The full-automatic exchange at Frederiksdal

The Frederiksdal exchange is of the rotary 7 D type. The exchange has an initial equipment for 1 000 subscribers' lines but the present building permits an extension up to 2 000 lines. The number of call minutes per subscriber in the busy hour is 2, corresponding to 200 call minutes per busy hour per group of 100 subscribers, of which 78% is reckoned to be outgoing traffic and the remaining 22% local traffic. The average conversation time is 3.5 minutes. From these data 4 first line finders, 5 combined line finders and final selectors and 4 regular final selectors per 100 subscribers has been fixed. For the whole exchange 54 links, 12 registers, 48 penultimate group selectors and 42 incoming and outgoing junctions to Lyngby are provided. A 48 V low-resistance supervisory bridge was decided on, necessitating a new type of subscriber set with low-resistance transmitter. The maximum allowable loop resistance on junctions and subscriber lines is 1 200 Omega and minimum leakage 10 000 Omega. The paper describes the operation of the system.