BE346579A - - Google Patents

Description

       

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 EMI1.1
 



  "IMPROVEMENTS Mw. LINKAGE DEVICES BETWEEN SIGNALING CURRENT GENERATORS AND ELECTRICAL DISTRIBUTION NETWORKS".



   The present invention relates to a device making it possible to superimpose signaling currents, generally of high frequency, on the currents supplied by electricity distributions. according to the present invention, this device is entirely independent of the type of electricity distribution system used, and it simply provides a coupling means between the signaling current generator and the sheave into which it is desired to inject this current.

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   According to one characteristic of the invention, the signaling current generator, which can be of any polyphase type, for example three-phase, supplies the secondary windings of a system of air-gap transformers or of a single polyphase transformer. with an air gap, the primary windings of one or of which are respectively mounted on the conductors of a feeder supplied by the bus bars of the electrical distribution system.



   According to a second characteristic of the invention, fixed or variable capacitors are mounted between the signaling current generator and the secondaries of the air-gap transformer (s), in order to limit the value of the power-frequency current supplied by these secondaries. through the windings of the signaling current generator.



   According to a final characteristic of the invention, the primaries of the air-gap transformer (s) are arranged with a view to playing the role of reactance coils in the event of a short-circuit on the line.



   In the accompanying drawing, the invention is shown as being applied to a three-phase system.!.,! and 3 respectively represent the bus bars of a three-phase current distribution station 4. 5,6 respectively represent the three conductors of one of the feeders of the distribution; 7,8,9 are respectively the three windings primary of the three air-gap transformers of which 10, 11 and 12 are respectively the three secondary windings. It goes without saying that the said windings can be mounted on three separate magnetic circuits or on the three cores of a three-phase transformer.

   Windings 7,8,9 are respectively- @

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 ment mounted on conductors 4,5 and 6; 13, 14 and 15 are the three capacitors respectively in series with the secondary windings 10, 11 and 12 on the one hand and with the windings 16, 17 and 18 of the three-phase signaling current generator on the other hand.



   The transformers will be calculated so that the induction corresponding to the full load current remains well below saturation; this in order to reserve a sufficient margin for the flow having the frequency of the signaling current.



   Furthermore, one should not choose a value that is too low for this induction; this is to avoid excessive overvoltages in the event of a short circuit on the feeder.



   The induction adopted for the flux at the signaling frequency must be lower than the maximum induction generated by the distribution current; this is to limit the magnetizing current and the losses in the iron at the signal frequency.



   In addition, the capacitors 13, 14 and 15, the main purpose of which is to limit the value of the power-frequency current delivered (by the secondaries of the transformers through the windings of the signaling current generator could be fixed or even variable and in in the latter case they will be adjusted for the frequency of the signaling current.



   When no signaling current is emitted, the secondaries of the transformers used for the transmission can possibly be short-circuited * But this operation can be made unnecessary if care is taken to avoid excessive heating. iron and limit the reactive voltage drop across the primary windings to an acceptable value.



   It should be noted that by carrying out the latter

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Claims (1)

Under these conditions and in the event of a short-circuit on the network, the primary circuits of the transformers can play the useful role of reactance coils. ABSTRACT EMI4.1 - "-" 'I .. ---.... Coupling system between a generator of generally high frequency signaling currents and an electrical distribution network into which it is desired to inject this current, a system characterized in that the signaling current generator, which can be of a poly- type Any phase, for example three-phase, supplies the secondary windings of a system of air-gap transformers or of a single polyphase air-gap transformer, the primary windings of the one or of which are respectively mounted on the conductors of a feeder powered by the bus bars of the electrical distribution system. This coupling system may further be characterized by the following points, together or separately. a) Fixed or variable capacitors are mounted between the signaling generator and the secondaries of the air-gap transformer (s), in order to limit the value of the power-frequency current delivered by these secondaries through the windings of the generator. signaling current. b) The primaries of the air-gap transformer (s) are arranged so as to play the role of reactance coils in the event of a conrt-cirit on the line. EMI4.2 aF.-.- .. ". il ... / #, -? ... y / y / 7