Trends in Telephone and Power Practise as Affecting Coordination 

 By W. H. HARRISON and A. E. SILVER 



The general trends in telephone and electric power systems are ontlineil 

 and the reactions of certain of these trends on coordination are described. 



In the telephone system, brief mention is made of the rapid growth of 

 the dial system of operation, improvements in subscriber-station apparatus, 

 rapid extension of new types of facilities for toll circuits and the growth of 

 connections to foreign countries. Improvements in telephone service 

 increase the importance of securing adequate coordination. The advantages 

 of the use of cable facilities for toil circuits, of repeaters, of carrier current 

 systems as regards coordination of long distance and interurban telephone 

 circuits are discussed. The benefits accruing from improved subscriber- 

 station apparatus, central office equipment, abandonment of iron wire for 

 the short tributary toll circuits and new methods of making sleeves at joints 

 in open wire lines are outlined. 



In the power system, brief mention is made of increasing use of larger 

 generating units, and growing use of automatic devices to replace manual 

 operation. Improvements in power service generally react favorably on 

 coordination. The general trends toward higher voltages for transmission 

 and distribution and the improved standards of construction accompanying 

 these trends are described. The important matter of system stability and 

 the practises as regards grounding of transmission circuit neutrals, lightning 

 control and current limiting devices, and the reactions of these matters on co- 

 ordination are outlined. Reference is also made to grounding of distrilaution 

 svstem neutrals, service taps on transmission lines, general practises as 

 regards transformer connections and improvements in wave shape in so far 

 as these matters react on coordination. 



In conclusion, it is pointed out that, while there have been mfluences 

 working both favorably and unfavorably toward coordination, the pre- 

 ponderant trend is defin'itelv toward an improvement. The benefits which 

 have accrued from the activities of the Joint General Committee and the 

 important function of the Joint Subcommittee on Development and Re- 

 search are also mentioned. 



T 



General Trends 



■HE important benefits resulting from the cooperative handUng of 

 questions arising from the proximity of the physical plants of the 

 telephone system and the electric power systems of the United States 

 are emphasized when consideration is given to the e.xtent and the rapid 

 growth of these two industries. This growth is illustrated by Fig. 1 

 which shows that during the past decade, while the population of the 

 country has increased 16 per cent annual telephone messages have in- 

 creased 96 per cent and annual kilowatt hour usage of power 107 per 

 cent. Another indication of the grow^th of these utilities is given by 

 Fig. 2 which shows that during the past decade customers telephone 



* Part I of the Symposium on Coordination of Power and Telephone Plant. 

 Presented at the Winter Convention of the A. I. E. E., New York. X. V., January 

 26-30, 1931. Published in abridged form in Electrical Engineering, March, 1931. 



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