GB434559A - Improvements in or relating to the regulation of currents having high or musical frequencies superimposed on distribution networks - Google Patents

Abstract

434,559. Signalling over power circuits. COMPAGNIE POUR LA FABRICATION DES COMPTEURS ETMATERIEL D'USINES A GAZ, 12, Place des Etats-Unis, Montrouge, Seine, France. July 10, 1934, No. 20265. Convention date, July 11, 1933. [Class 40 (i)] In a system for signalling over power distribution networks by high or musical frequencies superposed thereon, an estimate of the voltage (across B, C) available at the receivers connected to the feeders 3 .. 6 is made by measuring the difference between the voltage put in to the superposing transformers (7 .. 10) and the voltage at a point (transformer 21) in the network on the near side of the superposing transformers. This differential voltage is then used automatically to adjust the input voltage to a desired value, or the adjustment may be made manually. The invention may be applied to continuous or multi-phase current networks, but as shown is applied to a single phase network comprising mains 1, 2 and feeders 3 to 6. The signalling source 17 is connected automatically or manually by a switch 16 to the superposing transformers 7 .. 10. The differential voltage due to transformers 21, 22 is fed over a circuit 26 ..28, rejecting the power frequency but resonant to the signalling frequency, to a rectifier which supplies a galvanometer 31. The galvanometer needle 32 is adapted to close contacts 34, 35, according to whether the voltage is excessive or insufficient, to drive a motor 37 in one or other direction for the purpose of adjusting the output of generator 17. Several signalling frequencies may be used, the circuit 26-28 being tuned according to the frequency in actual use. The signals may be modulated or intermittent, in which case the measurement and adjustment is effected by a preliminary unmodulated transmission to which the receivers do not respond.