| 摘要 |
<p>568,788. Converting electric currents. LANDIS & GYR SOC. ANON. Sept. 28, 1942, No. 13570. Convention date, Oct. 29. 1941. [Class 38 (ii)] [Also in Group XXXVIII] In a system for signalling over a power net,- work by means of impulses of alternating current, the signalling frequency is obtained by static frequency conversion by the use of a grid-controlled discharge tube. The converter may be fed from an A.C. or a D.C. network and the signalling current may be applied to the same or to another network. As shown, the primary windings of a single-phase transformer 12 are fed from a polyphase network 8 through a transformer 9 and are connected to the anodes of a mercury-vapour discharge tube 11, of which the grids are made operative in succession by an electrical or mechanical distributer 18. Condensers 14 across the primary windings and an inductance 13 between the cathode and the neutral point of the transformer 9 serve for smoothing purposes. The signalling current is applied through a transformer 21. to a network 10, which might be two phase wires of the network 8, over impulse contacts 25 which are controlled by a transmitter 1 to effect corresponding movement of a selecting switch 3 at the receiving point.</p> |
