US2400530A

US2400530A - Selector switching system

Info

Publication number: US2400530A
Application number: US531949A
Authority: US
Inventors: John I Bellamy
Original assignee: Kellogg Switchboard and Supply Co
Current assignee: Kellogg Switchboard and Supply Co
Priority date: 1944-04-20
Filing date: 1944-04-20
Publication date: 1946-05-21
Anticipated expiration: 1963-05-21

Description

May 21, 1946. J. l. BELLAMY SELECTOR SWITCHING- SYSTEM Filed April 20, 1944 16 Sheets-Sheet 1 EN mi@ WNY.

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SELECTOR SWITCHING SYSTEM Filed April 2o, 1944 leshefs-sheet 15 N m l Eg? L y I- Il IT'Z IT fla E j ziz 16 Sheets-Sheet 16 J. l. BELLAMY SELECTOR swITCHING SYSTEM Filed April 20, 1944 1.702727] Ee] [am May 21, 1946.

Patented May 21, 1946 UNITED STATES lPATENT oFFlcE 2,400,530 SELECTOR swrromNG SYSTEM John I. Bellamy, Brookfield, Ill., assignor toA Kellogg Switchboard and Supply Company, Chicago, Ill., a corporation of Illinois Application April 20, 1944, Serial No. 531,949

41 Claims. (Cl. 179-18) This invention relates to selector switching systems, being concerned more particularly with selector switching systems employed at selector switching stages in automatic telephone systems and the like to interconnect any calling incoming trunk with an idle outgoing trunk in any called numerical group.

The general object of the invention is to provide an improved selector switching system of.

the type employing a group of tandem-related subgrouped primary and secondary switches.

GENERAL DESCRIPTION This invention is an improvement on the switching system employed at the selector switching stage disclosed in my prior application for Automatic telephone switches and systems, Serial Number 451,565, led July 20, 1942, now Patent No. 2,354,660, granted August 1, 1944. The principal feature of improvement over thesaid prior applicationis that the primary and secondary switches at a selector stage are more eiciently v Fig. 9 is a modification of the selector illustrated in Fig. 3; i I

Figs. 10 to 15 are drawings similar to Flgs.'3 to 8 respective1y, but .umstrating modined circuit arrangements for. use with a modified arrangement of the switching mechanism at the selector stage;

e "Fig, 16 shows the way Figs. 3 to 8 are intended to be assembled; and

Fig. 17 shows the way Figs. 10 to 15 are intended to be assembled. The primary and secondary switches employe in the selector system as disclosed herein may be of the general type disclosed in my prior appli,- cation hereinbefore referred to, vbut are illustrated as of the `twenty-point, three-wire, en-

A corresponding feature of the invention is that the actfof establishing a connection from a calling incoming trunk to an idle outgoing trunk in a called numerical group, while temporarily monopolizing the primary subgroup at which the calling incoming trunk terminates, and the secondary subgroup at which the said idle outgoing trunk terminates, leaves all other primary and secondary subgroups free to handleother calls.

THE DRAWINGs Other objects and features of the invention, for

the most part subordinate to those enumerated, will appear upon a further perusal of the specication in connection with the accompanying drawings comprising Figs; 1 to 17, wherein;

larged-capacity type disclosed in my application for Automatic telephone switches, Serial No. 524,816, led March 1, 1944. l

THE PRIMARY-SECONDARY ARRANGEMENT In the modication showny in Figs. 1 to 8, the primary and Secondary switches are arranged face-to-face at the selector stage, and interconnected by selector links. That is, each primary switch servesas the terminal point for an `incoming trunk, and has access (in common with other switches of the same primary subgroup) to twenty selector links, and each secondary switch serves as the beginning point of an outgoing trunk and has access (in common with the other Switches of the same secondary subgroup) to twenty selector links.

This arrangement is illustrated best in Fig. 2 wherein nine primary subgroups of switches, A to I, are indicated and nine secondary subgroups of switches A to I, lare indicated. Primary subgroups C to H and secondary subgroups C to H are omitted from the drawing for the vsake of simplicity and to conserve drawing space. Since each subgroup of primary or secondary switches may have access to twenty 'A selector links, the number of selector links is twenty times the number of primary or ySecondary subgroups. In the illustrative example, the nine primary and nine secondary subgroups (A to I) provide for a total of 180 selector links. In this arrangement, the number of selector links may y vary from forty to four hundred, according to Fig. 1 is a .call-through diagramshowing a connection completed from theV calling line to a called line by way of a selector stage employing a selector system according to the invention;

Fig. 2 is a schematic trunking diagram illustrating the general arrangement of one embodiment 'of the improved selector system; 1

f Figs. 3 to 8 are circuit drawings of portions of the equipment indicated in Fig. 2;

Athe traic to be carried by the primary-secondary group.of switches, for the number of subgroups can vary from two to twenty.

The number of primary orsecondary switches .in a subgroup has more or lessfarbitrarily been set at fifteen. By this arrangement, only ilfteen of the twenty selector links served by a primary or a secondary subgroup can be in use at the hsame time, whereby the selector links areoperated at a very low traffic density and a consequently low lost-call rate', which, is in keeping with their comparative low cost.

In Fig. 2, the primary switches are represented by horizontal lines PAI to PAI 5 -for primary subgroup A, PBI to PBI5 for primary subgroup B, and PII to PII5 for primary subgroup I. The secondary switches are represented by horizontal lines SAI to SAI5 for secondary subgroup A, SBI to SBI5 for secondary subgroup B, and SII to SII5 for secondary subgroup I. The vertical lines extending across a subgroup represent the twenty link outlets of the subgroup by way of the twenty contact sets of any switch in such subgroup. The common outlet (or inlet) terminals of ra subgroup are shown at the top, numbered I to 20. A few of the 180 selector links are shown interconnecting primary-subgroup terminalsl with secondary-subgroup terminals. t

The nine primary subgroups, A to I, of Fig. 2, with fifteen primary trunks each serve as' termimating points forf135 incoming trunks-Irl to ITI35. Similarly, the nine secondary subgroups serve as starting points for 135 outgoing trunks OTI to OTI35. The selector links are spread between the primary and secondary subgroups on the basis of each primary subgroup having access to at least one link extending to each secondary subgroup, and vice-versa. primary and two secondary subgroups are re- -quired,` half theA links from any primary subeach primary subgroup has access to three links extending to each of two of the secondary subgroups, and two links extending to each of the other seven secondary subgroups.

The following table shows the 'general spread arrangement vfor leach number of primary and secondary subgroups from two to twenty:

TABLE NO. 1

No. of links from any primary subgroup to No' of subgroups the secondary subgroups' When only two l to each.

7 each to two; 6 to one.

to each.

4 to .ach.

4 each to two; 3 each to four.

3 each to six; 2 to one.

3 each to four; 2 each to four.

3 each to two; 2 each to seven. 2 to each.

2 each tonine; 1 each to two.

2 each to eight; 1 each tofour.

2 each to seven; 1 each to six.

2 each to six; 1 each to eight.

2 each to ve; 1 eachto ten.

2 each to four; 1 each to twelve.

2 each to three; l each to fourteen. 2 each to two; l each to sixteen. 2 to one; 1 each to eighteen. f 1 to each.

In carrying out any of the general spread arrangements indicated in Table No. 1, an orderly specific arrangement may be adopted wherein the selector link extending from any primary sub-A group terminal extends to the correspondingly ment chosen and considered' preferable for the system of Fig. 2, wherein 180 selector links interconnect nine primary and secondary subgroups A to I. 1 .l f

TABLE NO. 2

From From To From 'l`o S01. Sel. Sel.

pn. sec. pri. sec. pri. sec. hnk term. term. 'lfmk term. term. lmk term. term.

l 1 B1 B1 41.--. C1 C1 V1 B2 B2 42.... o2 C2` 3 B3 B3V 43.--. C3 C3 4 B4 C4 44.... C4 D4 5 B5 C5 45.-.. C5 D5 6 B6 C6 46..-. C0 Dfi 7 B7 D7 47.-.. C7 E7 8 B8 .D8 48.... C8 EX v9 B9 E9 49.... C9 F9 1 B10 E10 50.... C10 F10 B11 F11 `51.... C11 G11 B12 F12` 52 C12 GIZ B13 G13 53.-.. C13 1113 B14 G14 54.-.. C14 H14 B15 H15 55.--. C15 115 B16 1116' 56.-.. C16 116' B17 117 57...- C17 A17 v13118 118 58.--. C18 A18 B19 A19 59.-.. C19 B19 B20 A20 60--.. C20 B20 From To From To From To Sel. Sel. Scl.

. pn. sec. pn. sec. pri. sec. lmk term. term. lmk term. term lmk term. term.

61.... D1 D1 81.--. E1 E1 101.- F1 F1 62.... D2 D2 82---. E2 E2 102.- F2 F2 63... D3 D8 83.-.. E3 'E3 103... 4 F3 F3 64.... D4 E4 84---. E4 F4 104-.. F4 G4 6. D5 E5 8. E5 F5 105.-- F5 (15 60.-.. D6 E6 86---. E6 F6 106..- IF6 G6' 67.... D7 F7 87--.. 7 G7 107... F7 H7 68.... D8 F8 88.... E8 G8 108... F8 118 69.... D9 G9 89.... E9 H9 109... F9 `I9 70.--. D10 G10 90.-.. E10 AH10 110.-- F10 110 71.-.. D11 H11 91.-.- 'E11 111 111.-. F11 A11 72.-.. D12 IIZ 92.--. E12 112 112.-. F12 Alf? 73-.-. D13 113 93---- E13 A13 113.-. F13 B13 74...` D14 114 94---. E14 A14 114... F14 B14 75.-.. D15 A15 95.--- E15 B15 115... F15 C15 76.--- D16 A16 9s E10I B16 116.-- El C162 77..-. D17 B17 E17 C17 117...- F17 D17 78..-. l D18 B18 E18 C18 118.-. F18 D18 79..-. D19 C19 E19 D19 119.-. F19 E19 80.-.. D20 C20 E20 D20 120--. F20 E20 From To From To From To Sel. Sel. Scl.

. pri. sec. pri. sec. pri. sec. kuk term term. hnk term. term. hnk term. term.

121... G1v G1 141--- Hl H1 I1 I1 122... G2 G2 142.-- H2 H2 12 12 123... G3 G3 143--. H3 113 13 I3 124... G4 H4 144. H4 I4 I4' A4 125... G5 H5 145.-- H5 I5 15 A5 126... G6 H6' 146... H6 16 I0 .lli 127--. G7 I7 147--- H7 A7 I7 v117' 1 128.-. G8 I8 148--- H8 A8 I8 B8 129--. G9 A9 149-1-- H9 B9 I9 C9 130..- G`10 A10 150.-- H10 B10 110 C10 131.-. G11 B11 151-.. H11 C11 111 D11 132... G12 B12 152... H12 C12 112 DIL'. 133--- G13 C13 153.-. H13 D13 113 E13 134.-. G14 C14 154.-- H14 'D14 114 E14 135 G15 D15 155..` H15 E15 115 F15 136.-. G16 D16 156--. H16 E16 116 Fili 137..- G17- E17- 157--. H17 E17 117 G17 138... G18 E18 158--. H18 F18 .118 G18 139... G19 F19 159.-- H19 G19 119 H19 140-.- G20 I.F20 160--- H20 G20 120, ...1120

NUMERIcAL GROUPING oF

OU'rcorNG TRUNKs

1, 2 and 0 are represented respectively by cables 2||,2I2,and22|'i.

For convenience in' grouping, the outgoing Atrunks OTI to OTI35 may be passed through an intermediate distributing frame indicated at IDF, across whichv each trunk may be carried by a separate jumper connection. The preferred astrunks, or fewer, while other numerical groups may contain twenty trunks or more, all depending upon the trailic requirements.

THE GROUP-CONTROL ARRANGEMENT In the arrangement shown in Fig. 2, ten group A controllers, GCI to GCU, correspond respectively to the ten numerical groups of outgoing trunks. Each group controller is arranged vto direct any primary switch in any subgroup to extend a connection to any outgoing trunk in the corresponding numerical group, by wayof a selector link and the concerned secondary switch. Any operating group controller is assisted in selection of an idle outgoing trunk by one or another of the nine secondary controllers SCA to SCI, according to the secondary subgroup through which connection with an idle trunk i'n the called numerical group is located. The secondarycontrollers are connected with the group controllers throughl the nine cables to '|I9. Since each secondary subgroup has its own secondary controller, each secondary subgroup is able to act as aunit independent of the others.

THE SELECTORS includesan arrangement of control relays (Fig.

3) for performing theI necessary' control functions, and for transmitting impulses to a register device, through which selection is made of one or another of ten so-called dialleads, one for each separate digit value employed to direct a call through the selector stage. ten digit values is employed for each of the ten -numerical groups 1 to 0 of outgoing trunks.

Each subgroup of selectors is provided with ten connecting relays, such as relays 40| to 4I0 of subgroup A, in which the dial leads DLI to DLO of that selector subgroup terminate. Through the selection and operation of one or another of the relays 40| to 4 I 0, connection is made with the A separate one of corresponding one of the group controllers GCI to GCU, by way of a local cable such as 450 and set of dial leads such as DLI to DLO, its own group of ten connecting relays such ets-40| to 4|0, and its own local cable such as 450, each selector subgroup, together with its associated primary subgroup of switches, is Yable to act as a unit independent of the` others.

THE CIRCUIT DnAwI-Nos IIhe circuit drawings of Figs. 3 to 8 will now be explained brieily. Fig. 3 shows in full the circuits of selector SEL-AI and indicates the Ilf- `teenth selector SEL-AIS by means of a rectangle.

intermediate selectors, form selector subgroup A These two selectors, together with thirteen tor. l

Fig. 4 shows three of the ten connecting relays 40| to 4|0 to which the dial leadsDLi to DLI) of selector subgroup A respectively extend. Each such relay, when. operated over its associated dial lead from any selector in selector subgroup A,

operates to interconnect conductors 3|0, 3| I, and the conductors in subgroup-A cable 450, to conductors in the associated one of the cables 42| to 430 extending respectively to the ten group controllers GC! to GCU.

Fig..5 shows the circuit arrangement of primary subgroup A of Fig. 2, primary switches PAI v and PAI 5 beingv shown.j The intermediate pri-- mary switches ofv this subgroup are omitted to conserve drawing\\space. Primary switch PAI,

for example, contains eleven selective stackups of the stackups of contacts 1 to 11. The select magnets for

stackups

1, 2, 10, and 11 are magnets 52|, 522, 530, and 53|. Select magnet 53|, associated with stackup 11 of.any primary switch of the subgroup, is operated or not (along with one of the magnets 52|y to 530) depending upon whether the lower contact set or the upper contact set of an operated stackup 1 to 10 is to be effective.

For the operation, and maintenance, of the` selected combination of stackups, each switch is provided with a hold magnet (50| for switch PAI,

and 5|5 for switch PAIS) The off-normal stackup ON of' any of the switches is not a selective stackup, being operated each time the corresponding hold magnet,

such as 50|, is energized, irrespective of what stackup selection has been accomplished.'

Each primary and each secondary subgroup or switches is provided with its own set of select magnets 52| to 53|, and with its own set of selecting shafts (not shown), whereby each subgroupfis capable of operating as a unit independent of the other subgroups.

Fig. 6 is a drawing corresponding generally to Fig. 5, but showingsecondary subgroup A instead of primary subgroup A. Here again, only the first and niteenth switches are shown, and stack- That is, l

Y similar.

4ups 3 to 9 are omitted. Magnets 62| to sal cor- Assuming the primary and secondary sub-- groups to b mounted in superposed relation as indicated in Fig. 2, spread cable 600 extends vertically between them and has lateral branches for the respective primary and secondary subgroups, Branches PA and SA are the lateral branches for primary subgroup A and secondary subgroup A. rIhis spread cable contains conductor sets comprising the selector links interconnecting the subgroups vof primary and secondary switches according to Table No. 2, appearing hereinbefore. Each selector link (such as SLI to SL20 extending from primary subgroup A) includes four conductors, a magnet conductor M, andthe usual tip, ring, and sleeve conductors i T, R, and S. The magnet conductor M in any selector link is the conductor over which the one of the ten select magnets lsuch as 62| to 630 is operated in the secondary subgroup to which such link extends, Awith or without operation of the associated eleventh select Amagnet such as 63|.

The six contact pairs instackups 1 to 10 of any switch comprise an upper set of three and a lower set of three, each switch having ten upper sets and ten lower sets. lThe upper sets represent terminals l to 10, respectively, of the subgroup, while the lower sets represent terminals 11 to 20, respectively. Stackup 11 of any switch .is operable to render sets 11 .to 20 effective in place of sets 1 to 10.l

Fig. 7 shows the circuit arrangement at group controller GCI of Fig. 2, the circuit arrangement at each of the other group controllers being Group controller GCI includes 'start and test relays 'IOI and "|02, a' pair of busy relays 103 and y 104, a pair of preference-shift relays |05 and 106, and twenty-seven link-test relays IA to 31. The

llink-test relays are assigned inl subgroups of three to test the links extending from a calling primary subgroup to the respective secondary subgroups. 'I'his is in accordance'with Table No. 2, 'wherein it will be noted that not more than threel selector links extend from any primary subgroup to any secondary subgroup. Relays IA to 3A are assigned to links extending from-a calling primary subgroup to secondary subgroup A; relays IB to 3B ,are assigned to links extending to. secondary subgroup B; and so on, to relays II to 3I, which are assigned to links extending from a ycalling primary subgroup to secondary subgroup I. l

Group controller GCI is connected with selec- I tor subgroups A to 'I by the conductors in cable 42| incoming to Fig. '7 from Fig. 4. Group controller GCI is also interconnected with the nine secondary controllers (SCA to SCI), by conductor sets IA, IB, and so forth, to II, lying respectively in cables |II to 'II9. These cables carry similar conductor sets to the secondary controllers from the other group controllers. AThese other conductor sets (not shown in Fig. 7) may be similarly labeled 2A to 2I, 3A to 3I, and so forth, to 0A to 0I, according lto the groupI controller at which they originate.

line ITI incoming to the selector stage.

Fig. 8, comprising' parts I and`2, shows secondary controller SCA of Fig. 2. the otherl secondarycontrollers being similar. Relays TI to TI5 are test relays corresponding respectively to the iifteen trunks, OTI to OTI5, outgoing 4from the associated secondary subgroup A. The in-I terconnection between the outgoing trunks and relaysfTI to TI5 is through conductors SI to SI5 in cable 650, and by way of contacts of connecting relay 02 I when operated.

Relays to 8I0 are numerical-group relays assigned respectively to numerical groups 1 to 0 of outgoing trunks.v Each such numerical-group relay is controllable only from the corresponding group controller, and then only if the secondary controller is idle. Upon the operation of any numerical-group relay, Voperations occur to mark the secondary controller busy to the remaining group controllers, fas will-'i appear subsequently, and to initiate the operation o'f the switching apparatus to complete the connection.

DETAILED DESCRIPTION Referring now particularly to Fig. 1, the general operations involved in setting up a connection from a calling substation A to `a called substation B will now be described. y

When the -receiver (notshown) is removed at substation A, a direct-current bridge is estab-v lished across the tip and ring conductors of the associated line, operating line relay IOI through contacts of cutoff relay, I02'to cause nder action to occur at the associated nder stage.` As a result of this finder action, the tip, ring, and sleeve conductors of the calling line are extended in any desired manner to an idle trunk line such as trunk ITI, it may be pointed out, is shown also in Fig, 5, incoming to the primary switch PAI. line ITI 'is normally marked idle by an idle-indicating battery potential applied to the sleeve conductor S thereof by way of contacts of release relay 302 and contacts in stackup ON of the associated primary switch PAI, the connection being made by way of the illustrated current-limiting resistor,...

When the finder-stage extension has been made,

.line relay 30| associated with trunk ITI (being a relay -of selector SEL- AL Fig. 3) operates over the calling line, causing operation of the associated release relay 302. Relay 302 disconnects the normally applied idle-indicating battery potential and substitutes ground potential to maintain in the usual manner the connection establishedI through the finder stage, closing arr'operating circuit 'for cutoff relay |02. Relay |02 thereupon operates to disconnect the line-relay bridge, whereupon line relay IOI restores.

The calling subscriber may now dial the rst digit in the number assigned to the line of substationi B, causing the usual series of interruptions to be produced in the bridge across the calling line by the usual form of calling device. The resulting series of momentary restorations of line relay 30| causes a Vselecting operation to occur in a manner to be explained subsequently in connection with Fig; 3. Upon the termination of the dialing of this digit, operations occur to test the selector links such as SLI accessible to pri- The trunk