US2155251A

US2155251A - Electric valve circuits

Info

Publication number: US2155251A
Application number: US165143A
Authority: US
Inventors: Burnice D Bedford
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1937-09-22
Filing date: 1937-09-22
Publication date: 1939-04-18
Anticipated expiration: 1956-04-18

Description

April 18, 1939. B BEDFORD 2,155,251

ELECTRIC VALVE CIRCUITS Filed Sept. 22, 1937 2 Sheets-Sheet 1 1] 1. Fig.1. tin

Inventor:

Burnice D. BedEO d, by WW6 X9 Hi5 Attorney April 18, 1939.

BL D. BEDFORD ELECTRIC VALVE G IRCUITS Filed Sept. 22, 1957 2 Sheets-Sheet 2 Inventor: Buvnice D. Bedford,

. His Attorney.

all]

Patented Apr. 18, 1939 UNITED STATES ELECTRIC VALVE CIRCUITS I Burnice D. Bedford, Schenectady, N. Y., assignor to General Electric Company, a corporation 01' New York Application September 22, 1937, Serial No. 165,143

11 Claims.

My invention relates to electric valve circuits and more particularly to excitation or control circuits for electric valve apparatus.

In the control of electric valve apparatus where the apparatus is rendered conductive periodically upon the application of a suitable control voltage to an associated control member, it has been found that it is highly important to provide arrangements whereby the control member is energized in the desired manner during transient load conditions or during transient disturbances. For example, in electric valve systems such as inverter systems, it has been found that during transient conditions the voltages impressed on the control members vary considerably so that the electric valve means is not controlled in the desired manner, resulting in many instances in very perceptible variations in output characteristics and in some instances in interruption of service. There has been evidenced a decided need for auxiliary apparatus to be used in connection with the excitation circuits for the electric valve means to assure positive and suitable energization of the control members during the transient disturbances.

and assigned to the assignee of the present invention.

It is an object of my invention to provide a new and improved electric valve circuit.

It is another object of my invention to provide new and improved control or excitation circuits for electric valve apparatus.

It is a further object of my invention to provide new and improved control systems for electric valve apparatus in which there is assured suitable and positive energization of the control members of the electric valves during transient load conditions or during transient disturbances caused by extraneous conditions.

In accordance with the illustrated embodiments of my invention, I provide new and improved excitation systems for electric valve apparatus, particularly electric valve inverting apparatus. Although not limited thereto, I have chosen to show my invention as applied to electric valve apparatus used in a constant current direct current transmission system of the type disclosed and claimed in the above mentioned Stone patent. Suitable apparatus, such as rotating dynamo-electric machines of the induction type, are connected across the terminals of the excitation circuits to supply to the excitation circuits a balanced polyphase system of voltages during transient conditions. During normal operation of the electric valve system and during the time in which a source of current for the excitation circuits operates normally, the dynamoelectric machine operates as a motor energized from the source. Upon the occurrence of some irregularity or upon the occurrence of sudden application of load, efiecting an unbalance of the voltages of the source and causing a substantial reduction in the values of the voltage, the dynamo-electriomachine operates as a generator to impress on the excitation circuits suitable alternating voltages, to assure positive and reliable control of the electric valves during such disturbances.

In accordance with another embodiment of my invention, there is provided an excitation system for electric valves used in systems for effecting transmission of energy between constant current alternating current circuits and direct current circuits. The excitation circuits of the system are energized from the constant current alternating current circuit and a dynamo-electric machine is connected across the terminals of the excitation circuits to efiect application of suitable alternating voltages during transient conditions.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims. Figs. 1, 2 and 3 represent various modifications of my invention as applied to electric valve systems for transmitting energy from a constant voltage alternating current circuit to a constant current direct current circuit,

or vice versa.

Referring now to Fig. 1 of the accompanying drawings, there is represented an embodiment of my invention as applied to an electric valve translating system for transmitting energy between a constant voltage alternating current circuit including conductors l, 2 and 3 anda constant current direct current circuit 4 through electric valve means 5l0. The electric valve means 5-H! are preferably of the type employing an ionlzable medium, such as a gas or a vapor, and each includes an anode II, a cathode l2 and a control member l3. To efiect transformation of the constant voltage alternating current to alternating current of constant value, or vice versa, I provide a suitable means such as a monocyclic network including a plurality of branches of serially connected reactances of opposite sign, such as capacitances |4, I5 and I6 which are respectively connected in series relation with inductances l1, l8 and I9. Each of the branches is connected across a different phase of the constant voltage alternating current

circuit including conductors

2 and 3. As an agency for effecting proper voltage transformation between the constant current circuits of the monocyclic network and electric valves 5-|0, and for con necting the constant current circuits to the electric valves, I employ a transformer 20 having primary windings 2| and

secondary windings

22, 23 and 24. In order to eifect an improvement in apparatus economy, I connect secondary windings 22-24 to the constant current terminals of the monocyclic network in the manner described and claimed in my copending patent application Serial No. 97,011, filed August 20, 1936 and assigned to the assignee of the present application. Excitation circuits 25-30, inclusive, are associated with electric valve means 5-|0, respectively, and serve to impress on the associated control members l3 alternating voltages to render the electric valves conductive in a predetermined order to effect transmission of energy between the constant current circuits and the constant current direct current circuit 4. Each of the excitation circuits 25-30 is similar in construction and arrangement, and to facilitate description thereof excitation circuit 25 will be considered in particular. If it is desired to impress on the control member |3 an alternating voltage of peaked wave form, I may employ any suitable arrangement such as a peaking transformer 3| of the saturable type which has a core member 32 provided with a restricted saturable portion 33, a primary exciting winding 34 and a control winding 35 in which there is induced an alternating voltage of peaked wave form. A parallel unidirectional conducting device 38 and a noninductive impedance, such as a resistance 31, may be connected in series relation with the winding 35 and control member l3 to offer a relatively low impedance to the flow of normal control member current and to offer a relatively higher impedance to the flow of control current incident to the deionization of the medium in electric valve 5. A capacitance 38 may be connected between the control member I3 and cathode |2 to absorb extraneous transient voltages.

To impress on the control member l3 a negative unidirectional biasing potential, I employ a self biasing type of circuit including a parallel connected capacitance 39 and a resistance 40. The resistance 40 may be of a material having a nonlinear impedance-current characteristic, such as the material disclosed and claimed in United States Patent 1,822,742 granted September 8, 1931 on an application of Karl B. McEachron and assigned to the assignee of the present invention. The excitation circuits are described in my copending application Serial No. 88,825 filed July 3, 1936 and assigned to the assignee of the present application.

Excitation circuits 25-30 may be energized from any suitable source of alternating current of proper frequency, and in the arrangement shown in Fig. 1 the excitation circuits are energized from the constant voltage alternating current circuit through a transformer 4| having primary windings 42 and secondary windings 43. To adjust the phase of the voltages impressed on the control members l3, any suitable arrangement such as a rotary phase shifter 44 may be interposed between the source of alternating current and the excitation circuits. As an agency for supplying to the excitation circuits, during transient disturbances, a polyphase system of voltages, I have illustrated an energy storage device such as a dynamo-electric machine 45 which may be of the induction type having stator or inducing windings 45 and having a rotor member 41. It is to be understood that the rotor may be of the wound type or that the rotor may be of the squirrel cage type. To suppress or diminish the intensity of the voltage disturbances which may be present in the constant voltage alternating current circuit or which may be present in an auxiliary source when used, I provide suitable reactive impedances connected between the source and the excitation circuits and machine 45. Resistances 49 may also be connected in series relation with the inductances 48 to provide a net impedance of relatively high value to prevent the transfer of appreciable energy from the dynamo-electric machine 45 to windings 43 of transformer 4| during the occurrence of transient disturbances in the constant voltage circuit.

The general principles of operation of the embodiment of my invention shown in Fig. 1 will be explained when the electric translating system thereof is operating to transmit energy from the constant current direct current circuit 4 to the constant voltage alternating current

circuit including conductors

2 and 3. The electric valves 5-|0 are rendered conductive in a predetermined order and for predetermined recurring intervals of time, each substantially electrical degrees, to supply alternating current of constant value to the monocyclic network through transformer 20, and the monocyclic network transforms the alternating current of constant value to constant voltage alternating current. The excitation circuits 25-30 are energized from the constant voltage circuit, and the phase of the alternating voltages of peaked wave form impressed on control members 3 may be adjusted by means of the rotary phase shifter 44.

So long as the system operates in the regular or normal manner, the dynamo-electric machine 45 will operate as a motor energized from the constant voltage circuit through transformer 4|. If, for example, due to some irregularity of operation or because of a sudden application of load, the polyphase system of voltages impressed on the excitation circuit becomes unbalanced or decreases materially, the dynamo-electric machine 45 will temporarily act as a generator to impress on the excitation circuits a balanced polyphase system of voltages. Due to the presence of the reactive impedances 48 and resistances 49, only a small amount of the current supplied by the machine 45 will be transmitted to the transformer 4| and the greater portion of the stored energy of the machine 4| will be utilized in supplying excitation currents to the excitation circuits 25-30. In this way, the system responds to assure positive and suitable excitation of the control members l3 of electric valves 5-|0 even through the supply source for the excitation circuits temporarily fails to effect proper energization thereof.

Fig. 2 represents another embodiment of my invention applied to an electric valve translating system of the same general type shown in Fig. 1, and corresponding elements have been as signed like reference numerals. A constant current alternating current circuit, including conductors 50, 5| and 52, is shown as being connected between the monocyclic network and the electric valves 5-! 0, and the excitation circuit 28 for electric valve 8 is energized from the constant current alternating current circuit through current responsive devices 53, 54, and 55 and a suitable phase shifting arrangement such as a rotary phase shifter 56. The output circuit of the rotary phase shifter 56 supplies a balanced polyphase system of voltages through

conductors

51, 58 and 59. Although only excitation circuit 28 for electric valve 8 is shown, it is to be understood that the excitation circuits for the other electric valves are connected to

conductors

51, 58 and 59 in the usual manner to effect the proper energization of the respective control members. The dynamo-electric machine 45 is connected across the output terminals of the rotary phase shifter 56 and serves to supply a balanced system of polyphase voltages in the event the constant current alternating current circuit departs or deviates from normal operation.

The operation of the arrangement shown in Fig. 2 will be briefly described. The energization of excitation circuit 28 is obtained from the constant current alternating current circuit including conductors 50-52 through the transformers 53-55 and phase shifter 56 which impress on exciting winding 34 of transformer 3| an alternating voltage. During transient load conditions or during transient disturbances, if the current in conductors 50-52 deviates from the normal mode of variation the dynamo-electric machine 45 will act as a generator to impress on winding 34 of transformer 3| a suitable alternating voltage of proper magnitude, thereby assuring proper energization of control member I3 of electric valve 8. Of course, the other excitation circuits (not shown) will be energized in like manner.

In Fig. 3 there is shown another embodiment of my invention as applied to a system which is substantially the same as that shown in Fig. 1, and corresponding elements have been assigned like reference numerals. A transformer 60, having primary windings 6| and secondary windings 62, is connected between the electric valves 5-I 0 and the monocyclic network. The elements of the arrangement of Fig. 3, where common to corresponding elements of Fig. l, have been assigned like reference numerals.

As an arrangement for energizing the excitation circuit 28 and the other excitation circuits (not shown) during transient conditions, I provide a high impedance network 63 connected between the stator windings 46 of machine 45 and the transformer 4|. The network 63 may comprise a plurality of branches of reactive impedances, such as capacitances 64, inductances 65 and may include adjustable resistances 66. The network 63 suppresses or diminishes the transient voltage disturbances which may be communicated to the transformer 4| from the constant voltage circuit including conductors l-3. Transformers 61, 6B and 69 are connected in series relation with output conductors 10, H and 12 of rotary phase shifter 44 to impress on the excitation circuits for electric valves. 5-10 a polyphase system of alternating voltages derived from the dynamoelectric machine 45 during transient disturbances. Primary windings 13 of transformers 61-69 are connected across the terminals of windings 46 of machine 45 and points of the adjustable resistances 66. I

The operation of the arrangement shown in Fig. 3 is substantially the same as the arrangement shown in Figs. 1 and 2. During transient disturbances of the system, the dynamo-electric machine 46 will operate as a generator to impress on the excitation circuits for electric valves 5-10 a polyphase system of voltages to assure accurate and positive control of the electric valves. The high impedance network 63 prevents the voltage disturbances of the constant voltage circuit from being reflected to the excitation circuits and also prevents an appreciable portion of the energy of the dynamo-electric machine 45 from being transferred to transformer 4|. Because of the mechanical and electrical stored energy of machine 45, the machine 45 responds to assure energization of the excitation circuits dur ing transient voltage disturbances and during temporary failure of the source of energization.

While I have shown and described my invention as applied to a particular system of connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that 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, electric valve means connected between said circuits for transmitting energy therebetween, said electric valve means having a control member, an excitation circuit comprising a source of alternating voltage for impressing on said control member a control voltage, and energy storage means comprising a dynamo-electric machine for introducing into said excitation circuit an alternating voltage during transient conditions to assure energization of said control member during transient voltage disturbances of said source.

2. In combination, a supply circuit, a load circuit, electric valve means connected between said circuits for transmitting energy therebetween, said electric valve means having a control member, a source of alternating voltage, an excitation circuit connected to said source for impressing an alternating voltage on said control member, and energy storage means connected to said source and to said excitation circuit and being arranged to receive energy from said source dur ing normal conditions of operation thereof and being arranged to impress an alternating voltage on said control member in event said source fails temporarily.

3. In combination, a supply circuit, a load circuit, electric valve means connected between said circuits for transmitting energy therebetween, said electric valve means having a control member, a source of alternating voltage, an excitation circuit having input terminals thereof connected to said source and arranged to impress an alternating voltage on said control member,

nating voltage for energizing said excitation circuit, and energy storage means comprising an alternating current dynamo-electric machine of the induction type connected across said excitation circuit and being arranged to operate as a motor when said excitation circuit is energized from said source and being arranged to supply alternating voltage to said excitation circuit during transient voltage disturbances of said source.

5. In combination, a constant voltage alternating current circuit, a direct current circuit, a constant current alternating current circuit connected to said constant voltage circuit, electric valve means connected between said constant current circuit and said direct current circuit, said electric valve means having a control member for controlling the conductivity thereof, an excitation circuit for said control member, means energized in accordance with the current of said constant current circuit for impressing an alternating voltage on said excitation circuit, and a dynamo-electric machine connected to said excitation circuit and being arranged to operate as a motor when said excitation circuit is energized from said constant current circuit and being arranged to impress an alternating voltage on said excitation circuit in the event the constant current circuit temporarily fails to energize said excitation circuit.

6. In combination, a constant voltage alternating current circuit, a constant current direct current circuit, means connected to said constant voltage circuit and comprising a plurality of serially connected reactances of opposite sign for transforming constant voltage alternating current into alternating current of constant value, a constant current alternating current circuit connected to said means, electric valve means connected between said constant current alternating current circuit and said direct current circuit, said electric valve means being provided with a control member for controlling the conductivity thereof, an excitation circuit for energizing said control member, a current transformer connected in said constant current alternating current circuit for energizing said excitation circuit, and a dynamo-electric machine of the induction type connected to said excitation circuit and being arranged to operate as a motor when said excitation circuit is energized from said constant current alternating current circuit and being arranged to supply voltage to said excitation circuit when said constant current alternating current circuit temporarily fails to enerize said excitation circuit.

7. In combination, an electric valve means having a control member, an excitation circuit for said control member, a source of alternating voltage for energizing said excitation circuit, a high impedance network connected to said source, a dynamo-electric machine connected to said excitation circuit and connected to be energized from said source through said network, and means responsive to the voltage of said dynamoelectric machine for introducing into said excitation circuit an alternating voltage when the voltage of said source undergoes transient disturbances.

8. In combination, an electric valve means having a control member, an excitation circuit for energizing said control member, a source of alternating voltage for energizing said excitation circuit, phase shifting means interposed between said source and said excitation circuit for controlling the phase of the alternating voltage impressed on said control member, a high impedance reactive network for absorbing voltage transients of said source, a dynamo-electric machine of the induction type connected to be energized from said source through said network, and means comprising a transformer connected to be energized in accordance with the voltage appearing across terminals of said machine and points of said network for introducing into said excitation circuit an alternating voltage when said source fails temporarily.

9. In combination, an electric valve means having a control member, an excitation circuit for energizing said control member, a source of alternating voltage for energizing said excitation circuit, and energy storage means connected between said source and said excitation circuit for supplying a periodic control voltage to said control member during transient disturbances of said source, said periodic voltage being of substantially the same periodicity as said alternating voltage.

10. In combination, a polyphase alternating current circuit, a direct current circuit, a plurality of electric valve means connected between said circuits for transmitting energy therebetween and each comprising a control member for controlling the conductivity thereof, a plurality of excitation circuits each associated with a different one of said electric valve means for rendering said electric valve means conductive in a predetermined order, a source of polyphase alternating voltage for energizing said excitation circuits, and a polyphase dynamo-electric machine connected between said source and said excitation circuits, said machine being arranged to operate as a motor energized from said source during a normal operation of said source and being arranged to supply to said excitation circuits a balanced polyphase system of voltages in the event the voltages of said source deviate from a normal mode of variation.

11. In combination, a polyphase alternating current circuit, a load circuit, a plurality of electric valve means connected between said circuits for transmitting energy therebetween, said electric valve means each having a control member, a plurality of excitation circuits each associated with a different one of said electric valve means for rendering said electric valve means conductive in a predetermined order, a source of polyphase alternating voltage for energizing said excitation circuits, a polyphase dynamo-electric machine connected between said source and said excitation circuits and being arranged to operate as a motor during normal operation of said source and as a generator during transient disturbances of said source to supply to said excitation circuits a balanced polyphase system of voltages during the transient disturbance, and reactances connected in series relation with said source and said machine for limiting the energy transfer between said machine and said source during transient disturbances of said somce.

BURNICE D. BEDFORD.