Patent GB-1121059-A (GB)
Title: Electrical switching arrangements for use in an automatic telecommunication equipment
IPC: H04Q3/00
Filed: 1966-12-09
Abstract: 1,121,059. Automatic exchange systems. INTERNATIONAL STANDARD ELECTRIC CORP. 9 Dec., 1966 [16 Dec., 1965], No. 55217/66. Heading H4K. In a reed relay switching network which is divided into two multi-stage sections that are interconnected by links, the trunking in each section is of the star type, i.e. it is such that only one possible path exists between any one inlet and any one outlet of a section although a plurality of paths exist between any one inlet and any outlet of the network as a whole. In order to select a route, the calling inlet and all idle outlets of the network are marked, whereby marking potential fans out towards the links via the relay operate/hold wires of all available paths in both sections. One of those links which are marked by both sections is selected (by means not described) and thereafter new markings are applied between this link and the outlets so that one of the latter can be selected for use. The marking potential is replaced by operating potential in order to bring up the cross-point relays in the chosen path and thereafter holding potential is applied to the path from the link. The cross-point matrices, which utilize two-winding reed relays having oppositely poled diodes in series with each winding, and the method of operating and holding these relays are more fully described in Specification 1,109,209. Trunking.-A fully equipped network (Fig. 1, not shown) comprises 1024 inlets arranged in 64 groups of 16 lines each and 16 outlets, e.g. registers with 128 links between the two sections. The inlet section consists of four stages, of, respectively, two hundred and fifty-six 4 x 4 matrices; two hundred and fifty-six 4 x 2 matrices; sixty-four 8 x 4 matrices; and thirty-two 8 x matrices, the A, B stage matrices being divided into 64 groups and the C, D stage matrices being divided into 8 groups. The outlet section comprises three stages, of, respectively, sixteen 8 x matrices; sixteen 4 x 2 matrices; and eight 4 x matrices, the E and F stage matrices being divided into 4 groups. For simplicity, the network actually described (Figs. 2 and 3, not shown) comprises only 8 inlets, 8 links and 4 outlets, the matrices being of 2 x 2 type and there being only 3 stages in each section. Particular description. Fig. 5.-The crosspoint relays KP and KPr of inlet section AB1 and outlet section AB2 comprise operate and hold windings but only one of the latter, viz. Kp11 II is shown, the connection of the remainder being obvious from this. At rest, all free outlets E1-E4 have earth potential applied to their points P5 via their respective diode switches D1, D6, D7 and common contact c, whereby at least some of the points P2 on the link (or inlet) side of the outlet section also attain earth. In response to a calling condition, denoted by closure of contact k1, an earth potential appears at some of the points P1 on the link (or outlet) side of the inlet section. Consequently some of the link coincidence gates KS1, KS4 &c. are opened and selection circuit AWE 1 chooses one of them by operating one of the B relays. The relevant reed relays of AB1 come up in series with the hold winding II of relay, e.g. B1 and relay C. Relay F follows, whereby the earth marking is removed from the network outlets and is replaced by a negative battery marking. Another selection circuit AWE2 chooses one of the free outlets, whereby relay, e.g. E1 the relevant cross-point relays and relay H operate in series over the contact b2 of the actuated B relay. A relay G follows slowly and brings up the M1 relay of the link, whereby positive holding battery is supplied to the reed relays in the two sections of the network. The gate D1, D6, D7 of the just completed path is closed so as to busy this outlet of the network. Relays G, H, C and F restore. In order to release the connection a contact (not shown) in series with M1 is opened.