Patent GB-190306829-A (GB)
Title: Improvements relating to Relay Working of Submarine Cables or the like.
Inventor: BROWN SIDNEY GEORGE
Filed: 1903-03-24
Granted: 1904-03-24
Abstract: 6829. Brown, S. G. March 24. Telegraphs.-Relates to improvements in the relay working of submarine cables &c. bv the method described in Specification No. 18,261, A.D. 1898, and in means for transmitting Morse signals through the cable. In the " magnifying relay " described in the aforesaid Specification, the suspended coil which receives the line currents serves to actuate a second coil suspended in an alternating magnetic field so as to embrace more or less of the alternating lines of force and induce an alternating current, which is rectified before reaching the receiving-instrument. The alternating current may be generated by a multipolar direct-current motor having slip rings joined to points on the armature winding. Instead of supplying an alternating current to the field magnets a, Fig. 1, of the magnifying-relay, an electromagnetic interrupter c may be used, the break being shunted by a condenser e. The interrupter may carry further contacts d, d in the circuit of the suspended coil a' adapted to rectify the alternating currents induced in it. Instead of rectifying the alternating current produced in the suspended coil, it may be employed as shown in Fig. 2 to vibrate the suspended coils of two permauent-magnet relays f so as to interrupt the normal flow of current through their back stops g'. In addition to the windings on the relays f which receive the induced alternating current from the suspended coil a<1>, there are windings which receive a steady alternating current induced in the coil h on the field magnet a and controlled by a variable resistance h'. The steady alternating current is almost sufficient to cause vibration of the suspended coils of the relays f, and the other windings are opposite in direction on the two coils, so that for a given mcvement of the suspended coil a' one of the coils f<1> will be set in vibration, while in the other the tendency to vibrate will be diminished, a distinction being thus preserved between positive and negative line currents. Instead of utilizing the vibration produced in a suspended coil, a tuning-fork provided with a suitable contact-device may be caused to vibrate by means of an electromagnet through which the induced alternating current passes. In the apparatus shown diagrammatically in Fig. 4, the alternating- current electromagnets k act differentially on the soft-iron armature l, the balance being disturbed when an induced alternating current from the auspended coil flows round the windings k<1>. The armature actuates a relay tongue l<1> or the siphon of a siphon recorder. The " magnifying relay " may be used to work instruments shunted by the "magnetic shunts" or inductance coils described in Specification No. 1434, A.D. 1899. The magnetic shunt may be formed with an air gap, adjustable or otherwise. If " dot " and "dash " signals are sent over the cable the successive signalling impulses are preferably of opposite polarity so as to avoid running the dots together. The relay is then arranged so that a deflection in either direction closes the circuit of the sounder or other receiving-instrument. A commutator is used to reverse the battery after each signal, or, as shown in Fig. 6, the transmitter may work a sounder or relay the armature of which bears a pawl p, which actuates the ratchet-wheel q so as to connect the two sides of the split battery o to line alternately. In some cases the magnifying-relay may be omitted, the alternating current required to work the local relays being produced by means of the current from the line passed through a commutator or current interrupter.