SYSTEM DESIGN — NEWFOUNDLAND-NOVA SCOTIA LINK 227 



power units energizing the land and sea cables respectively; this ar- 

 rangement has been particularly useful during the installation period. 



The presence of high voltages on the cable constitutes a potential 

 danger to personnel, hence special precautions are taken in the design 

 of the equipment in which the cable terminates and in which high volt- 

 ages exist or may exist. 



The ground connections for the power circuits at the two ends are via 

 special ground cables and ground plates located about half a mile from 

 the main cable, and metering arrangements are provided to check that 

 the current does in fact take this path. These measures ensure that the 

 current returning via the cable armour is never sufficient to cause serious 

 corrosion. 



Arrangement of Terminal Equipment 



Fig. 7 show the arrangement of the terminal equipment. In accord- 

 ance with an early agreement defining precisely the various sections 

 of the project, the link is considered to terminate at the group distribu- 

 tion frames at Clarenville and Sydney Mines, i.e. at the 60-108 kc inter- 

 connection points. 



In addition to the cable-terminating and power-feeding equipments 

 (A and B) , the following are provided at the terminals : 



(a) Submarine-cable terminal equipment (C) consisting of repeaters 

 to amplify the signals transmitted to and received from the cable, 

 equalizers and frequency-translating equipment to convert the line fre- 

 quencies to basic supergroup frequencies (312-552 kc). 



(6) Group-translating (group-bank) equipment (D) to convert the 

 basic supergroup to five separate basic groups (60-108 kc) and vice 

 versa. 



(c) Equipment for the location of cable and repeater faults (E and F) . 



(d) Speaker and printer circuit equipments (G and H) to provide 

 two reduced-bandwidth telephone circuits, two telegraph circuits and 

 one alarm circuit for maintenance purposes. It is clear that such circuits 

 should be substantially independent of the main transmission equip- 

 ment. 



Two principles were agreed very early in the planning; first, that the 

 engineering of the various links should be integrated as far as possible, 

 and second, that the items of equipment at each station should be pro- 

 vided by the party best in the position to do so. In consequence: 



(i) Items of standard equipment were provided by the A.T. and T. 

 Co. at Clarenville and Sydney Mines (and by the Post Office at Oban), 

 thus simplifying maintenance and repair problems. 



