US2047760A - Electric valve control system - Google Patents

Description

July 14, 1936. H. WlNOGRAD ELECTRIC VALVE CONTROL SYSTEM Filed July 26, 1954 2 heets-Sheet 1 Ju ly 14, 1936.

H. WINOGRAD ELECTRIC VALVE CONTROL SYSTEM Filed July 26, 1954 2 Sheets-Sheet 2 6A TIIRA 7'50 Patented July 14, 1936 ,1 'T* D 121w oFFicE; ao rmct ELEcirnI c-vALvE CONTROL SYSTEM mam c aret; Milwaukee: assignori to 'Alli sgfihalrners' Manufact i i: C pan 'Mil'- wauke'e; Wis:,' corporatio ii of -1) 1aware- A piimibn J uly gag-1934;seams.- 736,978

Claims-LS(GEN 363)? This-invention relates infgeneral to improvements in: electric valve control, systems, and more particularly to circuits" for energizing con trol electrodesof a-valve-for'controlling the oper ationthereof. V t i l Electric valves or the vapor type arefrequently: associated with alternatingcurrent windings to, constitute alternating current rectifying, direct current inverting, frequency changing and other, currenttranslating systems. Insuch systems; it is generally advantageous or even necessary to energize the control electrodes f the "valve with periodic potentials, each control: electrode being brought toa negative potential'to prevent 'or delay the flow of current through the. associated anode 'until the proper time in the voltage cycle of the winding associated withthewvalve, and being brought-to a positive potential with'respect to the cathode torelease such flow of current; To cause interruption ofthe flow ofxcurrent through" the valve it is generally; preferred :to utilize the action of the control electrodes which,- upon being brought to a negativepotential with respect to the cathode, will prevent further'sequential establishment of the flow of current through the anodes of the valve. l a r.

" Between operating periods of eachano'd'e in the'course of normal operation of the va1ve,'an'd' also at'times-of negative energization ofthe control electrode for causinginterruption of theflow ofcurrent through the" va1ve,' each control-elemtrode may' accomplish its purpose of preventing the establishment of fiow of current through-the associated anode only after first collecting the charges of positive ions presentpin'the spac'e the'reabout,-such collection-j causingthe flow of current from the control electrode to 'theene'r gizingcircuit therefor; -Such"current isof lim ited intensity and should encounter onlycorn parativelylow impedance to' permit the'most emcient action of the control "electrode. In the contra'ry' condition; when a control; electrode is at' a positive" potential, the-current now from the en-f ergizing circuit to the control electrode is limited" only by the impedance or the circuitg and such impedance should be maintainedat ahigh value to reduce a the system losses of such current. I M v It is therefore oneof the objects of thepresent invention to provide a control system f or' a'n electricvalve in which the mpedance of a control electrode-circuit is of different valuesfor metwc directionsof flow of curr entth erethrough.

Another object of the'pre'sent invention "is to provide a'con'trofsyst'e'm for an electric valve "in caused" by" the How which each control electrode circuit includes an impedance which is'bridged by an'electric'valve.

Another object of the present invention is to provide a controlsystemfor an'electricuvalve by means of which the space about each control electrode is rapidly deionized upon negative energization of the'controlelectrode. v

Another" object of the presentinvention is to provide a control system for anelectric'valve in whichith'eg applicationnof negative potential" to 10 i the control electrodet'fromavoltage source is accelerated to the greatest po'ssibleextenti Objects andadvantagesother than those above setforth will be apparent from the following de-' scription when read in connection withthe'accompanying drawings'pin which: v

Figure l diagrammatically illustrates oneem bodirnent of the present invention applied" to the'co'ntrol of an electric valve controllingthe fioWIofenergy between a directcurrentlineand 2 an alternating current line; and l Figure 2 diagrammatically illustrates a portion ofa: modified embodiment'of the present inven-' tion differing: from the embodimentillustrated in Figure-1 in theuse of asingle auxiliary ele'c'- tric'valve,"rather' than a plurality of such valves for controlling the flow of current through a plurality of control electrode circuits; Referring more particularly to the drawing by characters "o f 'referen'ce, reference numeral 6"gn-"' 3.0" erally designates anelectric valve of the distal: tinu'ou'sly controllable type utilized roe control} ling the" new of currentbetween an alternating current line! and a'dire'ct' current line 81: The anodes 9 of valve 6 are severally connected'with the phase displaced portions of one winding {I l of a transformer [2' having another winding" l3 thereof connected with line I. Winding"|l may be connected with one of thefconductorsof line 8 "either directly or through an interpha'se transformfer M as is well known'in the" art, Valve 6 is als'dprovide'd w'ith a'catho'del 6 connected wan the other conductor oflin'e 8'. Thefpote'ntial of cathode lfi will herein be used as "datum for po-' tentials and allpotentialswill' be referred' threto; a source ofvoltage connecting an'elementof the alve: with" the cathode" then impressing on such elern'enta potential component'equal to' the voltage of such source. Valve 6 is also provided with the usual means for bringing. and 'maintaihing" part or all of cathode l 6 a at incandescen'c'e; sucnmeansbeing well known in the art and therefore notsh'own.

The 'fi'owj of current through "valve 6"is' controlled by suitable discharge controllin'g' 'm'eans" such as control electrodes I! each connected with cathode I6 by means of a control electrode circuit including one or more sources of control voltage. In the description of the present embodiment it will be assumed that direct current obtained from line 8 is to be converted into alternating current to be supplied to line 'I. As is well known, each control electrode I! may then be at a positive potential only during a portion of the voltage cycle which is, at the most, notmaterially longer than the operating period of the associated anode. To obtain such control electrode energization, each control electrode may be comiected with one of the phase displaced portions of the secondary winding I8 of a transformer I9 having a primary winding 2| energized from line 7. The core 22 of transformer I9 and the winding 2| are preferably so dimensioned that the core is highly saturated when the voltage of line I is at the normal value thereof, with the result that the voltage of each portion of winding I8 presents sharp peaks instead of being sinusoidal. The neutral point of winding I8 is preferably connected with cathode I6 through a source of unidirectional voltage such as .avoltage divider 23 connected across a suitable source of direct current voltage suchas a battery 24. The connection of winding I8 with voltage divider 23 is such as to'cause the impression on each control electrode of a negative unidirectional voltage component of a magnitude somewhat less than the peak value of thevoltage of winding I8, so that each control electrode becomes positive only during the peak of the voltagewave of winding I8 and is at. a negative potential during the remainder of the voltage cycle.

Each control electrode circuit includes suitable impedance means such as a resistor 26 of comparatively high value and another resistor 21 of comparatively low value. Each resistor 26 is bridged by an electric valve'28 of any suitable type which is so connected as to conduct current flowing from control electrodes I! to the associated circuit I5. The moment of the voltage cycle at which the control electrode is brought to a positive potential may be varied by shifting the phase of the voltages of transformer I9 by means of a phase shifter 29 inserted in the connection between line I and winding 2|. For the purpose of causing interruption of the flow of current through valve 6 upon occurrence of a disturbance in the system, the system is provided with means responsive to the occurrence of such disturbances such as relays 3| and 32 having the coils thereof energized from a current transformer 33 inserted in the connection between winding I3 and line I. Relay 3I normally completes the connection between the neutral point of winding I8 and voltage divider 23 and, upon operation thereof, connects the neutral point of winding I8 with the negative terminal of battery 24. Operation of relay 32 causes short circuiting of phase shifter 29 or of winding 2| to substantially suppress the alternating voltage component impressed on control electrodes H, the flow of current through the contacts of relay 32 being limited by suitable impedance means such as resistors 34.

In operation, the system being connected as shown in the drawings, each control electrode receives a peaked alternating voltage component from one of the portions of winding I8, such component being superposed on a negative voltage component received from voltage divider 23.

Each control electrode is thus maintained at a negative potential during the greater part of the voltage cycle of line I and becomes positive once per cycle for a short time interval. The phase relation between the associated portions of windings II and I8 is so adjusted that when a control electrode I'I becomes positive, the associated anode 9 is receiving an increasing negative voltage from the associated portion of winding II, such voltage being however smaller in magnitude than 1 the voltage then received by the anode at that moment carrying current. The anode 9 now being considered is then at a positive potential with respect to the operating anode and to the cathode, and the flow of current is transferred thereto upon the associated control electrode becoming positive. Such control electrode remains positive for a short period of time, the flow of current from the associated circuit thereto being limited by resistors 26 and 21.

'While the associated anode is still carrying current, the control electrode again becomes negative. The control electrode is then able to collectthe charges of positive ions present in the space thereabout, such charges being neutralized by the negative charges supplied by the joint action of battery 24 and winding I8 or, in other words, such charges are removed by the flow of an inverted current from control electrode I! to the control circuit. If the control electrode is of the usual type, such flow of current is without action on the anode current and, when the latter current ceases as a result of the anode becoming negative with respect to the cathode, the control electrode current continues to flow until the space about the control electrode is substantially free of. ions. When the control electrode is given suitable dimensions however, it may collect the charges of ions present in the arc path of the associated anode at a rate greater than the rate of appearance of such ions, the arc path then becomes deionized and the anode current is actually interrupted.

In either case the flow of inverse current through the control electrode circuit causes a voltage drop therein which raises the potential of the control electrode and delays the application thereon of the full negative potential of the source, which is necessary for producing an electrostatic field to prevent renewed fiow of current through the associated anodes until further reversal of the control electrode polarity. As a result of the presence of valve 28, the impedance of the control circuit to the flow of inverse current is reduced to that offered by resistor 21, or even to substantially the resistance of the sources if resistor 21 is omitted, so that deionization may occur freely and application of the negative potential of battery 24 of the control electrode is accelerated. Such action causes the negative electrostatic field to be rapidly established about the control electrode, and the anode is blocked with the least delay, thereby preventing any undesired reattachment of an arc thereto between successive operating periods.

Upon the occurrence of a disturbance causing the flow of excessive current in winding I3, current transformer 33 energizes the coils of relays 3| and 32 with current of magnitude such as to cause operation of such relays. Relay 3| then connects the neutral point of winding I8 with the negative terminal of battery 24, thereby impressing an increased negative unidirectional voltage component on all the control electrodes. Relay 32 short circuits phaseshifter 29, so that transformer le -becomes substantially without c'urrent and simply 'transrnits the negative po tentialof battery 24 to the control electrodes. Upon such occurrence, the control electrodes must also rapidly deionize the space thereabout to prevenhthe re-establishment of the flow of current through the associated anodes, and thereby rapidlycause interruption of the flow of current through valve 6. Such action is also accelerated by the flow of inverse current from the control electrodes through valves 28' instead of through resistors 26. While the operation of the system illustrated in Figure l was described, assuming the system to perform as an inverting system, it will be understood that by suitably modifying the phase relation between the voltages of associated portions of windings II and I8, the system will operate as a. rectifying system, the action of the control electrodes then remaining identically that above described. Such action would also be maintained in any other systems utilizing a valve of the type of valve 6.

The embodiment partly illustrated in Figure 2 is more particularly useful to control the supply to line 3 of alternating current received from line I and rectified in valve 6. In the present embodiment, transformer I9 is shown as being provided with a delta-connected primary winding so connected as to obtain the proper phase relation between the voltages of associated portions of windings II and 18. During rectifying operation of valve 6, the rapid deionization of the arc path about the anodes between successive operating periods thereof is not absolutely necessary and resistors 26 and valves 28 may therefore be omitted. The fiow of current through the control electrodes during the period of positive energization thereof may then be limited by means of a common resistor 31 inserted between the neutral point of winding is and voltage divider 23. Resistor 37 is bridged by means of an electric valve 38 permitting the fiow of current from control electrodes I! to their associated control circuits. A plurality of resisters 39 may be inserted between the contacts of relay 3? and winding 36 to cause rapid dissipation of the magnetic energy stored in the core 22 upon operation of relay 32. Battery 24 is shown as being connected with cathode l6 through a second voltage divider it connected in parallel with voltage divider 23. The positive portion of voltage divider 46 may be short circuited by the contacts of relay 3!, a capacitor ii being connected across such contacts to avoid arcing thereof upon release of the armature of the relay.

It will be understood that, if it is not desired to utilize control electrodes ll for regulating the voltage of line 8, transformer l9 may be omitted and the tap of voltage divider 23 may be moved to the positive portion thereof to constantly impress a positive voltage on all the control electrodes l! and thereby facilitate the attachment of the arc to the several anodes 9 in succession.

Upon occurrence of a disturbance causing operation of relay M, the positive terminal of battery 2-5 is connected with cathode I6 through the contacts of the relay and all the control electrodes then receive only a negative potential of magnitude corresponding to the position of the tap of voltage divider 23. If transformer I9 is present, such transformer is again rendered inoperative by means of relay 32. The operation of control electrodes I! to cause interruption of the flow of current through valve 6 is then Men-- tical' to that of the control electrodes in the embodiment illustrated'in Figure 1 and need not therefore be repeated.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims. Q

It is claimed and desired to secure by Letters Patent:

-1. In an electric translating system, a discontinuously controllable electric valve having an anode with an associated control electrode and a cathode, and a control electrode circuit for said valve including a source of positive and negative voltages, a resistor serially connected with said source to conduct current flowing through said circuit when said control electrode is at a positive potential with respect to said cathode, and an auxiliary electric valve connected across said resistor to conduct current flowing through said circuit when said control electrode is at a negative potential with respect to said cathode.

2. In an electric translating system, a discontinuously controllable electric valve having an anode with an associated control electrode and a cathode, and a control electrode circuit for said valve including a source of control voltages, a resistor serially connected with said source to limit the flow of current through said control electrode when the control electrode is at a positive potential with respect to the cathode, means for maintaining said control electrode at a negative potential with respect to said cathode to cause interruption of the flow of current through said valve, and an auxiliary electric valve connected across said resistor to accelerate the application of said negative potential to said control electrode.

3. In an electric translating system, an alternating current winding, an electric valve of the vapor type connected with said winding and having a anode with an associated control electrode and a cathode, and a control electrode circuit for said valve including a source of control voltages, a resistor serially connected with said source to limit the flow of current through said control electrode when the control electrode is at a positive potential with respect to the cathode, means responsive to an operating condition of said valve for maintaining said control electrode at a negative potential with respect to said cathode to cause interruption of the fiow of current through said valve, and an auxiliary electric valve connected across said resistor to accelerate the application of said negative potential to said control electrode.

4. In an electric translating system, an alternating current winding, an electric valve of the vapor type connected with said winding and having an anode with an associated control electrode and a cathode, and a control electrode circuit for said valve including a source of alternating voltage and a source of unidirectional voltage, a resistor serially connected with said sources to limit the magnitude of the pulsating current flowing from said circuit to said control electrode, means responsive to an operating condition of said valve for modifying the voltages impressed on said circuit by said sources to maintain said control electrode at a negative potential with respect to said cathode, and an auxdirectional voltage connected with said circuits, a resistor serially connected with said sources to limit the flow of current from said sources to said control electrodes, means responsive to an operative condition of said valve for causing said sources to impress a negative potential on said control electrodes to cause interruption of the flow of current through said valve, and an auxiliary valve bridging said resistor for the flow of inverse current from said control electrodes to 10 said sources.

HAROLD WINOGRAD.

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