US2030107A - Electronic relay - Google Patents

Description

Poema Feb. 11, 193s a sneeuwmanc am!! Finn n. Gunmen. minuti", rs., mm1- u Westinghouse Electric & Manufacturing-'Oom- 'I g f v" East Pittsburgh, Pa.,a vcorporation I .vania f my, Pennsyl Application .5, 19.32 y, somma. (ci, irs-'mil ,g L t 1 vme'remis"'1111.this,einem. Precible current" thmushthe s rld re- Sismi'- thereby setting up therein a' voltage drop My inventiony relates to' electrical` relays and has particular relation to relay systems which may bev made responsiveto sudden'changes or impulses in the voltage oi' an electrical circuit `without being ailectedby the absolutefmagnitude oi' that voltage.

w A relay system 'possessing impulseresponsive characteristics'is useful in a number 'ot vapplisirable features and cations, particularly, for example, in' connectiony with'quick-response excitation systems for dy- .name-electricI machines, especially those oi' the synchronous type which may form a part of an altemating-current power system, in that it` permits sudden changes in machine voltage to directly correct the machine excitation without appreciahle delay, the ordinary or more gradual voltage nuctuaticns being takenvcare ofby regulating apparatus oi a conventional type to which the impulse4 relay equipment is supplementary. My invention is directed to the provision of an impulse relay system which possesses the 'de advantages particularized hereinafter.v

One object of my invention is the provision yof a relay system which is lresponsive only to those changes in the voltage of an electrical circuit which take place with a predetermined su deuness or rapidity:

Another object of my invention isthe provision of an impulse-responsive relay system which is unail'ected by and independent of the absolute magnitude ot the voltage of the iniluencing circuit. y

A further object of my invention is the provision. of a relay system of the type described which is applicable to either alternating-current or direct-current circuits.

An additional object of my invention is to provide in a regulating system relay apparatus oi' the type described which is responsive to sudden changes in the voltage oi.' the regulated circuit. l

A still further object of my invention is the provision of an` impulse relay system which .is

particularly suited for application in quick-response excitation systems for dynamo-electric machines.`

` In practicing my invention I dispose interme' diate the electrical circuit and the relay device which is to be actuated upon the occurrence of sudden changes in the circuit voltage, an electronic tube, in the grid-controlling circuit `of which is disposed a resistor through ywhich a capacitor is acted upon by a direct-current potential determined by the circuit voltage. 'Ihe electronic tube is so energized that the output thereof, to which the relay device lsesponsive, is independent of the absolute magnitude oi' the circuit voltage and `is unaffected by gradual changes therein. A rapid change in the .circuit I UNITED STATES PATENT i which acts to materially change Athe.ve'lec'ztronic' tube output:I to' ,causeigthe goesiredrlay! actuation. 5 wnen'if-is desiredgthat thefrelaydeyie remain actuated aftertne 'vonage impulse hasisuhsded. a'second electronic `-tilb'eoftthe' gas-lled or discontinuous control type.' may be disposed mediate the nrst'tube the relay. n o `10` My invention will bestfbenunderstoodiro'xnthe mllowingJ description oi yspeciilclfexnbodixnents thereof when' 1n ,comuna-ion aanmete- Flsurefl is 'a diagrammatic'fview of'apparatus 15 and circuits arranged in 'accordancel ,with .a prei'erred i'orm'I oi my invention. illustrated as forming a part of 'a quickre'sponseexcitaticn system for-a dynamo-electric machine, and,

Fig. 2 is a illustration ofthe 20 impulse-relay equipmentfoi Fig.r 1, showing cern tain modiiication's therein. 1 l f Referring to.'` theV and' more particularly tof .liili-l y1,* thereof,V ,thedmnulse-.responsive relay' system of my invention ilsv shown as a part 25 0i ya. quick-response excitation system for an,a1

ternating-current dynamo-.electricA machine il which has armaturewindings directly connected to the conductors oiathree-phase circuit I2 and` a iield Il which is supplied with exciting 30 current by means ofa directcurrent exciter generatot it. The field winding I'I ofthe exciteru I6 is shown as n being.. energized from a directcurrent circuit comprising conductors I9 andlll, the'potential dierence between which ismain- 35 tained substantially constant.

'Ihe machine `Il may be a generator driven at substantially constant speed by suitable mechanical means (not shown) from which it is desired to supply a substantially constant voltageto the circuit I2. To adjust theA magnitude voltage a rheostat 22 is connected in the energizing cn-enit of the exciter.;nem'windingy l'l'.y An increase in the eld winding .current is eilected by f an adjustment of the. rheostat 22 .in the re- 45 sistance decreasing direction and the voltage of exciter It, which by increasing the current supplied to machine i'leld winding il, ,raises the voltage oi.' machine III.l vIn asimilar manner,"

a rheostat adjustment in the' resistance-increas- 50" ing direction serves to the circuit 'I2'.

` To 'e'ect an automatic adjustment of the rheostat 22 in response to changes inthe voltage of the circuit' n, a rheostat-operating motor' 'u of 55 suitablelreversible type" is shownv as being'controlled by a contact ldevice 2t an actuating 21 which is` viniiuenced, through a positive phase' sequence network le'qui p ment 30, by the voltage o! polyphase circuit I2. 50

to lower thevoltage supplied Networkll,whlchisthssameasthatshown and delci'lbed in VU. 8.`Patent N0. 1,571,224,

granted February 2, 1928to C. TQAllcutt, is for the purpose of supplying a single-phase voltage whichgis dependent upon ali of the phase voltages of circuit i2 rather than upon any individual one toinsurethattheregulatorresponseatalltimes be representative of the` elective or average circuit conditions. s.

mnemrknaenernsedthroghvoltasetransformers l2 connected in open delta to the conductors or' threepbase circuit Il. The sec- Inoperation of the regulating equipment thus fardescribed,whichisshowninahighlysimpli nesiforni,whenthevoltageofmachineIlisofl the dired value, contact making device 2l occupies the neutral position shown, and no operationofrheostatmotorltakesplace. Adecrease belowtbe desired valueofthisvoltage causa device 2i to complete through contact member R an energizing circuit formotor 2l which then opcrates rheostat Il in the voltage-raising direction to appropriately correct the machine voltage. Similarly, an increase above the desired value e of the machine voltage causes the completion through contact member L of a motor `energiziing circuit which adjusts the rheostat Min the voltage-lowering direction.

`The rate of excitation change which a conventional regulator. of the type described, is capable of electing is relatively slow, and when the regulated machine forms a part of an'alternatingcurrent power system sudden load demands or other abnormal conditions may result in instability unless supplementary quick-response meansbeprovidedlnthepasttheexpedients resortedtoforthepurposeofobtainingsuch quick-response excitation have been subject to the disadvantage of having a certain amount of delay in their operation, a typical arrangement (not shown invthedrawing) being to provide held-circuit resistance shunting relays which are controlled by lthe circuit-influenced contactmaking device (2l) in auch manner that an excitation change is elected in advance of the necessary adjustment of the Vmotor-operated rheostat (22). Assuming that when the "lower" v contacts of the device are engaged, a sudden drop in circuit voltage occurs, before any excitation correction can be elected it is necessary that.

thefcontact-carrying arm of the device move to the-other limiting or "raise" position. I'he time required for nsuch movement to be elected represents a substantial delay, which delay tbe improved relay -system of my invention is capable of overcoming. h

The need for a rapid excitation adjustment is more pronounced upon a sudden decrease in the machine voltage than upon a sudden increase in the voltage, the requirement then being to very rapidly mise the macine excitation, and the impulse-responsive relay system of my invention is illustrated as beingdisposed to fulilll this rewhich aosonov 1 theoccurrenceofasuddendecreaseinthevoltage ofcircuit il.

Tne relav l. comprises an actuating winding is supplied with energizing current through a grid-controlled gas-nlled electronic tube Il. The tube M in turn is -inil'uenced by`a second electronic tube II which is preferably of time triode vacuum or amplifying type. The tube II is acted upon by a unidirectional voltage de-J rived from a resistor Il across which is impressed a unidirectional voltage which. at all times, is proportional to the alternating-current voltage appearing between conductors II and I1, and is a measure of the average phase voltage of cir- `'lhis unidirectional potential is supplied from the conductors named through a transformer Il, having secondary windings Il and i3 which feed into a full-wave rectifying tube $2 oi' well-known W, which. together with filtering equipment Il, causes the desired unidirectional voltage to appear between conductors li and Il, which, in the mtem shown, yis substantially proportional to the voltage of the polyphase circuit Il.

Apotentialisimpressedupontheanodeelement il ot the amplifying tube Il of such value astomakeitpoaitive withrespecttothecathode element il. This. potential is supplied from the portion of direct-current energized resistor Il below tap connection Il through a circuit which includes a resistor I0. The grid element Il of the tube is energized by a negative potential. from the portion of the direct-current energized resistor Il above the tap connection Il through a circuit which includes a resistor M. The magnitudes of these two potentials are so chosen that,

as the voltage between conductors ll andA 56 changes, the potential caused to appear between points 'il and 1I, which potential controls the tube M, will remain substantially constant. This is accomplished by the fact that as the anode voltage is, for example, increased the grid voltage becomes proportionally more negative, increases the repulsion by the control-grid element of the electrons liberated by the tube cathode, and thus checks the tendencyfor the anode current to rise.

The tube Il, which is of the gas-lilled type. comprises anode and cathode elements t1 and il, respectively, connected in a circuit with the actuating winding of relay I which is energized from the direct-current control circuit conductors I! and 2l. When the grid element 1I) of the tube is maintained at a negative potential, with respect to the cathode,and exceeds a given critical value, which'in practice is oi the order of several volts, the tube is maintained non-coniy ductive and no current ilows between the anode and cathode elements. However, when the grid bias is reduced below this critical value, conduction between the anode and cathode starts and continues until the anode circuit is interrupted. Thus, in the system of Fig. l, as long as the4 g'rid 10 of tube Il is maintained sufilclently negative, the actuating winding of relay lll will remain unenergized.

In the system ot Fig. l, this negative bias applied to tube Il is determined by the excess of the voltage drop through resistor 60 over that through the portion of direct-current energized resistor Il below tap 'connection 13. The purpose of 'the inclusion in the circuit of a portion of resistor Il is to compensate for deviations from a constant value of the anode current of tube 46 as the voltage across resistor 48 changes in a gradual manner. These resistors are` soproportione'd that normally this excess will be suiiiciently above the critical value. for tube M to maintain the tube non-conductive. v'II.'husa gradual change through a Wide range in the voltage of circuit I2 will be prevented from eil'ecting the actuation of excitation-raising relay Il.

In order that sudden drops in the voltage of circuit Il-may be instrumental in actuating relay 48, I provide, in association with the grid'clrcuit of amplifying-tube 4 8,v al capacitor 18 which is actedupon through the resistor 8l by the'voltage which energises the resistor 48. Gradual changes in the magnitude of the potential between conductors Il and- I8 cause only a small capacitor current to ow through the resistor 8l setting up therein a voltage drop insumcient to materially unbalance the proportional change yrelation between the tube grid and anode potentials. More appreciable changes in the anode current of tube Thus, in operation oi the complete impulseresponsive relay equipment shown in Fig. l, a rapid fall in the voltage of circuit I2, by directly lowering the direct-current potential impressed upon resistor 48, causes capacitor 18 to circulate through resistor 88 a discharge current which has a direction indicated by the arrowpwhich discharge current sets up in the resistor a voltage drop in such direction that the value of negative bias applied to the grid element 88 ot tube 48 is abnormally increased. 'Ihis abnormal increase effects a corresponding reduction in the magnitude of tube anode current which iiows through resistor 88, with the result that the voltage drop through the resistor is decreased to a point where the potential impressed upon the grid element I8 of tube Il, through a resistor 18,lsallowed to fall below the critical value .and the tube `ixnmediately becomes conductive.

By virtue of this conduction, the energizing circuit for the actuating windingof relay 48 is completed, causing the relay to bias upwardly to the closed position, a contact member '80 which shunts rheostate 22 from the energizing circuit of exciter ileld winding I'I, and thus ,raises the excitation of regulated machine Il. T'he tube u remains conductive until the current supplied to iield winding I4 of machine I8 rises to a predetermined value, at which time, a current-responsive relay 82 disposed in the held-winding circuit, actuates a contact member 88 thereof upwardly toy interrupt the anode circut of tube Il and thus effect the deenergization of relay III. Such deenergization having been effected, the excitation control is returned to the motor-operated rheostat 22.'

In Fig. 2, I have illustrated a modified form of impulse responsive relay equipment which fundamentally is the equivalent of that shown and described in connection with Fig. l, but which possesses certain additional advantages thereover ln that the characteristics of the electronic tubes utilized therebygiov` not have to be so critically taken into account as in the system of' Fig. 1.-'

[n the schematic diagram' of'liig. 2 the directcurrent voltage across resistor V48 is, as in the prportiQl t the volta-8691 l i f means forenergizingvsaid v.ariodeancl grid circuits inl accordance `with potentlalS kderived from 1 said electrical circuit (in such vznannerthat the anode-circuit current`- remains substantially consystem ofFig. l,

circuit I2.

The ampliner tubefle is connected to 'resistor 88' Vin suchlxnarincry thatj'the anode current of tube lo does not/change as the regulated voltage v changes slowly, `this obtained by selecting sible.

the location of tap 8i so that any change in, tube anode voltage is compensated for by a proportional change in grid bias voltage. 'I'he resistor 84 and capacitor 18 are connected in a discharge Vcircuit to the grid element 63 of tube 48 so that i'ordecreasing regulated voltage the tube grid voltage drop across resistor 68 will decrease, due to the decreased plate current of-tube'. When the voltage drop V'aucross resistor elif decreases a voltage drop :will obtain across resistor 8 5, due to the, discharging action of a capacitor 81. The polarity of the voltage drop across the resistor 85 will be as indicated in the diagram, so that the grid voltage of the gas-lled tube u becomes more positive and 'causes the tube to break down and energize the winding of the quick response shunting relay 40.

The relay 48 remains closed until the directcurrent supply voltage for tube 44 is disconnected by means of contact member 83 of the field-current limiting relay 82. 'I'he direct-current supply for the tube 44 is supplied from the control circuit conductors I8 and 20, through the voltage divider 80, the negative bias for the tube grid element, being derived from the right-hand portion of the divider resistor and the positive anode potential from the left-hand portion.

As above pointed out, the system of Fig. 2, by virtue ofthe modied scheme of grid control for the tube 4l just described. is more exible and less responsive to changes in the tube characteristics than is the scheme of Fig. l. Either of the two schemes are capable of response adjustment by changing the relatlve values of resistor and capacitor elements 6l and 15, or as in the system of Fig. 2, by adiusting the magnitude of voltage which acts upon capacitor I6 through theuse of a tap connection 82.

Although the impulse responsive relay equipment of my invention has been illustrated in quick-response excitation system for a dynamoelect-ric machine, it will be apparent that itis in no way limited to this one particular application, nor is it limited to relay actuation only in response to sudden changes in the voltage lowering direction of the regulated circuit. For example, in the event that voltage impulses in `a direct current circuit are to be detected, circuit conductors 55 and 56 could be joined directly to the circuit instead of beingsupplied through the intermediate apparatus shown in the drawing. It will be apparent therefore, that the equipment is exceedingly flexible in its application.

A Although I have shown and described certain specific embodimentsof my invention, I am fully aware that many modications thereof are pos- My invention, therefore, is. not to be restricted except insofar as is necessitated by the prior art andby the' scope of the appended claims.

I claim as myinvention:

l. In combination with a variable-voltage electrical circuit and,l a relay iniiuencedthereby, means for causing the relay to respond to voltagechange impulses, comprising an electronic tube havingan anode, acathode, and aigrid element,

a circuit including Asaid anodeA and cathode elements for controlling the actuation of. said relay,

4 gradual cames 1n the electrics; smut voltage. s

` resistor connected `in said grid circuit. and a capacitor connected through said resistor to said electrical circuit for energization in accordance with the voltage thereof,the effect of said connection being Vto modify the tube grid potential in such manner that when-the said electrical-circuit voltage changes at a rapid rate in the voltagei decreasing direction an actuation of the abovementioned relay will result.`

2.4 In combination, an electrical circuit, an electronic tube, means for so connecting said tube to the circuit that the output current of the tube varies only upon the occurrence of rapid changes in thevoltage of the circuit, ay second electronic tube, a relay device connected to said second tube for energization in accordance with the output varies only upon the occurrence of rapid changes in the voltage of the circuit, a second electronic tube, a relay device connected to said second tube for energization in accordance with the output current thereof, means for im upon said second tube a control potential which maintains it non-conductive, and means responsive to changes in the output current of said first tube which result from a rapid decrease in said electrical circuit voltage for modifying said control potential in a manner to rendervthe second tube conductive, said last-named means'comprlsing a resistor and a .capacitor connected in series for energization by a potential determined by the output current of said iirst tube, said resistor being connected tomodify the control potential applied to the second tube.

4. In combination with a relay and a source of potential, means for causing said relay to be responsive to sudden changes in the potential-decreasing direction in the magnitude `oi' said po- `tential and to be unailected by tbe absolute value thereof comprising an electronic tube, a circuit connecting the relay to said tube in a manner to eiiect actuation of the relay when the tube ris rendered conductive. a second electronic tube connected to render said. nrst tube conductive the output of the second tube exceeds a given value, said second tube being oi the triodetype ,l and having associated therewith anode and grid circuits, means for so connecting said circuits to said source of potential that the tube output remains below the said given value throughout a wide range of steady state values of the potential, a resistor connected in the said tube grid circuit, and a capacitor energized by the potential ofsaid source through a circuit which includes said resistor, the eflect of said resistor and capacitor when so connected being to cause the tube output to increase when the potential ofV said source decreases ata rapid rate.

5. In combination, an electrical circuit, an electronic tube having anode and grid elements connected to be energized in accordancewith potentials derived from said circuit. said connection being such that variations in the voltage of the cir` cuit which produce changes in the negative direcaoscnov tion in the potential supplied to the tube grid also produce changes inthe positive direction in the potential supplied to the tube anode. and vice versa, to thereby cause the anode current of the tube to be independent of the steady state magnitude of said circuit voltage. a relay, means responsive to changes in said tube anode current for controlling the actuation of said relay, and means responsive to rapid changes in said circuit voltage' in the voltage-decreasing direction for so. moditying the potentiall impressed upon the grid element of the tube as to produce a relay-actuating change in the tube anode current. u

Vii. In combination, an electrical circuit, an electronic'tube having anode and grid elements connected tobe energized ,in accordance with potentials derived from said circuit, said connection *being such that variations in the voltage of the circuit produce changes in opposite directions in said two potentials to thereby cause the anode current of the tube to be independent of the steady state magnitude of said circuit voltagepa relay, means responsive to changes in said tube anode current for controlling the actuation of said relay, and means, comprising a resistor connected intermediate the tube grid element and its source of potential and a capacitor energized through said resistor by a measure of said circuit voltage, for causing rapid changes in said circuit voltage in the voltage-decreasing direction to so modify the tube grid potential as to produce a relay-actuating change in the tube anode current.

7. Means for causing a relay device to be responsive to sudden changes in a decreasing direction inthe voltage of a direct-current circuit comprising, in combination, an electronic tube having anode and grid elements connected to be energized in accordance with potentials derived from said circuit, said connection being such that the anode current of the tube will be maintained sub- I stantially constant as the voltage o! said circuit gradually changes, a relay, means responsive to changes in said anode current for controlling the actuation of said relay, and means, comprising a series-connected capacitor and resistor energized by a measure of said circuit voltage, adapted to vary said tube anode current upon the occurrence of a predeterminedly rapid change in said decreasing direction in the magnitude. f said circuit voltage, said resistor being connected between 1 the tube grid element and its source of potential and acting to modify the voltage impressed upon said grid in accordance with the current which the capacitor allows to pass through the resistor.

8. In combination, an alternating-current cirl cuit, an electronic tube having anode and grid elements, rectifying, means for supplying from said alternating-current circuit direct-current potentials to said tube elements,` said potentials being so interdependent that the anode current of the l tube will be maintained substantially constant and of an appreciable magnitude asthe voltage of the alternating-current circuit gradually changes, arelay. means responsive to predetermined changes in said anode current for controlf ling the actuation of said relay. and means for so predeterminedly varylng'said anode current in accordance with the rate of change of said circuit voltage in a decreasing direction, said last-named means comprising a resistor connected intermediate the tube grid element and its source of potential and a capacitor energized through said resistor by a direct-current potential supplied from the circuit through said rectifylng means.

- FINN H. GULLIKSEN.

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