US2490048A - System and process for the remote control of selectors or similar units - Google Patents

Description

Dec. 6, 1949 Filed Aug. 6, 134'? F. P. GOHOREL 2,490,048

SYSTBI MED PROCESS FOR THE REMOTE CONTROL 9F SELECTORS OH SIMILAR UNITS.

3 Sheets-Sheet l INVENTOR FERN/4ND P/f/PlPf GOHO/PEL WwyL ATTORNEY 6, 1949 F. P. GOHOREL SYSTEM AND PROCESS FOR THE BEMOTE CONTROL or SELECTORS on sum. mum's Filed m. s. 1947 s Sheeizs-Sheet 2 L RE Wm NE W 4 m M A N m F ATTORNEY 1949 F. P. oHaRE'L SYSTEM AID PROCESS FOR THE REMOTE CONTROL Filed Aug. 6, 1947 T3? SELECTORS OR SIMILAR UNITS 3 Sheets-Sheet 3 s sh Ei o o o W 0 o o --:0 o 0 III ATTO R N EY Patented Dec. 6, 1949 SYSTEM AND PROCESS FOR THE REMOTE CONTROL UNITS OF SELECTORS OR SIMILAR Fernand Pierre Gohorel, Antony, France, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application August 6, 1947, Serial No. 766,692 In France November 6, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires November 6, 1965 Claims.

The systems are well known in which a selector may be directed, from a remotely located control device, to a given position (or group of positions).

To this end, the selector is equipped with a set of marking contacts whichare scanned by a suitable scanning device, each position (or each group of positions) being characterized by a potential, the nature of a current or the phase angle of an alternating current applied to the corresponding marker contact. Means also are provided for the rotation of the selector to continue until such time as there exist a given relationship between the electrical condition of the marker contact and that of the control or directing device.

It is quite obvious that where'the number of positions (or of groups of positions) is a large one, it becomes difiicult to secure, for the marker contacts, such electrical conditions as lend themselves to simple identification. This had led to the use of electronic means,endowed with great sensitivity, but at the same time difiicult of construction and critical of maintenance.

On the other hand, it is well known that, in a general sense, an electromagnetic relay of suflicient sensitivity to attract its armature with great rapidity does not release it with the same speed when its circuit is opened, this delay upon release becoming more substantial still when the current passing through the relay, instead of falling to a zero value,- merely assumes a magnitude smaller than that of relay energization or operation.

Under such conditions, any relay which attracts its armature in the selector positioning unit, during the scanning of the marker contacts, while the scanning or hunting member passes on a position (or group of positions) at which the selector is not supposed to stop, will not immediately drop its armature as the scanning member leaves the position (or group of positions) just alluded to. Furthermore, if the speed of said device be of sufficient value, which is prac tically the case of selectors, such a relay thus may cause false positioning during the scanning of the following marker contacts.

One of the characteristics of the invention will be found in the fact that the marking potentials are so arranged that, bearing in mind the scanning order of the corresponding marker contacts, it be not necessary to energize any relays upon passing the position (or group of positions) which precedes the one at which the selector must be stopped.

A process for the adjustment of a selector having n positions (or 11 groups of positions) in ac-:

cordance with the above mentioned characteristic is obtained by the following combination in which:

1. Use is made on n1 sources of direct current at the same potential u, series connected, which gives n potential levels or steps.

2. If the n marker contacts of .11. positions be designated by l, 2, 3, 4'. n, counting in the order of their scanning, they are connected to the potential steps according to the following rule: contact I to 0 potential, contact 2 to are rounded off to the nearest integer below the actual figure obtained.

3. A provision is made, in the directing or orienting device, inserting them in the directing or control circuit, for two series or parallel connected relays, the first of one is capable of attracting its armature at a potential difference equal to 11 while the second, or marginal one, is capable of attracting its own armature only for a potential difference of 2a. Said relays are connected, on the one hand, with the scanning device of the selector marker contacts and, on the other hand, with a potential lever l or step which depends on the position at which the selector is to be stopped, provisions being made for them to be energized only by a current circulating in a given direction.

4. Scanning of the selector is caused throughout the time during which, either the first relay is not attracted, or both simultaneously attract their respective armatures.

Another process which is an application of the characteristic indicated above and which makes 9...; 1. Use is made, for the marking of n groups of positions, of 1; sources ofdirect'current,

of which have their negative'term-i-nals connected to a common point, while the'remaining common point. The voltages of the positive sources are all different from one another but may be respectively equal to the voltages of the negative sources. One thusiprovides 2 steps of positive potentials and steps of negative potentials.

2. The

groups are connected to the negative (or positive) potential steps or levelsFWhere n is odd, two consecutive groups of marker contact groups are connected to two positive *(or negative) steps in such a manner that the step having the lower voltage precedes, in the direction of scanning, the one having the'higher voltage.

3. A provision is made, in the controlling or directing device, for several relays connected either in series or in paralleland capable of operating only with a given direction of current, the armature attraction or .-nonattraction of .said relays being dependent on-thepotential difference applied to their terminals. These relays are connected, on the one hand, to the scanning device of the selectorand, on the other hand, to the common .point of all the current sources and the current direction for which they are attracted, as well as their attraction .or non-attraction'combinations, depend .onthe group of lines or-on the line to which the :selector is to be dirooted.

4. Scanningof the selector and its positioning are controlled according to the attraction ornonattraction combination of 'th'e'relays of the p'ositioning or direction device.

In the process outlined above, the common point of the current sources, aswell as one of the terminals of therelay 'group' may be grounded, which does away with the need for a connecting wire between" the selector and thedirecting device. This arrangement is of particular 'advantage when the selector and'the directing device are not installed .in ais'ingle room (such as is the case, for instance, in'telephone networks having several central oifices) 4 Another process, according to .the characteristic of the invention, "which makesit possible substantially to reduce the number of the potential steps, and thus the precision needed in the operation of the control relays consists, in com- 1 bination with-the processes discussed above, of the following:

have their positive terminals connected -to said 1. An alternating'current source or several alternating currentsources having different voltages or frequencies are connected in series with -rent marking potentials, the superimposition of a single alternating current on each direct current source will provide 211. marker steps, while, with twos'ourceisoi alternating current, the number of-marker steps would be raised to 3n.

2. The marker contacts of the selectors, in their order of scanning, are alternately connected to a direct current potential step and to a potential step obtainedby means of the superimposition-of the alternating current source on the direct current source used for the preceding marker contact. The order of the direct potential steps ischosen in the manner which has been outlined above with relation to another process. In cases where several alternating current sources are available, the various potential steps obtained by the superimpositionfto a direct current,'of each one'of the alternating current sources, are connected'in succession to a series of the selector marker contacts before another direct current potential level is connected. to the next contact in line.

3. Scanning'of these'lector and'its'position are controlled by the action of 'relays which are responsive, not 'only"to direct current, but also to alternating current.

In combination with theabove outlined processes, it is possible further "to increase the number ofthe positions which can be assumed by the selectors, when't'hey are equipped with a drive mechanism of "thestep-by step type, and when call'number'reg'istered by the controlling or dirooting-device. Such,for-inst'ance, is the case oi the line selectors or final selectors used in automatic switching "telephony.

According to the "inventiomthe selector is divided into groupsyeach of which comprises a certain number of positions, the first of which in turn is marked by a potential level or step, and to which the selector may be directed or positioned by the controllingor directing device in accordance with one of the processes which have already been described above. When this preliminary positioning' or directing has been completed, the controlling or directing device sends out "as many impulses asare'needed to cause the selector to 'movea'he'ad'to the final position to 'which it is tobe directed. The controlling or directing device of the'selector is placed in series; for the preliminarydirection, with-a rectifier which passes only one current alternation and a sourceof alternating current'while, for the final positioning or directing, itis connected to an imp-ulsing contact andasource of direct current.

Various'embodiments of the processes outlined, in'a'ccordance with the principles of the invention, will no'w'b'e described as non-restrictive examples/in relation with the appended figures. These figures show only such circuit elements as are necessary for an understanding .of the invention.

In the directing process of Figure 1, two relays A and B are provided in directing device 0. These relays'are inserted in a circuit which is connected, on the one hand, to the scanning device of selector S, namely wiper F and, on the other hand, to unilaterally conducting elements Q1 and Q2. According to the number received by the controlling or directing element, one of contacts sal to $115 is closed. Relay A can attract its armature when there is a potential difierence equal to u and relay B can attract its own armature only when such potential difierence as is present is equal to Zn.

Marker contacts l to 5 of selector S are connected as shown on the figure.

It will now be assumed that contact sa3 is closed, namely that selector S must be directed to position 3. When director and selector S have been connected, the circuit of drive electro-magnet R is closed through rest contact al of relay A. When wiper F reaches the third position, the following circuit is completed: negative polarity on Us at contact 3 of S, wiper F, relays A and B in series, unilaterally conducting element Ql, closed contact sat and positive polarity on battery U3. Relay A attracts its armature and relay B remains at rest. Through its rest contact al, relay A opens the circuit of drive electro-magnet R. and selector S stops at the third position.

Through its work contact al, relay A completes, by way of rest contact bl of B, the circuit of relay C, which causes, in the directing or controlling unit, the operations which follow the stopping of the selector.

The case will now be taken up of the possibility of false positioning when wiper F passes on bank contacts 1 and 2.

When wiper F passes on bank contact I, the

following circuit is completed: negative terminal of battery U4, contact I and wiper F, series connected relays A and B, element QI, contact sa3, positive terminal of battery U3. Since the two batteries, U3 and U4 are connected in series in the circuit relays A and B will attract their respective armatures. Through its work contact b2, relay B completes the circuit of R, which is open at al. Selector S thus will continue the scanning motion. Through its contact I), relay B makes a break in the circuit of C and this last mentioned relay can not be energized.

When wiper F passes on position 2, the positive polarity of U2 is placed on said wiper. The circuit of relays A and B cannot be completed due to the fact that element Q2 is not placed in the circuit. Relays A and B drop their respective armatures and S continues the scanning.

It will be observed that relay B, which had been energized at position 1, drops its armature at position 2 or, in other words, there is no need for any energized relay at the position which precedes the one to which the selector must be directed. By having reference to the directing or controlling circuits, it will readily be seen that stopping is effected by the energizing of relay A, at position 1, through Ql (U4); at position 2, through Q2 (U2) at position 4, through Q2 (Ul and at position 5 through Ql (U2). Furthermore, there can be no false positioning.

Figure 2 shows a variation on the process of Figure 1, which makes it possible to reduce the number of the wires needed between the direct ing or controlling unit and the selector.

A certain number of batteries U3, U2, Ul, U'l, U2, etc. are arranged in selector S, having the same voltage u and connected in series, the common point between batteries UI and U'l being grounded. This constitutes a certain number of potential steps or levels, namely 6 in the example under review, which are respectively equal to 3u, 2u, u, 0, +u and +2u. The negative potential steps or levels are connected respectively to the bank contacts associated with wiper F of selector S on odd positions 1, 3 and 5, while the positive potential steps or levels are respectively connected to positions 2 and 4.

It will now be assumed that contacts sa3, sb3, s03 are closed, namely that the selector has to be directed to position 3.

' As soon as directing device 0 is connected with the selector S to be directed, the following circuit is completed: battery, electro-magnet R, contact s03, rest contact al associated with relay A, ground.

Electra-magnet R then causes, according to a well known process, the progression of its wipers in automatic rotation. When said wipers reach position 3, the following circuit is completed: negative terminal of battery U2, bank contact and wiper F at position 3, unilaterally conducting element Q2, contact sa3, left hand windings of relays A and B in series, ground and, in selector S, ground and the positive terminal of battery Ui.

Relay A has been so designed that it attracts its armature only in the presence of a voltage equal to 2u at least, if it is energized on its left hand winding and to u if it is energized on both of its windings. Similarly, relay B has been so designed that it is energized by a voltage equal to Bu at least, if working on its left hand winding and 21L if working on both windings. Relay A thus will be the only one to attract its armature, since the above outlined circuit closes through two batteries, each of which has an E. M. F. equal to u; it opens, at al, the drive circuit of the selector and completes, by way of its work contact a2, the following circuit: battery, relay C, contact sb3, work contact a2, rest contact 132 associated with relay B, ground. Relay C is energized and causes, within the directing or controlling unit; the various operations which follow, the stopping of the selector.

Even as was the case with the arrangement of Figure 1, let us now review the possibility of false positioning when Wiper F passes on positions other than position 3. When it passes position 1, the following circuit is completed: negative terminal of battery U3, bank contact and wiper F at position 1, unilaterally conducting element Q2, contact sa3, left-hand winding of relays A and B, ground and, in selector S, ground and positive terminal of battery UI. Relays A and B are both energized, due to the presence of a potential diiference 32L; at al, relay A makes a break in the drive circuit of the selector but, by way of its work contact bl, relay B restores continuity to said circuit and the selector continues its progression. Relay C being of the delayed attraction type, remains at rest, even if its circuit has temporarily been completed at b2 and a2, due to the non-simultaneity of the operation of relays A and B. When the selector passes position 5, relays A and B, the circuits of which are completed only through battery Ul, remain at rest and the progression of said selector continues. When the selector passes even positions 2 and 4, batteries U'I and U'2 are the ones to intervene, but the circuit of relays A and B can not be compl ted :clueo the. presencaoi nle laterally conduc in I elemen Q2.

It will be observedtbat r lay e ergiz d at. Position 1; has all he-needed time tor piti armature t posit-1on2. thisdoes notp e risl; of being. held at position 3, which would make it impossible for the. selector -to,-stop.

A study of the various directing rc ntrollin circuits will show that stoppin isscaused ,bythe energizing of. relay. .A,1'at position, through bate tery l. r fi r-:Ql'andthe two series: connected windingszof.Aaatposltio l; throu h UZzi and Q l, .at position .5, through. U1 andaQZ. False positioning is made impossible-due tothe fact that, on the even numbered positions, the circuit'of relays A and B can be completed only if the directing or. controlling unit is on anodd numbered position due to; the presence jot-one of the two unilaterally conducting elements. QI- and. Q2 and conversely. .On the. other. hand, when rectifiers 6.2!. and Q2 do not oppose he passage of current, the voltage is either. too weak, which makes itimpossible for relay. A..to be energized, or too high, which causes relay B to be energized and the progression of the. selector to.

continue.

When the selector has to be directed .to position 1, contactssal, sbl.,. scl are closed, thedrive circuit passes through: battery, electroemagnet R, contact scl,.rest contact bl,.ground, stopping being effected by relay B, which is:ener ed through. batteries. U1, U2, U3, rectifier Q2 and contact sal. The circuit. of relay C then is com pleted through b2 and sbl. False position ng or directing is impossible for the very reasonswhich have been discussed in the above paragraph.

Figure 3 shows a device which makes it pos sible to direct a selector to 211. positions by making use of only 11. batteries,

of which (Ul, U2, U3) have theirpositive tep minal connected to a common point which is grounded in the example illustrated, and'the other of which (U'l, U2, U'3) have thelrrnegative terminal connected to said common point. The

voltages of batteries Ul, U2, U3 are'different from one another but may respectively be equal to those of batteries U l, U2, U3. In order to. make mat ters clearer, let ul, a2, a3, u I, u2, u3 be. the respective voltages of batteries Ul, U2, U3, Ul, U '2=,' U'3 with:

The negative terminals of-batteries U1, U2, U3 are respectively connected to positions 1, 5 and 9 of selector S while the positive terminals of Ul, U2, U'S are connected to positions 3, 7 and 11. Each even numbered position is connected to the odd position which immediately. precedes; it through an alternating current generator which may, by way of example, be one of the windings of the secondary of a transformer T. Rela Ahas been so designed as to attract its armature with a voltage equal at least to a2, if its left-hand wind ing is the only one in the circuityand with a voltage equal to 11.3 at least, if bothwindingsare functioning. Relayv B has been designed to at? tract its armature for avoltagesequalto uliat' least if its leftrhand' wind n s the. only o e n the circuit and for a voltage equal at least to a2. ifboth. windingsare in the, circuit,

Let it be assumedthat the selector must be directedto-position 5; contacts m5, sb5, s05, sd5, set, of the directing or controlling element 0 then are. closed. 'Assoon as said controlling unit is connected to selector S, which is to be directed or positioned, :the. following circuit is completed: batteryadrive electro-magnet R, contast s05, rest contact a! associated with relay A, ground. The drive electromagnet B causes the selector wipers to move ahead in automatic rotation. When said wipers=reach position 5, the following circuit is completed: negativeterminahof battery U2, bank contact-andwiper F- of the selector at position 5,

unilaterally ,conductingelement Ql, contact sa5, leftehand windingsof relays A nd B. conn c in series, ground; and, in, selector r un d positivev terminalqofy battery U2. The voltages needed to energize; relays A and B on the left-hand winding are, respectively, a2 and ul, so that relay A is the only one to attract its armature, closing :at: a2 the vfollowing circuit of relay C: battery, relay C, restcontact (12, associated with relay D, contact 3225, Work contact o2, rest contact 122.. associated with relay B, ground. Relay C is energized causing, in the directing or controlling unit,.the various operations which follow the stopping of the selector.

.Itisimpossible for. said selector to stop on any position but the fifth. It we take position 1, we see-that battery U5 is the. one to intervene so that relay Bis energized at the same time as relay A and causes, through its work contact bl, the re-starting of the selector. At position 9, battery U3 is. placed in the circuit and relay A itself is unable to become energized with the flux generatedby. its left-hand winding only. At positions 3, 7. and .11., batteries U l, U'2 and U'3 are the ones placedinthe. circuit; relays A and B can not be energizeddue to the presence of'unilaterally conducting. element Q1. At positions 2, 4, 8, 10, 12, false positioning is ruled out for motives identical to .those whichoppose stopping at the odd numberedposition which immediately precedes them. The. alternating currents generated by windings tl to t6 willbeso chosen as not to cause unwanted operation of'relays A and B. At position 6 which immediately follows position 5., or the stopping position, the following circuit is completed: negative terminal ofbattery U2, winding t3, bank contact and wiper F at position 6, unilaterally conducting element QLcontact sa5, left-hand Windingof relays A and B, ground and, in selector S, ground and positive terminal of battery U2, winding t3, bank contact and wiper F at position 6, workcontactaS, contact se5, capacitor 0, bridge rectifier such as madeup of elements Q3 to Q5, ground. .Relay D is energized due to the effect of the rectified current and completes, by way of its work. contactsdl and sd5, the drive circuit of the selector, which otherwise-would be open at at; .by the opening of its rest contact d2, it opposes the unwanted energizing of relay C. It will be noted that, according to the invention, none of relays A, BandD has its circuit completed at position ,4 of'the selector, which immediately precedes stopping position 5.

It-will now be assumed that. the selector has to be directed to an even numbered position, position 6 for instance. Contacts safi, sbfi, s06, sdfi, sefi, are closed. When the selector moves on to position 6, the following circuit is completed: negative-.terminal'of battery U2, winding t3, bank contact and wiper F of the selector at position 6, unilaterally conducting element Ql, contact sat, left-hand winding of relays A and B, connected in series, ground; and, in selector S, ground, positive terminal of battery U2 with, in parallel across the circuit outlined above, contact seB, capacitor C, relay D through bridge rectifiers Q3 to Q6, ground. Relay A is the only one to be energized, to the exclusion of relay B, for reasons explained elsewhere; the alternating current, on its side, causes the operation of relay D, after its rectification by bridge rectifier Q3, Q4, Q5, Q6. The drive circuit of the selector is open at al and dl. Relay C is energized by way of: battery, relay C, work contact d2, contact sbli, work contact (12, rest contact b2 and ground.

No false positioning is possible; at positions 1 and 9, the voltage is such that relays A and B both attract their armatures or both remain at rest. On positions 3, 7 and 11, rectifier Ql makes it impossible for relay A to be energized; at positions 2, 4, 8, 10, 12, the reasons which make it impossible for the selector to stop are the same as those which rule out stopping at the odd-numbered positions which immediately preceded them; at position 5, which immediately precedes the stopping position, the drive circuit of the selector is completed through rest contact dl, associated with relay D and edit.

Study of the various directing circuits will show that stopping of the selector is effected at position 1, by the energizing of relay B through its left-hand winding, through battery UI and rectifier Ql, at position 3, by the energizing of relay B on its left-hand winding through Ul and Q2, at position 5, by the energizing of relay A on the left-hand winding through U2 and Ql, at position 7 by the energizing relay A on its left-hand winding through UZ and Q2, at position 9, by the energizing of relay A on both of its windings through U3 and Ql, on position 11, by the energizing of A on its two windings through U'3 and Q2. At any even-numbered position, stopping is effected as at the odd numbered position which immediately precedes it with, in addition, the energizing of relay D.

It will also be noted, generally speaking, that the selector can not stop at a position different from the one required; either the direction of flow of the current is such that neither relay A nor relay B can be energized and rotation is continued through rest contacts al and bl, or else the battery tension applied to the circuit is too high, which causes relay B to be energized and the rotation of the selector to continue by way of work contact bl; or else the voltage of the battery placed on the circuit is too low, neither of relays A and B being able to attract their respective armatures and rotation being continued by Way of cl or bl, or again the position'on which the selector is even, rather thanodd numbered, which causes relay D to be energized through one of contacts a3 or b3 and the rotation of the selector still to continue through work contact dl; or, finally the position passedby the. selector is odd, rather than even numbered, in which case relay D remains at rest and causes rotation to be continned by way of its rest contact dl.

It will also be seen that, according to the invention, no relay which might cause unwanted rotation has its circuit completed at the position which immediately precedes the stopping position, neither relay A nor relay B, due to the presence of unilaterally conducting elements Ql and Q2, nor either relay D, due to contacts a3 and b3.

It has been assumed, in the above discussion, that the voltages of batteries Ul, U2, U3 were respectively equal to those of batteries U'l, U2, U3. It is obvious that this condition is not by any means indispensable and that the voltage of battery U'l, for instance, may be smaller than that of battery Ul, provided there be a suflicient margin between said voltage and the one immediately smaller, namely a2 or u2.

Figure 4 shows a directing or controlling device which embodies a combination of the processes described above and the process whereby directing is effected through the sending out of impulses. The selector illustrated comprises a certain number of positions which are grouped in tens; for the clarity of the illustrations, only tens numbers 1, 2 and 3 have been shown, as well as only the four first positions of each ten. The first positions of each ten, say 10, 20 and 30, are connected to batteries U3, U2, Ul U I, UZ, which are arranged similarly to the manner in which they are shown in Fig. 2, although any one of the above described processes might be used, while the bank contacts associated withwiper F at the other positions are insulated. The control unit 0 may be similar to that shown in Fig. 2 except that the electro-magnet R. is not selfinterrupting and is connected to ground, that the armatures associated with contacts al and bl are connected together and through a unilaterally conducting element Q1 and generator GeZ to ground, and that the lead connected to the electro-magnet R is also connected to the work contact z'l of a relay I, the associated armature being connected through 'a battery Ui to ground.

It will be assumed, by way of example, that one has to direct selector S to position 23. When said selector is connected to director or control unit 0, the following circuit is completed: ground, drive electro-magnet R of selector S, contacts s02,

'rest contact al, associated with relay A, unilaterally conducting element Q1, generator GeZ, ground. When the selector reaches the first-position of the required ten, position 20, in the example under review, contact al opens. in Fa similar manner to that described in connection with Fig. 2, contact bl is not energized, and the selector stops. Thereupon the relay I is operated and released three times, in the example given, by means not shown, so as to cause contact il to close three times in succession, and three direct current impulses, supplied by battery Ul, are sent to electro-magnet R, causing it to move ahead to position 23. f

It is quite obvious that the devices described above have been given only by way of example and that it would be possible, without thereby exceeding the scope of the invention, to increase the number of the positions to which the selector can be directed, by the device of providing a greater number of batteries, and a whole range of alternating currents differing from oneanother by their amplitude, their frequency or their phase g I claim: 1. In a selector system, a selector switch comprising a test wiper, a plurality of test terminals, and electric driving means for said switch, a plurality of potential sources connected to said test terminals, a first test relay. having contacts in the circuit of said switch driving means and adapted to operate at a predetermined voltage, a second test relay having contacts in the circuit of said switch driving means and adapted to :cperate' ata predetermined diiferent .voltage, the saidrelay contacts being arranged so that the voperationaof one .of: saidrelays without the other willdeeenergise the :switch sdriving means, while :then operation...of. both relays will not break the .icircuitfofsaid switch driving means, and marking .meansincludinga pair .of..contacts .for each test terminal-10f said switch .and unidirectional current devices formarking a position of the .switch IOISBIECtiOIL'thE windings of said relays and said :marking means being. serially connected between saidztest wiper. and saidrpotential' sources, the

-'connection-between.said'marking means and said sources being over a lesser number of leads than there, are test terminals.

2. In a selector system, the combination according 1170 claim 1, in which there are two uni- =.dir'ectional devices, one; connected in series with certainwof said marking contacts and the other connected in a reverse direction in series with.

certain other-ofsaid marking contacts.

, 3.;In1a selector system; acombination accord- -:ing.;. to..claim: -2 in: which the sources of potential are *connectedtogether-in series.

-4..In.ia selector. system, -.the combination ac-.

cording tozclaimfl, in.which the markingmeans is .:connected' :by: at least-"one lead to a junction point-between two ofsaid sources.

5.-In a selector system, the combination according to claim 1, in which there are two unidirectional devices, one connected inseries with certain of said marking contacts and the other connected :a reversedirection in series with .certainother of said marking contacts, and in which-said sources of potential are. connected togetherain series and certain .of said marking contacts are connected to the .junctionpoint he- .tweentwo of -saidsources while certainwother-of said marking contacts'are connected-toztheijuncation-qpoints .between others. of said-z-potential'.

sources;-

-6. In aselectorv system the combination .ac-

cording-to. claim-'1, ,in which two" unidirectional devices are providedoneconnectedin series with certainpf saidmarking contacts and the other connected in the .reverse direction :in series with certain. other ofrsaid. marking contacts, said potential sources being. connected together in. series, =and:.in.-.which saidtestrelays'are each provided with; two windings, certain of said marking contacts .being arranged to connect one. winding of each relay in series :while certain other of said :inarking contacts :being arranged to connect all oi-saidwindings in series, there. being 'a single wire connecting said marking contacts'with a junction point between two of said potential sources and in which additionalmarking contacts are provided forreversing the operation of said relayswith respect to said switchdriving 7. Inaa selectorsystem, the combinationaccording toclaim 1 in which the potentialsources .are all connected toma common point, and .in

which; two unidirectional devices are provided,

one connected in series with certain of said mark- .ing contacts andthe other connected in the-0pposite direction with certain other of saidmarking contacts, and in which the test relays are each provided with two windings, the connections being such that certainof said marking contacts connect one winding of each relay in series while certain otherof said marking contacts connect all of said windingsinseries, there being a single connection between said common point and said marking contacts, and .in .whichiadditional marking' contacts are provided toreverse the operation of saidtest relays with respect to said switch driving means, and in which .is provided a plurality of potential sources having different characteristics from said first-mentioned potential sources, certain of said test terminals being connected to one of said first potential sources and one of said second potential sources in series, a third test relay connected between said test wiper and the common point on said first potential sources, said relay being under control of said first and second test relays, means for making said third test relay responsive only to one of tional controlling means is provided responsive only to said alternating current sources for further controlling the switch driving means whereby the number of test terminals may be increased.

9. In a selector system, the combination according to claim 1 in which a third relay is provided under the control of the first and second test relays for performing an operation when the selector switch comes to rest at the desired position.

10. In a selector system, the combination according to claim 1, in which the connections between the sources of potential and the test terminals and the connections between the relays and the marking contacts are such that neither 'of said relays is operated when the wiper of the selector switch is on a test contact immediately preceding the marked position.

FERNAND PIERRE GOHOREL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name. Date :Re 22,799. iDeakin. Oct. 1, 1946 2,376,346 De akin; -May 22, 1945 2,423,078 Vriendt July .1, 1947 2,424,585 Simon July 29, 1947

Images