of which is to destroy the electron emitting properties of the cathode. This --deleterious effect is particularly noticeable in electric valves of the vapor electric discharge type, which rely primarily for their operation upon the :0 ionization of the contained vapor. In this type of valve if the normal voltage is impressed between anode and cathode during the period in which the cathode temperature and the vapor pressure is relatively low, excessive cathode disintegration is 55 caused by positive ion bombardment.

One object of my invention is to provide an improved apparatus for preventing excessive cathode disintegration during the starting operation of an electric discharge device.

50 Another object of my invention is to provide in a translating circuit for electric valves means whereby the load current is increased in predetermined steps.

A further object of my invention is to provide 35 an improved method and means for connecting a multi-anode electric valve into a translating circuit.

In accordance with my invention I provide in translating circuits employing multi-anode vapor in electric valves, or a plurality of single anode valves, means for progressively connecting the operating potential to the anode circuits after each valve has attained a predetermined degree of conductivity. This method of connecting the 45 anode circuits provides additional protection for the vapor electric valves inasmuch as the entire load is not applied to the valve in one step. The means employed to initiate the progressive application of load may be directly responsive to the 50 cathode temperature and vapor pressure or responsive to an electrical condition of the electric discharge device, or responsive to an electrical condition of an associated circuit. In the illustrated embodiment of my invention I use electro- 55 magnetic switch apparatus in an auxiliary circuit 1934, Serial No. 747,177

to control the connection of the source of normal voltage to the discharge device after the-current in the auxiliary circuit reaches a predetermined magnitude. It will be understood that as the temperature of the cathode and the vapor pres- 5 sure increases, with a definite low starting voltage applied, the current in an auxiliary starting circuit will increase. The rate at which the current in such an auxiliary circuit increases will, of course, depend upon the characteristics of the particular space discharge device. In a vapor electric valve, the value of the current which the valve will conduct for a definite applied voltage may be used to indicate the condition of the valve with respect to the ionization of the vapor and the number of electrons emitted from the cathode which determine the degree of conductivity of the valve. It is then, possible to prescribe the value of the current or the degree of conductivity of the valve at Which the normal operating voltage will be applied. When such a condition is satisfied, this condition may be used to initiate the gradual application of the load to the valve.

My invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the single figure of the accompanying drawing which is a diagrammatic representation of one embodiment of my invention, I have shown an arrangement which is applicable to a full wave rectifier valve for supplying a direct current load circuit. A transformer I, energized from an alternating current supply source 2 furnishes energy to a direct current load circuit 3 through electromagnetic switching relays 4 and 5 and a full wave rectifier valve 6. The transformer I is provided with a primary winding "I, a secondary winding 8 for energizing the cathode of the valve 6, a low voltage starting winding 9 and a normal operating voltage winding I0. One of the electromagnetic switches 4 has an operating winding II and two pairs of contacts I2 and I3 arranged to be closed by the armature I4 which is normally biased so as to close the contacts I3. The other electromagnetic switch 5 has a current responsive operating winding I5, a retaining winding I6 and three contacts I'I, I8 and I9, arranged to be connected together by an armature 20 upon energization of the winding I5. Thefull wave rectifier valve 6 may be of any of the incandescent cathode types commonly known in the art, but preferably is of the vapor electric discharge type having a cathode 2| and two anodes 22 and 23.

Energization of the winding 1 may be effected through a suitable switch 24. Due to the fact that the armature I4 of electromagnetic switch 4 is biased so as normally to close the contacts 13, the low voltage starting winding 9 is connected therethrough to the anode 23 of the electric discharge device 6. The other side of the low voltage winding 9 is connected through the current responsive winding 15 of the electromagnetic switch 5 and a suitable current limiting resistor 25 to the cathode 2| of the discharge device 6. As will be apparent later, the current responsive winding l5 of the switch 5 will become energized after a predetermined time interval to actuate the armature 20 to connect together the contacts ll, l8 and i9. Two of the contacts 11 and I8 are connected respectively to the anode 22 of the discharge device and one terminal of the transformer secondary winding ID. The other contact IQ of the relay 5 is connected through the retaining winding l6 thereof to the winding ll of the relay 4, which in turn is connected to the other terminal of the high voltage winding In of the transformer I. When a circuit from the normal operating winding ID of the transformer l is completed through the contacts 18 and IQ of the switch 5, the relay winding N5 of the switch 5 and the relay winding ll of the switch 4 become energized so as to hold the armature of the switch 5 in its closed position and to attract the armature of the switch 4 so as to close the contact l2 thereof, thereby connecting the anode 23 of the discharge device 6 to the other terminal of the transformer winding ID.

The operation of the apparatus shown in the drawing may be explained as follows. Prior to and immediately after the energization of the transformer I, the switch 4 through armature l4 and contacts l3, connects the low voltage winding 9 to cathode 2| and anode 23 through an auxiliary load circuit. This auxiliary load circuit is com pleted from one side of the transformer winding 9 through the valve 6 from anode 23 to cathode 2|, through a current limiting resistor 25 and winding l5 of switch 5 back to Winding 9. When the current in the auxiliary circuit reaches a predetermined magnitude, a suitable value being selected in accordance with the magnitude of the voltage applied and the cathode temperature and vapor pressure at which it is desired to apply the normal voltage, the switch 5 is actuated by winding l5, the armature 20 of which bridges contacts IT, IS and a terminal I 8 to connect terminal l8 of the normal voltage transformer winding III to the anode 22 of the valve 6.

At this point in the starting sequence it is seen that energy is being supplied to load circuit 3 from only one-half of winding III. For the purpose of explanation let it be assumed that the instantaneous voltage of winding I0 is such that current will flow from one-half of winding ll] through switch armature 20 and contact l1, through valve 6, by the way of anode 22 and cathode 2| to the load circuit .3 and then back to the midpoint of transformer winding l0. When armature 20 of relay 5 bridges contacts l1, l9 and terminal I8, holding winding l6 of switch 5 and a holding and actuating winding l I of switch 4 are energized from the transformer winding 10, armature I4 is raised, disconnecting contacts l3 and bridging contacts l2, thereby opening the auxiliary circuit and connecting anode 23 of the valve 6 to the other half of winding l0. After switch 4 has been actuated, it is apparent that both anodes 22 and 23 are connected in the translation circuit and that both anode circuits are supplying current to the load circuit 3. So long as normal voltage conditions prevail it will be seen that the retaining windings I 6 and II of switches 5 and 4, respectively, will retain the circuit in this condition.

As will be readily understood, upon deenergization of the transformer, both switches 4 and 5 will automatically return to their normal positions and upon a subsequent reenergization of the transformer the same starting sequence of operation will follow automatically.

It is further evident from the above description that the normal operating voltages have been applied to the anodes in progressive order, thereby obtaining a gradual increase of the load current supplied by the valve.

To those skilled in the art it is evident that I may, without departing from the true scope of my invention, apply my invention to translation circuits generally, whether of the vacuum or vapor electric valve types.

While I have described what I at present consider the preferred embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made Without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a supply circuit, a load circuit and a translating circuit interconnecting said circuits including a valve having a plurality of anodes for supplying said load circuit, a source of normal operating potential, a source of reduced potential, means for initially connecting said source of reduced potential to one of said anodes, and means responsive to the current flowing in said last mentioned circuit for successively connecting said anodes to the source of normal potential.

2. In a translating circuit, an electric valve having a plurality of anodes, a plurality of circuits of normal operating potential arranged to be connected to said anodes, a source of potential having a value less than the potential of said plurality of circuits, means for initially connecting said source of potential to one anode circuit, and means responsive to a predetermined degree of conductivity of said valve for connecting the anode circuits in the translating circuit in a predetermined sequence.

3. In combination, a supply circuit, a load circuit and an electric translating circuit connected therebetween and including an electric valve provided with a plurality of anodes and a thermionic cathode, a source of normal operating potential, a source of reduced potential, means for initially connecting said source of reduced potential between one of said anodes and said cathode, and means responsive to a predetermined degree of conductivity of said valve for connecting said source of normal operating potential to said anodes.

4. The method of energizing the anode-cathode circuits of an electric valve of the type having a plurality of anodes and a thermionic cathode, which consists in energizing a heating circuit for said cathode, applying a reduced potential between one anode and said cathode and subsequently applying the normal operating potential conductivity of the valve reaches a predetermined value.

5. The method of energizing the anode-cathode circuits of an electric valve of the type having a plurality of anodes and a thermionic cathode, which consists in energizing a heating circuit for said cathode, applying a reduced potential between one anode and said cathode and successively applying the normal operating potential between the cathode and the various anodes when the conductivity of the valve reaches a predetermined value.

6. In combination, an electric translating circuit including an electric valve provided with a plurality of anodes and a thermionic cathode, a source of normal operating potential, a source of reduced potential, an auxiliary circuit, means for initially connecting said source of reduced potential to one anode and the cathode through said auxiliary circuit, and means responsive to an electrical condition of the auxiliary circuit for initiating the application of load by connecting the normal operating potential to the anodes in a predetermined sequence.

7. An apparatus for transmitting energy from an alternating current circuit to a direct current circuit, comprising a transformer network provided with sources of normal operating anodecathode potential and a neutral point and a source of reduced potential, a vapor electric valve provided with a plurality of anodes and a thermionic cathode, a direct current load circuit connected between the said transformer neutral point and the said cathode, means for initially connecting the said source of reduced potential between one anode and said cathode, and means responsive to a predetermined degree of conductivity of said valve for initiating the successive connection of the sources of normal operating potential between the anodes and the cathode.

8. An apparatus for transmitting energy from an alternating current circuit to a direct current load circuit comprising a transformer network provided with sources of normal operating anode-cathode potential and a neutral point and a source of reduced potential, a vapor electric valve provided with a plurality of anodes and a thermionic cathode, an auxiliary circuit, a direct current load circuit connected between the transformer neutral point and said cathode, means for initially connecting said source of reduced potential to one anode and the cathode through said auxiliary circuit, and means responsive to an electrical condition of said auxiliary circuit for initiating the application of load by connecting the sources of normal operating potential to the anodes in a predetermined sequence.

9. In combination, a supply circuit, a load circuit and an electric translating circuit connected therebetween and including an electric valve provided with a plurality of anodes and a thermionic cathode, a source of normal operating potential, a source of reduced potential, means for initially connecting said source of reduced potential between one of said anodes and the cathode, and means responsive to a predetermined degree of conductivity of said valve for connecting said source of normal potential to said anodes and for disconnecting said source of reduced potential.

10. In combination, a supply circuit, a load circuit and an electric translating circuit connected therebetween and including an electric valve provided with a plurality of anodes and a thermionic cathode, a source of normal operating potential, a source of reduced potential, means for initially connecting said source of reduced potential between one of said anodes and the cathode, and means responsive to a predetermined degree of conductivity of said valve for connecting said source of normal potential to said anodes and for subsequently disconnecting said source of reduced potential.

11. In combination, a supply circuit, a load circuit and an electric translating circuit connected therebetween and including an electric valve provided with n anodes and a thermioniccathode, 11 sources of normal operating potential to be connected to said anodes, a source of reduced potential, means for initially connecting said source of reduced potential between one of said anodes and said cathode, and means responsive to a predetermined degree of conductivity of said valve for connecting each of the (n1) sources of normal potential to a predetermined one of the remaining (n1) anodes and for energizing said first mentioned means to disconnect said source of reduced potential and to connect the remaining source of normal potential to said one anode.

12. In combination, a supply circuit, a load circuit and an electric translating circuit connected therebetween and including an electric valve provided with n anodes and a thermionic cathode, n sources of normal operating potential to be connected to said anodes, a source of reduced potential, means for initially connecting said source of reduced potential between one of said anodes and said cathode, and means responsive to a predetermined degree of conductivity of said valve for connecting each of the (IL-1) sources of normal potential to a predetermined one of the remaining (n1) anodes and for energizing said first mentioned means to disconnect said source of reduced potential and subsequently to connect the remaining source of normal potential to said one anode.

EARL J. CLARK.

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