US2300269A - System for electric valve translating apparatus - Google Patents

Description

Oct. 27, 1942. Y. TODA 2,300,269

v SYSTEM FOR ELECTRLC VALVE TRANSLATING APPARATUS Filed May 24, 1940 Inventof Yoshiaki Toda,

' 6 AM by l mtorhey Patented Oct. 27, 1942 SYSTEM FOR ELECTRIC VALVE TRANSLAT- ING APPARATUS Yoshiaki Toda, Tokyo, Japan, assignor to General Electric Company, a corporation of New York Application May 24, 1940, Serial No. 336,995 In Japan September 27, 1939 9 Claims.

My invention relates to electric valve translating apparatus and more particularly to a protective or control system for electric valve apparatus of the type employing an ionizable medium, such as a gas or a vapor.

It is frequently desirable in the control of electric valve translating apparatus to provide means for reducing the current conducted by the electric valve means in the event of an abnormal operating condition such as arc-back. In accordance with the teachings of my invention described hereinafter, I provide a new and improved control system for electric valves utilizing apparatus for suppressing the current conducted during an arc-back condition and for restoring the rectifiers to normal operation.

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

It is another object of my invention to provide a new and improved control and protective system. for electric valve translating apparatus.

It is a further object of my invention to provide a new and improved arc-back suppression system for electric valve rectifiers wherein the electric valves are rendered non-conductive upon the occurrence of an arc-back and wherein the electric valves are gradually restored to the normal operating condition.

Briefly stated, in the illustrated embodiment of my invention I provide an improved system for reducing the current conducted by electric valve means upon the occurrence of an irregular or abnormal operating condition, such as arcback. Upon the occurrence of an overload condition or upon the occurrence of an arc-back, the normal grid excitation for the electric valve means is removed and the negative voltage is impressed on the grids to supp the arc and reduce the current conducted by the electric valve means. The grid excitation is automatically re-applied but is modified in a manner to effeet a gradual increase of the current conducted by the electric valve means, thereby restoring the system to its normal operation.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. The single figure of the accompanying drawing diagrammatically illustrates an embodiment of my invention as applied to a three phase rectifier.

Referring now to the single figure of the drawing, my invention is there illustrated as applied to an electric valve rectifying system for energizing a direct current load circuit I from a polyphase alternating current supply circuit 2 through electric translating apparatus comprising a transformer 3 having primary windings 4 and secondary windings 5, and includes an electric valve means 6 preferably of the type employing an ionizable medium such as a gas or a vapor and having an anode l, a cathode 8 and at least one control member or grid 9. It will be understood, of course, that the electric valve means may be of the type employing a plurality of anodes I each having an associated control grid 9 and utilizing a single associated cathode such as that shown.

I provide an excitation circuit ID for impressing on the control grids 9 periodic voltages to render the associated arc discharge paths of the electric valve means 6 conductive in a predetermined order or sequence. The excitation circuit l0 may comprise a transformer ll having primary windings l2 and secondary windings I3 and includes a suitable phase shifting device, such as a rotary phase shifter I4, preferably having a distributed stator winding I 5 and a secondary winding l6 mounted upon a rotatable structure to produce the desired shift or change in phase of the voltages impressed on the control grids 9 relative to the respective anode-cathode voltages. The rotary phase shifter I4 is also provided with a member I! which rotates in accordance with the angular position of the rotatable structure of the phase shifter and includes stop members I8 and I9 which engage the member I! when the rotating structure of the phase shifting structure assumes certain limiting positions. For example, the stop It! establishes the full-on or maximum output voltage of the electric valve means 6 and the stop I!) establishes the point or position of zero output voltage or zero power output of the electric valve means '6. The output or secondary voltages of the rotary phase shifter I4 are preferably converted into alternating or periodic voltages of peaked wave form by suitable apparatus, such as a saturable peaking transformer 20 comprising primary windings 2| and a plurality of secondary windings 22 having an electrical neutral connection 23. To provide a suitable source of negative unidirectional biasing potential sufficient in itself, when acting alone, to suppress the arc discharge of the electric valve means 6 under arc-back conditions, I employ a suitable means such as a battery 24, which may be connected between the cathode 8 and the neutral connection 23 of secondary windings 22. Of course, the voltage furnished by battery 24 cooperates with the voltages of peaked wave form produced by secondary windings 22 of transformer to render the arc discharge paths of the electric valve means 6 conductive in a predetermined order. The phase position of the voltages of peaked wave form are controlled by the angular position of the rotating member of the rotary phase shifting device l4.

The excitation circuit III also includes switching means, such as a pair of switching means 25 and 26, which control the energization of the rotary phase shifting device l4. The switching means 25 includes a suitable actuating means, such as a closing and holding coil 21, holding contacts 28 and means, such as auxiliary contacts 29, for initiating the energization of the closing and holding coil 30 of the switching means 26. The switching means 25 is also provided with a suitable pair of contacts 3| which are effective to control the energization of the positioning means for the rotary phase shifting device M. This positioning means is described in detail hereinafter. The switching means 25 is biased by a suitable means, such as a spring 32, to be moved to the open circuit position upon the deenergization of the closing coil or holding coil 21.

Switching means 26 is also provided with a set of auxiliary contacts 33 which complete a circuit for the energization of the closing coil 21 of the switching means 25 when the switching means 26 is in the open circuit position, thereby providing a circuit for initiating the closure of switch 25 when switch 26 is in the open circuit 1 position. Switching means 26 is also provided with a further set of auxiliary contacts 34 which operate to control the positioning means described hereinafter. Closing coils 21 and 3|] of switching means 25 and 26, respectively, may be energized from a suitable source of current, such as a, direct current circuit 35, and a control switch 36 may be connected in series relation with contacts 33 to initiate or discontinue operation of the system.

Switching means 26 is connected between the secondary windings |3 of transformer I I and the stator winding |5 of rotary phase shifting device H in a manner to change the phase rotation of the output voltage of the phase shifting device l4. In this manner, when switching means 26 is closed, upon the occurrence of an abnormal condition, the output voltage of the phase shifting device l4 may be arranged to impress an instantaneously negative voltage on certain grids of electric valve means 6. In this manner, the alternating voltages of the phase shifter M are additionally shifted in phase during the protective operation.

As an agency for effecting selective operation of switching means 25 and 26 in response to the angular position of the rotary phase shifter 4, I provide a suitable controlling means 31. Controlling means 31 may be mechanically coupled to the rotating structure of the phase shifting device l4 and may comprise a drum contactor 38 having stationary contacts 39 and 40 and associated movable contacts 4| and 42, respectively. Contact 4| is dimensioned so that it engages contacts 39 only when the rotary phase shifting device 36 is in that position corresponding to zero output voltage or reduced power output of the electric valve means 6, that is, contact 4| engages contacts 39 only when the member engages stop I9. The contact 42 is furthermore proportioned so that it engages or completes the circuit through contacts 40 at all times excepting when the member engages contacts 19. In this manner, the closing coil or the holding coil 30 of switching means 26 is energized when the switching means 25 is in the open circuit position so long as the rotary phase shifter I4 is not moved to the extreme retarded position where the member engages stop l9. When that position is reached, the energizing coil for coil 30 is open and the circuit for energizing coil 21 is completed through a circuit including contacts 39 and 4|.

I provide a positioning means 43 for controlling the position of the rotary phase shifter l4 and hence the phase of the voltages impressed on the grids 9. This positioning means may comprise a suitable motor, such as a direct current motor 44, having an armature 45 and a pair of field windings 46 and 41 which are selectively energized to control the direction of rotation of the armature 45. I also provide a pair of adjustable resistances 48 and 49 which determine and permit independent adjustment of the rates of forward and reverse rotation of the armature 45 and hence permit independent adjustment of the rate of advancement and retardation of the periodic voltages impressed on the grids 9. The circuits for field windings 46 and 41 are energized from the direct current circuit 35.

I provide a suitable means, such as an overload relay 50, responsive to a predetermined operating condition such as an abnormal operating condition of the electric translating circuit to initiate the operation of the protective system. The relay 56 may comprise an actuating coil 5| energized in response to the anode-cathode current of the electric valve means 6. A suitable current transformer 52 may be employed for this purpose. Relay 56 also comprises a pair of contacts 53 which shunt the closing coil 21 of switching means 25 and hence initiate the operation of the system. Relay 56 also includes contacts 54 which serve to complete a circuit for the proper control of the positioning means 43 upon the occurrence of the abnormal condition.

Resistance 34 is connected in circuit with the contacts 54 of relay 5!) and is an element in the circuit which energizes field coil 41 of motor 44 when auxiliary contacts 34 of switching means 26 are closed. Resistance 34 is also connected to the neutral connection 23 of secondary windings 22 to provide an additional negative biasing voltage when contacts 54 of relay 5!] and contacts 34 of switching means 26 are closed.

The operation of the embodiment of my invention shown in the single figure of the drawing will be explained by considering the system when it is operating as a rectifier to transmit unidirectional current to the load circuit I from supply circuit 2. The three are paths of the electric valve means 6, of course, conduct current in order, each anode transmitting the load current for electrical degrees during each cycle of voltage of circuit 2. The magnitude of the voltage impressed on the direct current circuit is, of course, determined by the phase relation between the voltages impressed on the grids 9 and the anode-cathode voltages. The load voltage is maximum as the grid voltages are brought more nearly into phase coincidence with the anode-cathode voltages and, conversely, the load decreases as the grid voltages are retarded in phase. The periodic voltages of peaked wave form produced by the peaking transformer 50,

under normal conditions, are of suflicient magnitude to overcome the effect of the negative biasing voltage produced by battery 24. The system operates to suppress arc-backs upon the occurrence thereof and also operates to reduce the load transmitted by the electric valve means 6 and to effect a gradual re-application of load thereto.

During normal operating conditions, the phase shifting device I4 is energized through transformer H, the switching means 25 being maintained in the closed circuit position by the energization of the closing coil 21 through a circuit including the positive terminal of circuit 35, coil 21, holding contacts 28, contacts 33 of switching means 26, switch 36, and the negative terminal of the circuit 35. Of course, by opening switch 36 this circuit may be interrupted to deenergize coil 21 and permit'the movement of switching means 25 to the open circuit position thereby rendering valve means 6 non-conducting. In like manner, by closing switch 36 the system may be placed in operation.

If it be assumed that the system is subjected to an abnormal operating condition, such as an arc-back, the increase in current in the associated alternating circuit will effect operation of relay 50. Upon operation of relay 50, contacts 53 are closed, thereby shunting holding or closing coil 21 of switching means 25 and effecting deenergization thereof and permitting movement of the switching means 25 to the open circuit position, removing for a predetermined time the energizing voltage for the excitation circuit I8. Upon removal of the periodic voltage of peaked wave form from the grids 9, the negative biasing potential furnished by battery 24 is suflicient to suppress the are within electric valve means 8 and thereby render the electric valve means nonconductive and consequently correct the disturbance.

After switching means 25 is permitted to move to the open circuit position, closing and holding coil 3|] of switching means 26 is energized through a circuit including the positive terminal of circuit 35, coil 30, contacts 40 and 42 of the drum 38, contacts 29 which are closed since switching means 25 is in the open circuit position, and the negative terminal of circuit 35. Upon the energization of coil 30, switching means 26 is moved to the closed circuit position. Upon closure of switching means 26, auxiliary contacts 34 are also closed effecting energization of the positioning means 43 in a manner to retard the rotary phase shifter M to a position corresponding to the zero voltage position, that is, to that position where member I! engages stop l9. Field winding 41 of motor 44 is energized to retard phase shifting device |4 through the following circuit: the positive terminal of circuit 35, contacts 54 of relay resistance 34', auxiliary contacts 34 of switching means 26, resistance 49, winding 41 and the negative terminal of circuit 35. This position of the rotary phase shifting device l4 corresponds to zero voltage output of the electric valve means 6. During the time when contacts 54 of relay 50 are closed and contacts 34 of switching means 26 are closed, an additional negative bias voltage is impressed on grids 9 by means of resistance 34'. This bias voltage is produced so long as contacts 54 and 34 are closed. Resistance 34 is energized through a circuit including the positive terminal of source 35, contacts 54 of relay 50, resistance 34', contacts 34, resistance 49, field winding 41,

and the negative terminal of source 35. As soon as either contacts 54 or 34 open, the bias voltage produced by resistance 34 disappears. Of course, it is desirable to provide this additional bias voltage during the operation in which phase shifter 4 is retarded. After switching means 26 opens, phase shifter I4 is slowly advanced and it is desirable toremove thebias voltage so that the current conducted by electric valve means 6 may be gradually increased. At this position of the rotary'phase shifter I4, the contacts 40 and 42 of the drum contactor 38 are not in engagement and contacts 39 and 4| are engaged. Contacts 40 and 42 in the open circuit position deenergize the holding and closing coil 38 of switching means 26, permitting movement of this switching means to the open circuit position. Closure of contacts 39 and 4| effects energization of the closing coil 21 of switching means 25, moving switching means 25 to the closed circuit position. The circuit for energization of closing coil 21 at this stage in the operation of the system includes the positive terminal of circuit 35, contacts 39 and 4|, contacts 33, switch 36 and the negative terminal of circuit 35. Accordingly, the phase shifting device [4 is rotated by means of motor 44 to advance gradually the phase of the periodic voltages impressed on grids 9 from the zero voltage position to the normal or full voltage position. The rate at which the periodic voltages are advanced in phase is determiend, of course, by the adjustment of resistance 48. The circuit for effecting energization of the motor 44 to advance the phase of the periodic voltages is as follows: the positive terminal of circuit 35, contacts 3| of switching means 25, resistance 48, field winding 34, and the negative terminal of circuit 35. The phase shifting device I4 is advanced gradually until the member engages stop I8, at which time the output voltage of the electric valve means 6 has been increased to its nominal or rated value. The system is then reset to the initial condition to permit reduction of loadand arc suppression in the event of another arc-back condition.

.From the above-described operation of the system, it will be understood that negative voltages are impressed on the grids 9 almost instantaneously upon the occurrence of an arcback condition, and that the load is applied gradually to the electric valve means 6. Furthermore, the movable member of the rotary phase shifting device I4 is retarded very rapidly as compared with the rate of advancement. This selective adjustment or control of the relative rates of retardation and advancement is obtainable by means of resistances 49 and 4B, respectively. The motor 44 is made to retard the rotary phase shifting device |4 Very rapidly and is controlled to advance the device l4 slowly.

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, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising electric valve means having at'least one control member for controlling the current conducted thereby, an excitation circuit comprising phase shifting means for impressing on said control member a periodic voltage variable in phase relative to the voltage of said alternating current circuit, a source of negative unidirectional biasing potential sufficient to render said electric valve means non-conductive, means responsive to a predetermined electrical condition of one of the first mentioned circuits for removing said periodic voltage thereby permitting said biasing potential to render said electric valve means non-conductive, control means for said phase shifting means for retarding and advanc ing the phase of said periodic voltage, and electrical means for independently adjusting the relative rates of retardation and advancement of said periodic voltage.

2. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising electric valve means having at least one control member for controlling the current conducted thereby, an excitation circuit comprising phase shifting means for impressing a periodic voltage on said control member, positioning means for said phase shifting means, means for impressing a biasing potential on said grid, means for removing said periodic voltage from said control member so that said biasing potential renders said electric valve means non-conducting, means for energizing said positioning means to retard in phase said periodic voltage while it is ineffective to control said electric valve means and for subsequently applying said periodic voltage to said control member and for advancing the phase of said periodic voltage relative to the voltage of said alternating current circuit, and electrical means for independently adjusting the relative rates of retardation and advancement of said periodic voltage.-

3. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising electric valve means having at least one control member for controlling the current conducted thereby, a source of negative unidirectional biasing potential suflicient in itself to render said electric valve means non-conductive, means responsive to an operating condition of said electric valve means for controlling the phase of said periodic voltage to permit said negative biasing potential to render said electric valve means non-conductive, and means for controlling said periodic voltage to increase gradually the current conducted by said electric valve means.

4. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising electric valve means having at least one control member for controlling the current conducted thereby, an excitation circuit for impressing a periodic control voltage on said control member and comprising switching means for connecting said excitation circuit to said alternating current circuit and including a rotary phase shifting device for controlling the phase of said periodic voltage, positioning means for operating said rotary phase shifting device, and means responsive to a predetermined operating condition of said electric valve means for moving said switching means to the open circuit position, energizing said positioning means to decrease the current conducted by said electric valve means and for subsequently closing said switching means and operating said positioning means to increase gradually the current conducted by said electric valve means.

5. In combination, an alternating current circuit, a load circuit, electric valve translating apparatus connected between said circuits for transmitting power therebetween and comprising at least one control member for controlling the current conducted thereby, an excitation circuit energized from said alternating current circuit and comprising a rotary phase shifter for impressing on said control member a periodic voltage, a source of negative biasing potential and positioning means for said phase shifter to control the phase of said periodic voltage, a pair of switching means interposed between said excitation circuit and said alternating current circuit, interlocking means connected between said pair of switching means to prevent simultaneous closure of said switching means, means responsive to a predetermined electrical condition of said translating apparatus for opening one of said switching means, means for energizing said positioning means to retard said rotary phase shifting device, and means responsive to the operation of said pair of switching devices for operating said rotary phase shifting device to advance the phase of said periodic voltage.

6. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising an electric valve means having at least one control member for controlling the current conducted thereby, a source of negative unidirectional biasing potential, an excitation circuit for impressing a periodic voltage on said control member sufficient in magnitude to overcome the effect of said biasing potential and including a rotary phase shifting device for controlling the phase of said periodic voltage, positioning means for operating said rotary phase shifting device, means responsive to a predetermined operating condition of said electric valve means for moving said switching means to the open circuit position thereby removing said periodic voltage from said control member and rendering effective said negative unidirectional biasing potential to interrupt the current transmitted by said electric valve means, and means for subsequently closing said switching means and operating said positioning means to increase gradually the current conducted by said electric valve means.

7. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising electric valve means having at least one control member for controlling the current conducted thereby, a source of negative unidirectional biasing potential sufficient in itself to render said electric valve means non-conductive, an excitation circuit for impressing a periodic control voltage on said control member and of a magnitude suflicient to overcome the effect of said biasing potential, a pair of switching means for connecting said excitation circuit to said alternating current circuit and including a rotary phase shifting device for controlling the phase of said periodic voltage, actuating means for said pair of switching means, interlocking means con.- nected between said pair of switching means for effecting closure of one of said switching means upon the opening of the other switching means, positioning means for said rotary phase shifting device, means responsive to a predetermined operating condition of said electric valve means for energizing the positioning means for said phase shifting device to open one of said switching means and retard the phase of said periodic voltage, and means responsive to said one switching means to close the other switching means and to open subsequently said other switching means and to close said one switching means and lastly effecting a gradual advancement in the phase of said periodic voltage.

8. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising electric valve means having at least one control member for controlling the current conducted thereby, a source of polyphase alternating current, an excitation circuit comprising phase shifting means for impressing on said control member a periodic voltage variable in phase relative to the voltage of said alternating current circuit, said phase shifting means being of the rotary type having a polyphase stator winding and a polyphase output winding, switching means for connecting said source to said stator winding to produce the same direction of phase rotation of the output voltages of said stator winding as the phase rotation of said alternating current circuit, a second switching means for connecting said source to said stator Winding to produce a different order of phase rotation of the voltages of the output winding relative to the voltages of said alternating current circuit, means for controlling the first mentioned switching means to maintain that switching means closed during normal operation of said electric valve means, and means responsive to a predetermined operating condition of said electric valve means to open the first mentioned switching means and to close said second switching means for a predetermined interval of time.

9. In combination, a polyphase alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising electric valve means having a plurality of anodes and a plurality of associated control members for controlling the current conducted thereby, a source of negative unidirectional biasing potential suificient in itself to render said electric Valve means non-conductive, a

source of polyphase alternating current, an eXcitation circuit including a polyphase rotary phase shifting device for impressing on said control members periodic voltages adjustable in phase with respect to the voltages of said alternating current circuit, switching means connected between said source and said phase shifting device so that said phase shifting device supplies to said control members voltages having the same order of phase rotation as the voltages of said alternating current circuit, a second switching means for energizing said phase shifting device from said source in a manner so that said phase shifting device supplies voltages having a diiferent order of phase rotation relative to the Voltage of said alternating current circuit, means for maintaining the first mentioned switching means in the closed circuit position during normal operation, means for maintaining said second switching means in the open circuit position during normal operation. means responsive to a predetermined electrical condition for opening the first mentioned switching means and thereby permitting said negative biasing potential to render said electric valve means non-conductive, means for closing said second switching means and for retarding said rotary phase shifting device, means for opening said second switching means and closing the first mentioned switching means, and means for advancing gradually said rotary phase shifting device to increase gradually the current conducted by said electric valve means.

YOSHIAKI TODA.

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