US2357067A - Electric valve translating system - Google Patents

Description

1944- E. F. w. ALEXANDERS ON 2,357,067

ELECTRIC VALVE TRANSLATING SYSTEM Filed Aug. 29, 1941 2 Sheets-Sheet 1 Q Inv ehoor' Ernst, F. W. Alexander-son,

His Attorney.

1944- E. F. w. ALEXANDERSON 5 ELECTRIC VALVE TRANSLATING SYSTEM Filed Aug. 29, 1941 2 Sheets-Sheet 2 Fig.2. I

EVE/V A/VODE EVRRENTJ 4 VOLTS ANODE HMPS.

DEGREES RETARDED FIR/N6 NfflTRAL [ll/PRINTS (I) \1 s w a E 2 a g DEGREES RETARDED FIR/N5 Inventor: Ernst F. W. Alexander'son,

b ii zwyi zw/m Patented Aug. 29, 1944 2 ,357,067 morale v'anvn TRANSLATING srs'rnM Ernst F. W. Alexanderson, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application August 29, 1941, Serial No. 408,779 I, I l

9 Claims. (omits-s63) My invention relates to electric valve translating systems and more particularly to electric valve apparatus of the type employing an ionizable medium, such as a gas or a vapor, and which includes a control member for determining or controlling the amount of current transmitted to an associatedload circuit.

It has been found heretofore that it is highly desirable in electric valve translating apparatus to employ electric valve means of the type having a control member which determines or controls the amount of current transmitted to an associated load circuit. It has also been found inpractice that it is highly desirable to energize the control members by transmitting thereto impulses of voltage of peaked wave form because of the precision of control which may be obtained in rendering the electric valves conducting at predetermined instants dining the cycle of voltage of the associated supply circuit. Of course,

there have been developed from time to time improved circuits for producing voltages of peaked wave form, and concurrent with this development it has-become necessary to develop new and improved control circuits for adapting the excita- It is another object of my invention to provide new and improved .control circuits for electric valve translating apparatus.

It is a further object of my invention to provide a new and improved load balancing system for electric valve translating apparatus in which are preferably of the type employing an ionizable a plurality of groups of electric valves or electric discharge paths conduct current in parallel re-' lationship.

Briefly stated, in the illustrated embodiment of my invention I provide a new and improved load balancing system for electric valve translating apparatus wherein a plurality of groups of electric valves are connected in the system to operate in parallel. A plurality of excitation circuits are employed for producing voltages of peaked wave form and new and improved means are provided for assuring and maintaining equal division of load or current among the respective sr p For a better understanding" of my invention, 6

reference may be had to the following description taken in connection. with the accompanying drawings, audits scope is pointed out in the appended claims. P18. 1 atically illustrates an embodiment of my invention as applied 5 to a polyphase rectifying system, and Figs. 2 and 3 represent certain operating characteristics of electric translating apparatus; Fig. 2 represents the operation of the system without use of my improved control system; and Fig. 3 represents the operating characteristics when using my control system.

Referring to Fig. 1 of the drawings l have there illustrated my invention diagrammatically as applied to a polyphase rectifying system for energizing a load circuit including conductors i and 2 from a polyphase alternating current supply circuit 3. The electric valve translating system comprises a transformer 4 including a plurality of primary windings 5 and two groups 6 and I of electrically displaced or secondary phase windings. The two groups of secondary windings 6 and 'I include displaced windings 8-|3 having neutral connections N1 and N2, respectively, whichare connected gto, the negative conductor 1 of the direct current load circuit through an interphase transformer ll.

The electric translating apparatus also includes a plurality of electric valve means or electric discharge paths each connected to a different one of the phase windings 8-, inclusive. For the purpose of simplifying the presentation of my invention, I have shown only electric valve means I! and it connected to windings l2 and 9, respectively. It will be noted that electric valve means It and It are connected to phase windings displaced I electrical degrees. It will be appreciated that other electric valves are connected to the phase windings 8, II, II and It, although not shown. The electric valve means It and I6 medium, such as a gas or a vapor, and each includes an anode II, a cathode I. of the selfthe mercury and constructed of a material such as boron carbide or silicon carbide having an electrical resistivity relatively large compared.

with that of the associated mercury. If desired, the electric valve means It and It may also be provided with transfer or relieving electrodes 20 and an auxiliary control member or ballle 2|.

I employ a plurality of excitation circuits 2:, 23 and 24 of the nature disclosed and claimed in my copending Joint patent application Serial No.

'374,'l16, filed January 16, 1941, and which is assigned to the assignee of the present application. These excitation circuits are of the oscilla- 5 torytype which'produce-periodic or alternating voltages of peaked wave form and each comprises a transformer 25 having a primary winding 25 and a secondary winding 21. Each of the excitation circuits 22-24 also includes a saturable inductive reactance, such as a saturable inductive device 28 having a main winding 23 and a control winding 30. A capacitance 3| is charged from an associated source of alternating current, such as the supply circuit 3, through transformer 25 during a portion of the cycle of the voltage of the source and is discharged through the main winding 29 of theinductive reactance 28 when the inductive reactance of the winding 29 deenergizes substantially due to saturation of the associated magnetic core structure. The excitation circuits 22-24 also'include means such as an-auto-transformer 3| having a neutral connection 32. The capacitance 3| discharges through the transformer 3| and produces across the terminals of this transformer voltages of peaked wave form. The neutral connections 32 of the transformers 3| are connected to the cathodes l8 of the electric valve apparatus, and the terminals of the transformer 3| are connected to the control members |9 through unidirectional conducting devices 33 and 34 and through transfer resistances 35 and 35. The terminals of the transformer 3| are also connected to the relieving electrodes 20.

In series relation with the transformers 25 of excitation circuits 22-44, I employ phase shifting networks 31, 38 and 39, respectively. The phase shifting networks include a plurality of impedances connected to control the phase of the resultant voltages impressed on transformers 25 relative to the voltage of the respective associated phases of the polyphase supply circuit 3, and thereby control the phase relationship of the impulses of the voltages of peaked wave form produced by excitation circuits 22-24 and supplied to the control members IS. The phase shifting windings 31-39 may each comprise a variable impedance element such as a saturable inductive device 40 having a control winding 4| and impedances such as'a capacitance 42 and a resistance 43. I employ in each of the phase shifting networks 3135 damping means, such as a resistance 44, for controlling the oscillating action of excitation circuits 2224 so that the positive and negative impulses of peaked voltage produced by these excitation circuits are of substantially the same wave form.

The phase relationship of the voltages impressed across transformers 25 may be controlled by means of a circuit 45 which includes a current adjusting means, such as a rheostat 46 which transmits variable amounts of unidirectional current to the control windings 4|. Voltage limiting means, such as resistances 41, may be connected across the control windings 4|, if desired.

It will be noted that excitation circuit 22 transmits energizing impulses of current of peaked wave form to the control members I9 of electric valve means and I6 which are connected to phase windings 2 and 9, respectively, and which are displaced substantially 180 electrical degrees. 2:: like manner, the excitation circuit? re each connected to energize userfs of other pairs of electric vaive in as which are displaced by 180 electrical degrees.

I provide a control circuit 48 which controls excitation circuits 2322-44 to maintain a predetermined division of current or load among the groups 6 and l of phase windings and, conse- 76 quently, maintains an equal distribution of load current among the associated respective groups of electric valve means. The control circuit 43 includes polarity selective current responsive means, such as differentially connected current transformers 49 and 45', energized in response to the currents transmitted by electric valves I5 and II which are connected to different groups of phase windings. While the current transformers 45 and 45 are shown as being connected to be responsive to the anode currents oi electric valve means I5 and I6, it will be understood that these current responsive devices could be associated with other electric valves such as those associated with phase windings 5 and II. The excitation circuit 48 includes an impedance element, such as a resistance 50, which is energized in response to the difference in currents conducted by electric valve means l5 and 16. This selective energization of the resistance 53 may be obtained by employing a-pair of unidirectional conducting devices 5| and 52 which are poled to transmit current in opposite directions through resistance 50. In order to stabilize the voltage appearing across resistance 50 and to prevent over-shooting and under-shooting, current limiting reactances 53 and 54 may be connected in series relation with unidirectional conducting devices 5| and 52, respectively. A protective or voltage limiting means, such as a pair of resistances 55 and 58, may be connected in the circuit as shown and may be constructed of a material having a negative impedance-current characteristic such as that disclosed and claimed in United States Letters Patent No. 1,822,742 of Karl B. MacEachron, granted September 8, 1931 and which is assigned to the assignee of this application. I

The voltage appearing across the resistance 55 is employed to variably energize control windings 30 of saturable inductive devices 23 in excitation circuits 22-44 through a circuit 51 which may be connected to windings 30 through suitable switching means such as a. reversing switch 58. In order to prevent the transmission of alternating components of voltage appearing across the terminals of resistance 50 to control windings 30 and, therefore, to increase the sensitivity and precision of control, I provide suitable filtering means such as an inductance 59 which is connected in series relation with control windings 30.

The auxiliary electrodes 2| may be energized by impressing thereon alternating components of voltage by means of a transformer 60 having a plurality of primary windings 6| and plurality of secondary windings 62. The phase relationship of the alternating voltages impressed on electrodes 2| may be such as to assist in the transmission of the arc discharge from cathodes l8 to anodes l1 upon establishment of cathode spots by the proper energization of control members l9, and may be of that phase relationship which also assists in the deionization of the mercury vapor when the current is commutated from each electric valve-to the one succeeding it in the order of phase rotation.

The operation of the embodiment of my invention shown in Fig. 1 of the drawings will be explained by considering the system when it is operating to transmit uni-directional current to the load circuit including conductors and 2. As will be understood by those skilled in the art, the electric valves associated with phase windings 8-|3, respectively, conduct current in a predetermined order determined by the order of phase rotation of the voltages. In the particular arrangement shown, which is a double Y connection, due to the operation of the interphase transformer H, which equalizes the instantaneous voltages of electrically contiguous phases, the electric valve means conduct current in parallel, each electric valve conductin current for 120 electrical degrees but for only 60 electrical degrees with any one other electric valve in the other group. The magnitude of the current conducted by the various electric valve means and, hence, the voltage impressed across the load circuit is determined by the-time at which the electric valve means are rendered conducting during the positive half cycles of applied anode-cathode voltage. As the electric valve means are rendered conducting by the transmission of energizing current to control members It at earlier times during the positive half cycles, the voltage impressed across the load circuit is increased and as those times are retarded the voltage is decreased. Furthermore, a particular electric valve means and the valves associated with a particular group of phase windings may be made to transmit an increased amount of current by advancing the phase of the voltages electric valve means It relative to its associated phase winding 9. As a result, the system responds to restore the desired balance of current .between the two groups of windings. Conversely,

the system will'operate under the reverse condition where group I transmits a greater amount of current than group i, thereby restoring the ance. The operating characteristics shown in Figs. 2 and 3 may be referred to in order more fully to appreciate the manner in which systems built ofpeaked wave form and, conversely, may be made to conduct a decreased amount of current by retarding the phase of the peaked voltages.

The control circuit 48, which produces across the terminals of resistance 50 a voltage which is a function of the difference of the currents conducted by the respective groups of phase windings, variably energizes control windings ll of the saturable inductive devices 28. It willbe appreciated that by transmitting diflerent amounts of current to the control windings 30, the

phase relationship of the positive and'negative impulses of voltage relative to the voltage of cirwindings 30 and impressed on the core structure of these saturable) devices vary, the time at which the devices become saturated is also varied. In this manner, the time of occurrence of the voltages of peaked wave form is also varied. Furthermore, it is to be appreciated that as the unidirectional current transmitted to control windings 30 varies, the relative phase displacement between the positive and negative impulses of peaked wave form is changed. This displacement will become more pronounced, of course, as the polarity of the unidirectional voltage impressed acrqss control windings 30 by resistance 50 varies. Since excitation circuits 22-44 produce alternating voltages of peaked wave form having variable phase relationship between the positive and negative impulses, it will be understood that this change in phase displacement is employed to control the magnitude of the currents conducted by the respectivie groups Band 1 of phase windings. a

If it be assumed that one group of phase windings and associated electric valves, such as group cuit 3 is controlled due to the fact that as the g unidirectional magnetomotive forces produced by in accordance with my invention maintain an equal division of load among the respective phase winding groups. Fig. 2 indicates the uneven distributi'on of anode currents when control circuit 48 is not employed, and Fig. 3 represents the balance of anode currents-and neutral currents when control circuit. 48 is employed.

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: t

1. In combination, an alternating current supply circuit, a load circuit, electric translating apparatus connected between said circuits and comprising a plurality of groups of electrically displaced phase windings and a plurality of electric discharge paths each associated with a different one of said phase'windings and each including an anode and a control member, a plurality of excitation circuits connected to said control members for transmitting thereto periodic voltages of peaked wave form, and means for controlling the division of load between the groups of phase windings and comprising a pair of differentially connected current responsive means one of which is responsive to the current con- 6 and the electric valve I5. transmits a greater amount of current than group 1 and its associated electric valve apparatus, the rectifier 5| transmits a greater amount of current to resistance 50 and hence the upper terminal of the resistance 50 becomes positive in potential with respect to the lower terminal, causing the trans mission of current in one direction to control windings 30 of the saturable inductive devices 28.

Transformers 9 and 49' are arranged so that ducted by one phase winding of one group and the other of which is responsive to the current conducted by one phase winding of another group, an impedance element, means comprising a pair of unidirectional conducting devices responsive to the current of said current responsive means andconnected to transmit current in opposite directions through said impedance element and means for controlling said excitation circuits in response to the voltage across said impedance element.

. 2. In combination, a polypliase alternating current supply circuit, a load circuit, electric translating apparatus connected between said circuits and comprising a plurality of groups of electrically displaced phase windings and a pair. of electric discharge paths each associated with a different one of said windings and each including a control member for controlling the current conducted thereby, a plurality of excitation circuits for impressing on said control members periodic voltages of peaked wave form and comprising variable impedance elements for controlappearing across said impedance element is a function of the difference in the currents conducted by said groups, and means for controlling said variable impedance elements in response to the voltage appearing across said impedance element.

3. In combination, an alternating current supply circuit, a load circuit, electric translating apparatus connected between said circuits and comprising a plurality of groups of electrically dis-- placed phase windings and a plurality of electric discharge paths each associated with a different 7 one of said phase windings and each including a control member for controlling the current conducted thereby, a plurality of excitation circuits for impressing on said control members periodic voltages of peaked wave form and including saturable inductive devices having control windings, said excitation circuits serving to control the relative phase displacement between'the voltages impressed on the control members of the discharge paths in the respective groups of phase windings, means responsive to the current conducted by the respective groups of phase windings and each including current responsive means, an impedance element, means comprising a pair of unidirectional conducting devices energized by the current responsive means for conducting current through said impedance element in opposite directions so that the voltage appearing across said impedance element is a function of the difference in the currents conducted by said groups, and means for controlling the energiza tion of said control windings in response to the voltage appearing across said impedance element.

4. In combination, a polyphase alternating current circuit, a load circuit, electric translating apparatus connected across said circuits and comprising two groups of electrically displaced phase windings and a pair of electric discharge paths each associated with a different one of said windings and each having a control member for controlling the current conducted thereby, the groups of phase windings being arranged to provide voltages displaced 180 electrical degrees with respect to the phase voltages of the other group, a plurality of excitation circuits for impressing periodic voltages of peaked wave form on the control members and each including a saturable inductive device for controlling the relative phase displacement between the voltages impressed on the control members in the respective groups,

lating apparatus connected between said circuits and comprising two groups of phase windings and two groups oi. electric discharge paths each having a control member for controlling the current conducted thereby, said groups of phase windings being arranged to conduct current in parallel to said load circuit, an excitation circuit connected to the control members of two electric discharge paths one of which is connected in one group of said phase windings and the other of which is connected in the other group of said phase windings and comprising a saturable inductive device for producing an alternating voltage of peaked wave form, said saturable inductive device including a control winding for controlling the phase displacement between the positive and negative impulses of peaked voltage, and polarity selective means responsive to the diilerence oi the currents conducted by said two electric discharge paths for variably energizing said control winding.

6. In combination, a polyphase alternating current supply circuit, a load circuit, electric translating apparatus connected between said circuits and comprising two groups of phase windings and two groups of electric discharge paths each having a control member for controlling the current conducted thereby, said groups of phase windings being arranged to conduct current in parallel to said load circuit, an excitation circuit connected to the control members of two electric discharge paths one of which is connected in one group of said phase windings and the other of which is connected in the other group of phase windings and comprising a saturable inductive device for producing an alternating voltage of peaked wave form, said saturable inductive device including a control winding for controlling the phase displacement between the positive and negative impulses of peaked voltage, and polarity selective means for variably energizing said control winding in response to the difference in the electric currents conducted by said electric discharge paths in ditierent groups.

'7. In combination, a polyphase alternating current supply circuit, a load circuit, electric translating apparatus connected between said circuits means responsive to the current conducted by the respective groups of phase windings and each including a current responsive means, a resistance, means comprising a pair of unidirectional conducting devices for conducting current to said resistance in opposite directions so that the voltage appearing across said resistance is a function of the difierence in the currents conducted by said groups, and means for controlling said saturable inductive devices in response to the voltage appearing across said resistance.

5. In combination, a polyphase alternating ourrent supply circuit, a load circuit, electric trans- 7 and comprising two groups of phase windings and two groups of electric discharge paths each having a control member for controlling the current conducted thereby, said groups or phase windings being arranged to conduct current in parallel to said load circuit, an excitation circuit connected to the control members of two electric discharge paths one of which is connected in one group of said phase windings and the other of which is connected in the other group of said phase windings and comprising a saturable inductive device for producing an alternating voltage of peaked wave form, said saturable induc.. tive device including a control winding for controlling the phase displacement between the positive and negative impulses or peaked voltage, a pair of polarity selective current responsive means one associated with an electric discharge path in one group and the other associated with an electric discharge path in the other group 01' phase windings, a resistance, means energized by the current responsiv means for energizing the resistance in response to the difference in currents conducted by the last mentioned electric discharge paths, and means for connecting said control winding across said resistance.

8. In combination, a polyphase alternating current supply circuit, aload circuit, electric translating apparatus connected between said circuits and comprising two groups of phase windings and two groups oi electric discharge paths each having a control member for controlling the current conducted thereby, said groups oi phase windings being arranged to conduct current in parallel to said load circuits, an excitation circuit connected to-the control members of two electric discharge paths oneof which is connected in one group of said phase windings and the other of which is connected in the other group of said phase windings and comprising a saturable inductive device for producing an alternating voltage of peaked wave form, said saturable inductive device including a control winding for controlling the phase displacement between the positive and negative impulses oi peaked voltage, a pair of polarity selective current responsive means one associated with an electric discharge path in one group and the rent supply circuit, a load circuit, electric trans lating apparatus connected between said circuits and comprising two groups of phase windings and two groups of electric discharge paths each having a control member for controlling the current conducted thereby, said groups of phase windings being arranged to conduct current in parallel to said load circuit, an excitation circuit other associated with an electric discharge path in the other group of phase windings, a resistance, means energized by the current responsive means for energizing the resistance in response to the diflerence in currents conducted by the last mentioned electric discharg paths, and means for connecting said control winding across said resistance and comprising filtering means for preventing the transmission oi. alternating components of current to said control winding.

9. In combination, a polyphase alternating ourconnected to the control members of two electric discharge paths one of which is connected in one group of said phase windings and the other of which is connected in the other group of said phase windings and comprising a saturable inductive device for producing an alternating voltage of peaked wave form, said saturable inductive device including a control winding for controlling the phase displacement between the positive and negative impulse of peaked voltage, a pair of polarity selective current responsive means associated with electric discharge paths in difierent groups, a resistance, a pair of unidirec: tional conducting devices connected between said current responsive means and said resistance for energizing said resistance in response to the difference in currents conducted by the last mentioned discharge paths, and filtering means connected between said resistance and said control winding to prevent the transmission of alternating components of current to said control winding ERNST F. W. ALEXANDERSON.

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