Patent GB-431995-A (GB)
Title: Improvements in or relating to electric submarine signalling cable systems
IPC: H04B3/44
Filed: 1934-12-11
Abstract: 431,995. Repeating systems. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Jacobs, O. B. ; 20, Hamilton Road, Morristown, New Jersey, U.S.A.) Dec. 11, 1934, No. 35550. Convention date, Dec. 15, 1933. [Class 40 (iv)] In arrangements for feeding from a terminal station over the signal conductor direct current for operating the amplifiers of an intermediate repeater in a submarine cable, several supply units are provided and switching means is such that any unit can be switched in or out without interrupting the continuity of the circuit through the signal conductor and the remaining units. In the system shown, two sets of similar units 28 ..2811 and 38 .. 38<11> are connected either separately or in parallel over switch 20 between conductor 21 and an earthed lead 22. Each unit comprises a battery 27 and a four-armed switch 30.. 33, which in the position shown connects battery 27 to charging mains 29, the conductor 21 being fed from one of the other sources 28<1>, &c., over switch arm 31. Movement of the switch to the right first cuts off the charging leads 29 and then connects battery 27 and resistance 34 in series between unit 28<1> and conductor 21 but with a short-circuit at arms 30, 31. In further movement this short-circuit is removed and on still further movement resistance 34 is short-circuited so that battery 27 is then connected over switch arms 31, 32, 30 directly between unit 28<1> and conductor 21. On unit 38, an additional stage in the switching operations is provided by a resistance 45 connected up prior to the direct short-circuit across battery 27 and resistance 34. An excesscurrent alarm-relay 35, an automatic currentregulating circuit comprising valves 46 and a biassing resistance 47, and a one-way shunt 49 to pass current from the battery at the other end of the system when the local battery is open-circuited, may also be provided. For completely disconnecting the supply voltage from the cable the interlocking arrangements of Fig. 2 are employed. In the position shown, conductor 21 is connected through slider 52 and magnet 50 to cable conductor 10, and conductor 22 through switch 53 to direct-current earth 61, a separate signal earth 62 being provided. During the downward movement of slider 52 an increasing resistance is inserted between conductor 21 and the cable, and a decreasing resistance in shunt to earth until at the lowest position the supply is completely disconnected and locking magnet 50 falls back, permitting switch 51 to be operated to connect the cable to earth over jack 56 for testing purposes. Two cables 10, 110 may be fed in series, with the elimination of the direct-current earths 61, 161, by operating switches 53, 153, shuntresistances 60, 160 affording means for relative adjustment of the currents in the two cables. If an earth fault develops at any point on the cable its effect may be minimized by arranging for the normal potential of that point to be close to zero by suitable adjustment of the supply voltages at the two ends of the cable, and, when two cables are supplied in series, by adjustment of resistances 60, 160. Modifications are described in which the direct-current earth is provided at an intermediate repeater or at two adjacent repeaters, the latter arrangement rendering the supply circuits from the two ends of the system independent of one another. Specification 425,639 is referred to.