US1576723A - Wire chief's test circuits for telephone systems - Google Patents

Description

March 16 1926.

T. F. CROCKER WIRE CHIEF'S TEST CIRCUITS FOR TELEPHONE SYSTEMS 5 Sheets-Sheet l Filed July 28, 1922 TWIIE.,

,Thames Bracke? -Z- 2.4, 3U-3f- I March 16 1926.

T. F. cRocKER .WIRE GHIEFS TEST CIRCUITS FORTELEPHONE SYSTEMS Filed July 28, 1922 3 Sheets-Sheet 2 HIT- *Imi-nf?- Thnmasfranken March 16 1926.

T. F. CROCKER vWIRE CHIEFS TEST CIRCUITS FOR ,TELEPHONE SYSTEMS Filed July 28, 1922 3 Sheets-Sheet 5 lll *will Imran DI" Thames F. Eruker Patented Mar. 16, 1926.

-UNITE STATE.

THOMAS F. CROCKER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MES TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORI WARE.

Nn ASSIGNMENTS, oRArIoN or DELA- WIRE CHIEFS TEST CIRCUITS FOR TELEPHONE SYSTEMS.

Application filed July 28, 1922.

To all whom. t may concern.'

Be .it known that I, THOMAS F. Cnooiiuiz, L citizen of the United States of America, and a resident of Chicago, Cook County, and State of Illinois, have invented certain new and useful Improvements in IVire Chiefs Test Circuits for Telephone Systems, of which the following isa speciiication.

rFhe present invention relates in general Ito wire chiefs test circuits for telephone systems, but more especially to test circuits of this kind which are adapted for use in automatic telephone systems; and the object of the invention, briefiy stated, is revi sion and rearrangement of the circuits and the addition of certain new features, whereby certain desirable tests heretofore not provided for can now be performed accurately` and with the maximum facility. The apparatus employed, and the various features of the invention. will be described fully hereinafter, reference being had to the accompanying drawings, in which the system` is illustrated by means of the usual circuit diagrams.

Referring to the drawings, in oi'der to enable the circuits to be readily understood, the three sheets should be ai'ranged from left to right in proper alignment with each other. Then laid out in lthis manner, it will be perceived that Fig. l shows the test cii'- cuits proper, together with the necessary auxiliary apparatus, which is located at the wire chiefs desk; while Figs. 2 and 3 show the circuits of three automatic switches known respectively as a' test distributor, a test connector selector, and a test connector, which are used for connecting the test circuit to any subscribers line which it is desired to test.

To provide -for connecting the test circuits with subscribers lines which 'it is desired to test,r the wire chiefs position is equipped with a number' 0f outgoing test distributor connecting keys such as the key TDC, to which the test circuit shown in Fig.

l is connected in multiple, there being one key TDC for each test distributor l) accessible to the wire chiefs position. The test distributor D is a vertical and rotary switch of the well-known Strowger type, having Serial No. 578,174.

100'sets of bank contacts arrangedv inv ten horizontal rows or levels. In addition to the usual operating magnets and controlling relays, the switch is provided with a side switch controlled by the well-known private magnet, which is for the purpose of altering the circuits' aftei' each series of controlling impulses. is received. The switch circuits are'shown complete, and will be described in full hereinafter.

The test connector selector switch E, Fig. 3, is also of the Strowger` type, but differs from the test distributor D principally in having only'a single level of bank contacts. Itwill be understood from this that the switch has a rotary movement only, and that the vertical magnet and those parts which have to do only with the vertical movement of the switch'may'be omitted. It may be mentioned also that the off normal spring 113 is arranged so that it will nbe shifted on the first rotary step of the switch rather than on a vertical step, as is usually the case. The. test connector H is also a Strowger vertical and rotary switch, has the full 100 contact sets, and so far as its mechanical construction is concerned is similar to the test distributor D. The'side'switch is omitted, however, and lthe circuits are very much simplified in accordance with the simpler functions which the switch has to perform. The rectangle H indicates a test connector similar to H.

It will be understood .that the subscribers linesl in the systemare divided into `groups of .100 lines each in accordance with the capacity of the connector switches which are ordinarily used for completing local connections. In every 10() line unit, in addition to the 10 or 12 local connectors which are. ordinarily provided, there vis lone test connector such as the test connector H, the latter connect-or switch being exclusively for the use of the wire chief in testing the subscribers lines.' One of the subscribers lines of the group, to which the connector H belongs, -is shown at the extreme right of Fig. 3, and extends to the automatic telephone substation A. The reference character C indicates an individual line switch of the well-known rotary type, which is provided for the use of the subscriber at substation A in extending ioo Cil

the test switches will now be explained a little more l'ully. It we assume a i dig` system of 10,000 lines capacity, there wi be 100 groups of connector switches, am as a test conn ctor is provided in cach or these groups there will be 100 test connectors. New, since the test distributors hare 100 contact sets and are directively controlled in both their vertical and rotary inoven'ients, all of these test connectors may be reached by way of the test distributors without any intervening switches. This is the usual arrangement tor a straight i digit syst-ein. There will be perhaps three or tour ot the test distributors such as the test distributor D, Fig. 2, which have commen access to all of the test connectors in the various groups. It happens quite often, however. that in systems which include a number et party lines, in addition to the indiridual or private lines, third selectors are inserted between the second selectors and connectors in those major groups of the system which are used ttor the party line trallic. The party line subscribers are then calledv means of live digits, instead ot Atour, the extra digit being the third which controls the operation of the third selectors in selecting the proper group of connectors. The drawing shows an arrangement ot test switches which is adapted for use in a coinposite system of the type described, which includes both individual and party lines. The test distributors have direct access to all of the test connectors, such as H1, lt 3, which are located in the individual line connector groups, but on the particular level, or possibly levels, which are assigned to 'the party lines, the test distributors have access to test connector selectors such as the test connector selector E. lt is noted in this connection that the contacts in the party line level are not niultipled between several test distributors, but a trunk line erztends from each contact set to a separate connector selector. For instance, considering the `first contact set in the eighth level, it this Contact set corresponds to a paid;v line group, which we may assume tc be the case, it is not Inultipled between the several test distributors but a separate trunk .line extends from this contact'set in each test distributor to a different test connectanselector. lThe test connecter' selectors which correspond to the` same numbered contact sets in the test distributors have their banl; connect-ed in multiple and have common access to the test connectors in ten diterent connector groups.

A general description having been ven, the operation ot the circuits will now be Ltr/aves explained more in detail, and a description will be given of the procedure tollfiwe-il in connecting the test circuit with a subscriber`s line. Assuming that it is desired to test the line of substation A, Fig. 3, the teleplien number of which is 45678, the wire chieL iirst operates the calling dericc hey Cl). and the key Til@ associated with the i distributor Fig. 2, assuming that thisl particular rest distributor is the one wlf.1 is to be used. llllhen the calling device hey is operated, the calling device lil, Fig. l. i connected across the conductors ll and l2 ot the test circuit, and since these conductors have been extended to the operating conductors i3 and i4; et the test trunk by operation ot the key TDC., the relai 33, and 2T of the test distributor D energized in series over a circuit which may be traced from ground, winding of relay 2T, winding of relays 33, lower break springs ot' relay 30, conductor 14;, contacts ot 'lllll key. resistaiu'c 2`i8, upper winding ci po"- inet relay 202. centr-.cts o? conncf'tor key, Gl). heg', calling device l. bach llfrenga'i contacts olf' the GD. key, B. key, lilllffi. key, TQDC. key, conductor 13, upperl bi'cal; contacts ot relay 30, winding of relay 3l. to

battery. The relay 3l in oper-ath g closes a circuit 'tor the slow acng release rel 32, which, upon energizing, breaks i lease circuit at its armature '5l-3 and a saine armature prepares a circuit for vertical magnet il in the usual nient .it will be noticed that the upper windi oi the electro-polarized relay 202 is incl ded in series with the conductor Mr ot the line the test circuit. Relay 202 is not operated, however, since a circuit has alreary been closed at the T.D.C. key for its lower polarizing winding. The two windings are so connected that at this time their magnetisin?,- el'ccts oppose each other and the r y accordingly remains inoperative.

rilhe czftlling device dial may new bc operated in accordance with the tirst d" t olf the desired number, which is the dig t Y .ais a result a series ot tour interruptions is produced in the circuit ot relays 3l, Bil, and 2l', and all ot these relays accordingly deenergize n'iomentariiy lour times. llela, y each deenergization, transmits 'uni of current to the vertical magnet 4l over a path which may be traced 'trom gripiund by way of armature :'30 and its resting Contact, armature 52 and its wf; hing contact, the winding of the slow acting series relay ill, winding ot' the `vertical magnet ll, and the side switch wiper d3, in lirst position, to battery. By the operation of the vrti'al magnet, the switch wipers T0-T5, inclusive, are raised step by step until they stand opposite the fourth level ot banl: contee: Relay lll is energized in series with the rertical magnet, and being slow acting retains vate magnet 39.`

latter magnet adJusts the escapement in its armature in operated position throughout the vvert-ical movement of the switch. .ln its voperated. position relay 34 closes circuits for the slow acting relay 36 and for the. private magnet 39, which is also slow acting. The energization of relay 36 is without function at this time, but the private magnet controls the usual escapement mechanism by means of which the side switch is prepared for its advance to second position. At the end oi the vertical 'movement et the switch, the slow acting relay 'falls back and breaks the circuits ot relay and the private magnet 39. Upon the deenergization of the latter, the side switch wipers 42 and 4.3 are advanced te their second positions by the operation ot the escapemcnt.

The dial oit the calling device S may now be operated in accordance with the second digit ot the desirednumber, which is the digit 5. As before, a. sci-ies of interruptions is produced in the circuit of relays 3l, 33, and 27, and these relays are accordingly dc- .cnergized intermittently live times. Re-

lay 31 now sends a series et impulses to the rotary magnet l() over a path which extends trom ground by way oi armature 50 and its restingcontaet, armature 53 and its working contact, winding oft' relay 34, resting contact of armature 58 and the said armature, winding of the rotary magnet 40 and t-he side switch wiper 43, in second position, to battery. By the operation of the rotary magnet, the wipers -75, inclusive, are rotated step by step and are finally brought to rest in engagement with the particular contact set which corresponds to the desiredV major, or thousands, groupof lines. This contact set is assumed to be the one shown in the drawing comprising bank Acontacts 7 6-81, inclusive. The slow acting relay 34: is energized in series with the rotary magnet 4:0 the sameas in the previous case and closes circuits for relay 86 and for the pri- The energization of the readiness to permit the said switch wipers to pass-to third position when it deenergizes. At the end ot the rotary movement of the switch, the slow and breaks the circuit of the private magnet which thereupon deenergizes also and permits the side switch wipers to `pass to their third position.

The operations described at the end of the preceding paragraph invariably result when a party line number is called, because oty the fact that the set of bank contacts in the test distributor, which is connected with, has its own test connector selector individual to it,l and hence this set et cont-acts cannot be busy. However, in case a private or individual line number is called, in which case the test connector required is reached directacting relay 34 deenergizes ly by way of the test distributor, it may be that such test connector is busy and in such case it is necessary' to prevent the seizure et the connector at the test-distributor and to give the calling Wire chief a busy signal. It will be convenient to explain these operations. Now, it' we assume, for example, that the trunk line sho-wn at the right oi Fig. 2 extending to the test connector H is connected with, rather than the trunk to the test connector selector E, and it we assume furthermore that this test connector is there will be a ground potential on the test contact 79. Under these circumstances, when the slow acting relay Si falls back after the rotary movement ont the switch is completed, a locking circuit is closed ttor the private magnet 39, which entends Yfrom the grounded test contact 79" by way oi 'the test wiper 7 3, side switch wiper 4t2, in second position, the lower winding ot' the test relay 35, normally closed contact springs controlled by armature 56, and the winding o't' the private magnet 39 to battery. The private magnet is thus locked in energized position and prevents the side switch wipers from going to their third position. The heavy test conductors 82 and 83 are also held open at Contact springs controlled by the private magnet, and are thus kept disconnected from the wipers 70 and 75. rlhe test relay 35 is energized in series with the privatemagnet. This relay opens the rotary magnet circuit at its armature 58, and at its armature 59 connects a lead from Ythe busy signalling machine to the lower side et 'the test trunk, thereby placing anaudible busy signal. upon the line which will be heard by the wire chief, and which' will indicate to him that he has encountered a busy test connector. At the same time relay 35 closes a circuit at its armature 57 for the reversing relay 30 which, upon operating, reverses the conductors 13 and llt of the test trunk as regards their connections to the windings oi relays 3l, 33, and 27. By this opera-tion, the direction of current flow in the lower winding ofthe electropolarized relay 202 is reversed, and the said relay is accordingly operated te close aV circuitthrough the lamp L to battery. The lighting of the lamp L at this stage ot the operation gives the wire chie't a visual busy signal, supplementingthe audible signal. He may now follow either of two courses, that is, he may release the connection by restoring the T.D.C. key to normal, in whichcase the test distributor is restored to normal as will be explained subsequently, or he may leave the connection up until the desired test connector shall have become idle. Assuming' the latter course 1s followed, when the test connector is treed, ground is removed from test contact 79 and the circuit by which the' test relay 35 and private magnet 39 are be'- busy,

llO

CII

ing held energized is broken. The private magnet accordingly deenergizes, closes the heavy test conductors through to the wipers, and permits the side switch wipers to pass to third position, and when the test relay 35 deenergizes it disconnects the audible busy signal, and also breaks the circuit ot the reversing rel 30. Upon the deenergization ot this relay, the di v ion ot current flow in the conductors or tne test trunk is restored to normal, and the electropolarized relay 202 .is caused to retract its armature and extinguish the lamp li. ylhis notities the wire chie't that the desired test connector is now available and has been con nected with, and he may, therefore, proceed to call ldie remaining' digits.

i1 tter this digression we will now return to the establishment ot' the connection under consideration, and explain its further progress. By the operation o't the test dis tributor which has been described, the connection has been extended through as 'tar as the test connector .selector ll, Fig. 3. 1When the. side switch wiper 4? ot the est distributor reaches its third position, a circ-uit is closed for relay 3i', which encre-nies and extends the operati] circuit through to 'the relay 3S in order to provide tor turther encrldictation oit the slow acting` relay 3st, and at the same time relay 37 prepares a point in the circuit ot the test wiper T2, and also closes a bridge across the. wipers 71 and 74 at armature 63. By the latter operation a circuit is completed tor the windings ot the line relay 100 ot the test connector selector l, and the said relay is accordingly ener- `ized and completes a circuit for the slow act-ing release relay 101. Upon energizing in turn, relay 101 connects ground to the 'release trunk conductor 85, whereby the connector selector l is made busy. Relay 101 also opens a point in the circ-uit of the release magnet G at its armature 112, and aty the same armature prepares a circuit for the rotary magnet 105, lt will be queried why it is necessary to ground the test contact T9 to mal-:e the test connector selector E busy, inasmuch as according to the previous explanation of the trunkinp; arrangement, the test distrilnitor D is the only switch which has access to the test connector selec-V tor lll. This is a pertinent question and the answer is `that it the trunking; is arranged as described,y there is no particular utility in grounding' the test contact T) when the 'est connector selector is taken ior use. Tho provisions tor `arounding` this test contact cause no harm, however, and they render it possible to use switches such as the test connector selector E in alternative trunking arrangements without change. For instance, when the testing' facilities are increased, the number ot test distributors D will increase faster than the number of test connector selectors in any one group. Thus, the number ot test connector selectors need not exceed three no matter what size the system is, loutit is conceivable that the number of test dl 'ibutors might be increased to six or even more. In such case there would be two test distributors having` access to each ot the three test connector selectors in cach group.

rl`he wire chief may now operate the dial o't the calling device S in accordance with the third digit ot the desired number, and as a result, another series ot interruptions are produced in the circ-uit ot relays 31, 33, and 27 ot the test distributor l). As betere, the relay 3l. sends an impulse ot current, at each deenergiization, through the slow acting series relay v, and the said relay is energized and remains in operated position throughout the transn'iission ot the third series oi" impulses, tho same as it did during,` thc transmission ot the tirst and second series. Since this circuit is completed by way ot the relay however, no lurther mechanical operation ot the test d islrihutor l) will take place, but relays 36, 38, and the private magnet 39 are operated nevertheless, and the latter opens the test conductors 82 and 83 while the impulses are being' received. It will be noticed that the bridge across the wipers 71 and Tet which was closed at armature 63 ot' relay 37 includes also the armature 51 of relay 31, and it follows, therefore, that each time relay 31 deenergizes, it will open the bridge to cause the deenergization ot the line relay 100 ot the test connector selector E. lt will be seen then that the test distributor l) operates as a repeater after it has itself been operated to repeat impulses to the next switch taken tor use, which in this case is the aforesaid test connector selector E.

The operation ot this switch may now be described. At each deenergization of the line relay 100, responsive to the impulses which are peated from the test distributor l), an impulse ot' current is transmitted to the rotary magnetl 105 over a path which extends from ground by way of armature 109 and its resting contact, armature 112 and its workin contact, windingr ot the slow acting` series relay 102, armature 116 and its resting contact, winding; ot the rotary magnet 105, and side switch wiper 108, in its tirst position, to lv attery. By the operation ot the rotary magnet 105, the wipers 130135, inclusive, are rotated step by step and are stopped in engagement with the particular set ot contacts in which is terminated the trunk line which extends to the test connector in the desired hundred line group. This trunk line is assumed to be the line shown in the drawing, which terminates in bank contacts 136- 141, inclusive, and extends to the test conn nector I-I. The slow acting relay 102 is energized in series with the rotary magnet 105 and remains in operated position throughout the rotary movement of the switch, At its armature 114, relay 102 closes Va circ-uit for the private magnet 104 which is energized and adjusts the escapement to permit the subsequent release oi the side switch. At the end of therotary movement, relay 102 falls back and breaks the circuit o1 the private magnet 104. l/Vhether or not the private magnet will be energized at this time depends upon whether or not the test connector H is busy. Assuming rst that the connector is busy, there will be a ground potential upon the test contact 139 and whenV relay 102 deenergizes, a locking circuit will be established which extends trom ground on the test contact 139 'by way of the test wiper. 133, side switch wiper 107, in first position,winding of test relay 10? normally closed contact springs controlled by armature 114, and the winding of private magnet 104 to battery. Since this locking circuit includes the winding of the test relay, this relay .is energizedV in series with the `Di'ivate niaOnet. At its armature 115 and 11S, test relay 103 opens the heavy test conductors 82 and 83, at its armature 116 it breaks the rotary magnet circuit, and at its armature 117 the conductor 35 is disconnectedA from ground and is connected instead through a low resistance tothe ungrounded pole ot the battery. By the lat-ter operation a. circuit is completed by way oit the said conductor 85, test contact 79, test wiper T3, side switch Wiper 42, in third position, and the upper winding of the test relay 35 to ground. Test relay 35 is accordingly energized and at its armature 59 places an audible busy signal on the line in the direction ot the wire cliiets test board. rit the same time, at armature 5l' a circuit is completed ior the 'reversing relay 30, which opera-tes to reverse the' direction of current How in the lower winding of the elec-tropolarized relay 202 at the test circuit and thus gives the wire chi-ef a visual busy signal by lightingrthe lamp L. The wire chief may disconnect at once, or he may wait on t-he line until the test connector H is cleared and becomes available for use. Vhen this occurs, ground is disconnected from the test contact 139, the test relay 103, and the private magnet 104 of the test connector selector E are deenergized, and the said test relay breaks the circuit of the test relay 35 in the test distributcr D. Relay 35 then drops back, removes the audible busy signal lrom the line and breaks the circuit of relay 30. The deenergizatioii of the latter relay then reverses the direction of current how in the circuit ott the electropolarized relay 202 back to normal, and thus causes the lamp L to be extinguislied.

Returning` to the test connector selector E,

when the private magnet 104 deenergizes,

either on the breaking ot its linitial energiz ing circuit at relay 102, or upon the breaking of its lockingl circuit when the selected test connector is :tound to be busy and eventually becomes idle, a bridge is closed across wipers 131 and 134 at armature 120. Thisi operation completes a circuit in an obvious manner for the double wound line relay 150 l The. dial of the calling device S now` be operated in accordance with the next vdigproduced in the circuit of relays 31, 33, and 27 at the test distributor D, and theseinterruptions are repeated by relay 31 into the circuit of relay 100 of the test connector se.- lecto-r E. Responsive to the interruptions ot its circuit, relay 100 then operates to repeat a like series of interrupt-ions into the circuit ot' the line relay 150 ot the connector? lll, the bridge across the wipe-rs 131 and 134 being opened at armature 110 every time relay 100 falls back. In response to the interruptions thus produced in its circuit, relay 150is deenergized momentarily seven times `and at eacli deenergizationtransmits a current impulse to the vertical magnet 154 over a path which may be traced from ground by way of armature 160 and its resting contact, armature 162 and its working contact, opti normal springs 157 andl 15,9, winding oi slow acting series relay 152, and the winding of the vertical magnet 154 to battery. By the operation of the vertical magnet 154, wipers 170-172, inclusive, are raised step by step and are brought to rest opposite the seventh level of bank contacts. Relay 152 is energized in series with the vertical magnet, and being slowY acting, remains in operated position throughout the vertical movement of the switch. VThe operation oi' this relay is effective to maintain the vertical magnet circuit closed notwithstanding the fact that theoii" normal springs 15T-159, inclusive, are shifted., whiclioccurs at the iirst upward movement of the switch shaft. At the end of the vertical movement -ot the switch, relay 152 falls back and transfers the operating circuit to the rotary mag` net 155.

The calling device may now be operated for the final digit in the desired number, which is the digit 8. A series of eight init in the desired number, which .is the digitl i. As a result of the operation of the calling device, a series of seven interruptions are,

terruptions is thus produced in the circuit of relays 31, 33, and 27 of the test distributor D, and these interruptions are repeated as before into the circuit of relay 100, of the test connector selector E, which in turn operates to repeat them into the circuit of the line relay 150 at the test connector H. Belay 150 is, therefore, again deenergized momentarily a plurality of times and sends a series of impulses to the rotary magnet 15d over a circuit which extends from ground by way of armature 160 and its resting contact, armature 162 and its working contact, off normal springs 157 and 15S, armature 163 and its resting contact, winding of the slow acting relay 153, and the winding ofthe rotary magnet 155 to battery. By the operation of the rotary magnet wipers 170-172, inclusive, are rotated step by step and are finally brought to rest in engagement with the particular set of bank contacts in which is terminated the line of substation A, these bank contacts being .inuicated in the drawing by reference character 173175, inclu sive. Relay 153 is energized in series with the rotary magnet 155, and being slow acting, retains its armatures 164: and 165 tracted during the rotary movement and thus disconnects the wipers 170 and 172 until the switch is finished operating, when it falls back and again connects up the wipers to the heavy testing conductors.

Further operations at this'stage depend upon whether or not the line of substation A is busy or idle. It will be recalled that the circuit of the test distributor D is such that after this switch has been operated, the line relay 31 continues to send impulses to the slow acting relay 34 at the same time that it repeats impulses to the switches beyond. Thus, the said relay 34 is energized not only responsive to a series of impulses intended to operate the test distributor D, but also to the several series of impulses which operate the test connector selector E and the test connector H. It will be evident also that whenever relay 34 pulls up, circuits are closed for the slow acting relay 36 and the private magnet 39. lith these facts in mind, the operations which take place, if the called line is busy, will be readily understood.

If the line is busy when connection is established therewith by means of the test connector H, as explained in the foregoing, the test wiper 171 will find a ground potential on the test contact 1711- and when the slow acting relay 3% in the test distributor D falls back at the end of the final series of impulses, a circuit is completed for the reversing relay 30, which may be traced from the grounded test contact 174e by way of test wiper 171, conductor 169, test contact 138, test wiper 132, armature 119 and its resting contact, conductor 84, test contact 7S, est

wiper 72, working contact of armature 54 and said armature, armature 55 and its resting contact, working contact of armature 62 and the said armature, armature and its working contact (slow acting relay 36 being still in energized position), and the winding of the reversing' relay 30 to battery. Upon energizing, relay 30 closes a branch of the above traced circuit which extends from armature 62 by way of the working contact of armature 65 and the said armature, armature 61 and its working contact, and the winding of the slow acting relay 36 to battery. It may be explained that relay 30 pulls up and closes this branch circuit before the slow acting relay 36 has had time to deenergize followingthe breaking of its initial energizing circuit by the falling back of slow acting relay 34, and re lays 30 and 36 are thus both held in operated position by the ground on the test contact 1% of the busy called line. Then relay 30 operates to reverse the direction of current flow in the upper winding of the electropolarized relay 202 in the test circuit in the usual manner and this relay is, therefore, operated to light the lamp L and thus give the wire chief the visual busy signal. It will be noticed, however, that no audible busy signal is in this case placed on the line, and indeed it would not be practical to do this inasmuch as the heavy test conductors are now actually connected with the two line conductors of the called line. Furthermore, the audible busy signal is unnecessary because the wire chiefs head set is connected across the test conductors in series with the calling device, and by listening on the line he can at once ascertain whether it is engaged or not.

Finding that a conversation is going on, the wire chief may, of course, release the connection and try the number again later en, or he may restore the calling device ley C D. in order to leave the connection under the control of the electropolarized relay 202. If this latter course is followed, it will be evident that when the called line becomes idle and ground is removed from the test contact 174, the circuit of relays 30 and 36 of the test distributor D will be broken, and the former relay, upon deenergizing, will reverse the direction of current flow in the lower winding of relay 202 back to its normal direction of fiow. Relay 202 is thus caused to deenergize and lamp L is extinguished, the wire chief being notified by this operation that the called line has become idle.

Having explained the operations which take place when the called line is busy, we will now consider' what occurs when the line is idle, it being immaterial whether we consider that the line is idle when called, or becomes so some time after the connection has been established. In either case, when the slow acting relay 36 of the test distributor l) .falls back, a circuit is completed which extends from ground by way of the resting contact ot armature 60 and the said armature, armature 62 and its working Contact, resting contact of armature 55 and the said armature, armature 54 andi its working contact, test wiper 72, test yContact 78, conductor 84, resting contact of armature 119 and said armature, test wiper 132, test contact 138, conductor 169,`test wiper 171, test contact 174, private normal conductor 177, winding ot' the cut off relay 179, and the winding of the rotary or stepping magnet 180 of the line switch C to battery. By the closure of the above circuit, a ground potential is placed on the test contact 174 to make the line busy in the usual manner, and at the same time relay 179 is energized and clears the line o1 substation A of its normal battery and ground connections in the line switch C. It may he explained at this time that relay 179 is operated only about halr` way because of a mechanical locking device controlled by the line relay 181, and the wipers of the line switch are not connected Having completed the connection to the` line which is is desired to test, the wire chief may now restore the calling device key CD, thereby disconnecting t-he calling device S from the operating circuit and again closing the operating conductors. 1t

opens the two sides of the test circuit and' connects a ringing current generator in bridge thereof in the usual manner. The listening key is now thrown and also the battery feed keyBF. By the operation of the listening key, the wire chiefs headset is connected across the heavy lined test conductors of the test circuit in series with the condenser 215, while the listening key and the BF key together connect the battery feed coils 20G and 207 across the test conductors, in order to supply talking currest to the transmitter at the subscribers telephone.

It' it is desired to release the entire connection without disconnecting the test circuit from the outgoing test trunk, the release key is operated for a short interval. This opens the energizing circuit for relays 31, 33, and 27 in the test distributor D. Assuming now that all the other keys inthe test circuit are in normal position, there will be no circuit closed to maintain the said relays 31 and 33 energized and they vwill tall back. Relay 31 breaks the operating circuit extending to the test connector selector E, and also breaks the circuit of vthe slow actingrelease relay 32. When the latter relay falls back, itl closes a circuit for the release magnet 44 which restores theV test distributor D to normal position in the well-known manner. At the test connector selector E when the circuit! ot the line relay 100 is broken, this relay falls back and breaks the circuit oit the slow acting release relay 101, and, upon deenergizing, the latter relay closes the circuit of the release magnet 106. The operation of release magnet 106, ot course, restores the connector'selector E to normal also. The line relay 100, on deenergizing, breaks the Vcircuit of the line relay 150 of the test connector H, and this switchgis accordingly lrestored to normal by the operation ot release magnet 156, whose circuit is closed in an obvious manner by the joint action ot relays 150 and 151. Thus, all the testswitches in use are returned to normal position and are ready to be re operated to connect with the same or another line.- Y

Sometimes it is desirable to release the` test connector selector and the test connector without restoring the test distributor as, tor example, incase it is desired to test another line in the same group. This can be accomplished by the operation of the connector release key. lVhen this key :is-operated, the exchaiige battery is connected by way otl resistance 205'tlirough the upper winding ot polarized relay 202, resistance 208, contacts ot'lDC key, to the conductor 14 ot the test circuit, while at the same time the original operating loop for the relays 31, 33, and 27 ot' the test distributor D is opened at the break ot' contact-s of the connector release key. Since, the lower conductor ot' the operating circuit is now connected to the ungrounded pole of the battery, relays 33 and 27 will beheld energized, but the circuit for relay 31, being now open, that relay'will i'all back. Relays 33 and 27 hold the slow acting release. relay 32 energize-d in order to pr vent the release of the test distributor D, while relay 31 breaks the operating circuit of the test connector selector E, and there.- by causes the test connector selector and test connector to be released and restored to normal, las previously described. It will be ohserved that relay 31 closes a circuit through the slow acting relay 34, which in turn energizes, and closes a circuit tor the private magnet 39. The operation of the private magnet at this time opens the heavy testing conductors and'prevents the application of battery potential to other lines While the test connector selector E and the test connector ll are retur ing their Wipers to normal position.. 'the connector release key need be operated only for a briet interval, and atter it is restored to normal, the calling device key Cl) may be operated tor the purpose ot' connecting the calling device S across the test circuit to reoperatethe test connector selector and the same or unother test connector.

The HC@ key is provided to enable the wire chiot to deenergize the cut oli' relay oi a called line and perinit the testing of said linel in the direction oiI the automatic switchboard. Vilhen the BC@ key is operated, the conductor 'l2 is divided into tivo sec-tions and direct ground placed on the section which extends to the outgoing operating conductor 13, While the other section ei;- te'nds through the various test keys to corductor l-l, and is opened simultaneously by the operation ot the BCG key, causing relays and 2T ot the test distributor l) to deenergize. Relay 3l is maintained energized by ground extending trom the BC() key, while relays 33 and 27 are permitted to tall back. The deenergization ot' relay 27 disconnects at its armature Bil ground trom the test Wiper T2 ot the test distributor switch l), and thus breaks the circuit ot the cut otf relay 179 of the line switch U. l y means ot the volt milainmeter, the Wire chiel" may now test the two sides o'i'" the subscriber-"s line tor battery and ground, respectively, in a manner which will be explained subsequently.

'lhe standard routine tests for line troubles are performed in substantially the same manner as in ordinary p notice, ani hence will require only a cursory discussion. Considering first the method ot testing tor a short or a ground, with all the keys in the test circuit at normal, the volt milanimeta-r V and rheostat lt are connected in series with the conductors 9 and l0. The wire chiot proceeds by operating the test key l, which connects the volt milannneter V and the rheostat R, trom the line test conductor 82 ot' the test circuit to ground, in series with the l0() volt testing battery l. The circuit may be briefly traced troni the conductor S2 ot the testing circuit at the TDC, key, by way et contacts ot the TVT, key, contacts ot the ringing key, contacts ot the listening key, contacts ot the reversing key, contacts ot the test key K, noiv operated, through the volt inilannneter V and rheostat R, contacts ot the test key K, to the test battery B in series to ground. Ground is also connected to the line test conductor by the operation ot the key K. rlhis circuit may be briefly traced from ground, resistance K, contacts ot' Key l, contacts of the ground key, contacts ot' the listening key,

contacts ol the ringing key, contacts of the reversing key, contacts 'ot the TDC. key to conductor 83. Under the above described circuit conditions it will be seen that it there is a ground on conductor or it conductors 82 and 83 are crossed, or shorted tege: the needle oit the volt milanni'ieter uill he deflected. rlhe reverse key u'iay nouv be operated nwinentarily in order to determine Whether the delico-tion is due to a short or a ground on conductor S2. To test for a ground, the ground key may non' be operated, which removes ground on conductor titl trom conductor lli the Yvolt milanimeter needle remains deflected, it will indi cate that conductor 83 is grouudet.

lt desired, tests for foreign battery a be made by restoring the test key K, am by ope ating the ground Under the a `ove described conditions, a circuit is connA eted from ground at the ground key, contacts ot key lr, the volt iniiannneter V and rheostat lt, contacts of key K, through the previously traced key sets to test conductor 82, eX- tending to the upper conductor et the called line. li there any foreign battery on this conductor, the needle will be deff accordingly. A similar test may be made on test conductor 823 extending to the lower line conductor by operating the reversing key. f

ln case it is desired to test the adjustment ot the bridge cut oil relay lf' ot the subscribers individual lineswitch C (hereinatter reiter-red to as BC() relay 1.79), the Wire chieti operates the reversing key, and the third wire test key TVT. rlhe operation ot the key llVfl connects vthe conductor 13 direct to ground, and connects the conductor l-'l through a high resistance 20?" to battery. The line relay il o't` the lest distributor D is noiv maintained energized independent ot relays 33 and 2T, while the relays and Q7 receive current independent of relay 3l. Due to the high res 907', nd the high resistance ot rel as compared to that ot relay 27, the latter relay deenergizes at this time and at itsI armature 2G closes an operating circuit for relay 3S, Which now pulls up. The operation of relay 38 at its armature E25 disconnects the test conductor S3 from the wiper 75, and connects the saine 'to the test Wiper 72 leading to the BCO relay lift). lt will also be noted that the relay 2T in t u back, at its armature et disconnected the original holding ground from the wiger T2. Keeping in mind the tact that the keys T DC., TVl., and the reverse key ar now in operated position, a tes., circuit ttor the BCO relay 179 may new be traced from ground., Winding oit battery feed coil 20?.

luf)

through the volt meter V, rheostat lt,

through springs oit the battery test key l,

vegfras listening and ringing lj' eys, tl1e'V reversing key, in operated pos1t`1on,-through operated springs ot key TDC., conductor 83, lower restingcontact and armature of relay 39,'

chief may now proceed to' test the adjust-l ment of the bridge cut oil manipulating thel rheostatR, observing the volt niilanmeter needlev inthe meantime in order to determine the current value at which the BC() relay Will restore. y

As-suming,` that the adjustment vof BCO relay H9 by relay 179 is correct, the same will restore at the proper time, andI in' so doingiwillreconnect, at its Aupper armature andr'esting contact, `the line relay 181 `to the upper line conductor, thus closing a' circuit extending to conductor 82, keys? TDC. and' TV., through the Wire ehiets headset, back' to the TNT. key, Where l one branch' extending to conductor 83 land thence over the previously traced circuit to the BCO' relay 179, battery and' ground,

and the other branch `extending over the' preyicusly tracedv Circuit tothe battery feed' coil' 207 and ground. Ity Will be readily seen that when the above described circuit'i's" completed through the Wire chi'elfs headset, that a distinctive click Will be'hea'rd", indi-V eating that the BCO rel'ayhas' deen'ergiz'ed,y circuit in which the line relay 181 is included, thisV relayl Due to' the' high' resistance Will' not be operated, its'connectienin'multiple' Witlrthe BCOre'lay ufill,'howeyer, cause" an increased' flow of current through the volt milammeter which will further indicate to the Wire chief that the BCO; relay has deenergized. c y

If the'BCO relay fallsv backxbefore the 1rolt milannneter {aving described my invention, what" I' consider to be new and desire t' have pro-- tected by Lettersl Patent Will'b'e pointed out in the appendedclaims.v Y

1. Ina terlephone'system, a'ca'lhng line, a called"line,meansfincluding a seriesof automatic switches for extending aconnection to` said called line, testing` apparatus associated with saidca'lang line and including` a' test circuit', an automatic switchassociated withL said called line,"a'cutlotlrel'ay i`n said autothe: circuit divides,

.needle has been" deflected to a` predetermined point, -1t will indicate matic switch' operated' when a connectibni's extended to saidl line, aAt relay in a switch of said' series operable through the medium of said testingi apparatus to' cause said cut-oil' relay te be included in" said test circuit, and means'include'd in sa-idtesting apparatus forv varying at Will the current'low in said cut-olil relay.

Qiln a" telephone system, a calling line, a called line, means including a series of auto'- matic switches for extending a connection to' sai-d called line,` testing apparatus associated With said1 calling,` line and illicit-ming a test circuit, an automatic switch'` associatedl r-ithsaidV calledl line', a' cut-olfrel'ay in said automatic' switch ope ated when' a connec* tion is extended to said line', a relay in a switch oi said series operable through the medium ot said testing apparatus to cause said cut-otlI relay lt'obe included in said 'test circuit, means for Varying the current in. said circuit, and visual indicating means included'in said circuit' for determining the amount ofcurrcnt flowing.'

3l In a telephone'system,I a calling line, a called line', ineansincluding a' series o'auto-l matic' switches for extending connection' to said called` line, testingl apparatus associated with 'said' callingV line and including a test circuit', an' automatic switch associated with said called' line, a cut-cti relay in said automatic switch operatedv When a connection is extended to said line, relaywin a switch' of said series operable through the medium of said testing'` apparatus to` clause said cut-'odrelayl to be included in said' tes-t circuit, Va' rheostat included in said circuit` to' ca'use the current flow pto'V be yaried, andlananuneter included in said circuit tov indicate tl'ielcu'rrent valuel at any position oi' said'rheostat. l p y v t; Inl a telephone system, a calling line, a called line',meansincluding a series o't automatic switches for extendinga connectionto said called line, testing apparatus associated` with said daling linejand includingl a test circuit, air-automatic Yswitch associated with said' called line, a' cut-oill relay in said aut@ matic switch operated' when ai cennection is extended' tosaiidv line,a relay' in asufitch of said series operablev through' the medium cit saidl testingl apparatus to cause said cut-oli' relay tobe included in said test circuit, a rheostat included inv said circuit to' cause the current dow' t'o'pbe \f"ari'ed,an ammeter included in said circuit to'indicate the current value at any position of said rheostat, and means for' transmitting an audible signal over the' calling` line When the' current in' said circuit is reduced' s utliciently to cause said cut-oifrel'ay to' deen'ergize.

v 5. In' a telephoners'ystem, a test circuit in-` cludin'g a Itest conductnfmeans including any automatic directively' controlled' switch for `ILC) extending said test conductor into connec tion with one line conductor of a line to be tested, a cut-oiii relay for said line, a third conductor for said line connected with said relay, and means for shitting said test conductor from connection with said line conductor into connection with said third conductor.

6. In a telephone system, a test circuit including a test conductor, means including .an automatic directiyely controlled switch for extending said test conductor into connection with one line conductor of a line to be tested, a cut-oil1 relay tor said line, a third conductor for said line connected with said relay, wire chief-s testing apparatus including a key associated with said test circuit, and means responsive to the actuation oi said key ior shifting said test conductor from connection with said line conductor into connection with said third conductor to permit the testing of said relay.

7. In a telephone system, a test circuit including two test conductors, means including an automatic directively controlled switch for extending said conductors, respectively, into connection with the two line conductors ot a line to be tested, a cut-off delay for said line, a third conductor over which said relay is energized, and means :tor disconnecting` one ot said test conductors from the line conductor with which it is connected and for connecting it instead to said third conductor.

8. In a telephone system, a test circuit including two test conductors, means including an automatic directively controlled switch for extending said conductors, respectively, into connection with the two line conductors of a line to be tested, a third conductor over which said relay is energized, testing apparatus associated with said test circuit, and means for shitting one of said test conductors from the associated line conductor to said third conductor in order to test said cut-oil relay.

9. In a telephone system, a. test circuit including two test conductors, means including an automatic directively controlled switch for extending said conductors, respectively, into connection with the two line conductcrs of a line to be tested, a. cut-oil relay for said line, a third` conductor over which said relay is energized, and means for breaking the initial energizing circuit of said relay and for closing a new circuit for said relay including one ot said test conductors.

l0. In a telephone system, a` test circuit including two test conductors, means including an automatic directively controlled switch for extending said conductors, respectively, into connection with the two line conductors off a line to be tested, a cut-oil relay for said line, a third conductor oven which said relay is energized, means for irealring the initial energizing circuit ot said relay and for closing a new circuit for said relay including one of said test conductors, means for varying the resistance of said test conductor to cause said cut-ott relay to deenergize, and means for indicating the point at which deenergization takes place.

l1. The combination, with a wire chiefs test circuit, of means including an automatic directively contiolled switch ior connecting said test circuit with a line to be tested, means tor testing the two line conductors of said line, a cut-ofi relay and a third conductor for said line, and circuit arrangements whereby the means employed tor testing said line conductors may be used also tor testing` said relay over said third conductor.

l2. The combination, with a wire chielis test circuit, of means including an automatic directively controlled switch lor connecting said test circuit with a line to be tested, means for testing the two line conductors of said line, a. third cond actor individual to said line, and circuit arrangements where` by the means employed .tor testing said line conductors may be used also for testing said third conductor, independent of said line conductors.

13. The combination, with a wire chiefs test circuit, of means including an automatic directively controlled switch ior connecting said test circuit with a line to be tested, a test conductor extending from said test circuit to said switch, a second test conductor individual to said line, and means in said switch for connecting said first test conductor to a conductor of said line and to said second test conductor separately.

'14. The combination, with a wire chiefs test circuit, of a1 directively controlled automatic switch, a test conductor extending from said test circuit to said switch, a line including two line conductors and a third conductor, means including said automatic switch for connecting said test conductor to one of said line conductors, and means in said switch for disconnecting said test conductor from said line conductor and connecting said test conductor to said third conductor at will.

15. The combination, with a wire chiets test circuit, of a directively controlled automat-ic switch, two test conductors extending from said test circuit to said switch, a line including two line conductors and a third conductor, means including said automatic switch for connecting said test conductors to said line conductors, and means in said switch for disconnecting one of said test conductors from the corresponding line conductor and connecting such test conductor to said third conductor at will.

1G. The combination, with a wire chiefs SiO test circuit, of two testing conductors and it controlling conductor, zr line including tw@ line conductors and a third eonduetor, means for connecting` said test circuit With said.v 5 line conductors via said test conductors, and

ineens reinetel;7 controlled over said controlling' conductor for disconnecting one of Said test conduct-ors from theeorresponding line conductor and for connectingsuch test conductor to said third conductor at will. 10 In Witness Whe-reef, I hereunto subscribe my naine this 22d davy of July, A. D. 1922.

THOMAS F. CROCKER.

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