FR2460570A1 - AMPLIFICATION CONNECTION FOR A DEVICE FOR THE ACTIVE PROTECTION OF TELECOMMUNICATION LINES AGAINST PARASITES GENERATED BY STRONG CURRENT FIELDS - Google Patents

Abstract

A. AMPLIFICATION CONNECTION FOR A DEVICE INTENDED FOR THE ACTIVE PROTECTION OF TELECOMMUNICATION LINES AGAINST PARASITES GENERATED BY STRONG CURRENT FIELDS, CONNECTION INCLUDING AN AMPLIFIER THE OUTPUT OF WHICH IS RETROCOUPLETED TO THE INPUT, AND IS ALSO CONNECTED TO THE INPUT PRIMARY WINDING OF A COUPLING TRANSFORMER. B. CONNECTION CHARACTERIZED IN THAT THE PHASE SHIFT CAUSED BY THE LINE RESISTORS AND POSSIBLY THE PHASE SHIFT INTERVENING IN THE COUPLING TRANSFORMER 6 AS A RESULT OF THE LOSSES WHICH EXPERIENCE THERE ARE INTRODUCED IN THE RETRO-COUPLING. C. THE INVENTION APPLIES IN PARTICULAR TO TELECOMMUNICATION LINES.

Description

The present invention relates to a connection of am-

  for a device for the active protection of telecommunication lines against pests caused by

  strong branch current fields with amplification

  the output of which is back coupled to the input, and is also connected to the primary winding of a coupling transformer.

  The feedback already known from the output of the am-

  amplifier on the input of the amplifier, serves to stabilize this amplifier and to obtain a good reduction factor. In

  In addition, this backlinking is accompanied by a mid-distortion rate of

  nimal. It stabilizes the amplifier and, by varying the degree of coupling, the zero amplitude of the reduction device can

to be adjusted.

  FIG. 1 is a partial schematic representation of an amplification branch according to the state of the

  technique which has just been described.

  From the pilot wire 1, the parasitic voltage to be compensated is sampled and in 2 it is applied to the input

  of an amplification system which consists of a pre-amplification

  3 and a power amplifier 4. The output of the power amplifier 4 is connected to the winding

  of a coupling transformer 6, whose coils

  Secondary elements 7 are located on the route of the telecommunications conductors 8 to be protected. The pilot wire 1 passes through another secondary winding 9. The output of the amplifier 4 is connected via a

  group of resistors 10 determining the feedback factor

  coupling, to another input 11 of the pre-amplifier 3. From the pilot wire 1, the existing residual voltage is taken behind the control winding 9 and is applied to an auxiliary amplifier 12 and a Schmitt trigger 13 for allow monitoring of this residual voltage

  which eventually triggers an alarm 14.

  It has been found that, by variation of the back-coupling, the reduction factor obtained can be easily reduced to a minimum, but that the remaining remainder can no longer be compensated for in amplitude because, due to phase shifts as well as as a result of the line resistances, and also as a result of the losses in the coupling transformer, a residual voltage 2 - continues to subsist and can not be compensated with

the classic connections.

  The object of the invention is to create a connection which also makes it possible to reduce the residual residual voltage.

  For this purpose, the invention relates to a connection

  characterized in that the phase shift caused by the line resistors and possibly the phase shift occurring in the coupling transformer, as a result of

  losses which are manifest in it, are introduced into the

  beach. The invention will be described in more detail with reference to the accompanying drawings, in which:

  FIG. 1 represents a branch of amplification

  cation corresponding to the state of the art,

  - Figures 2 to 9 respectively represent different

  variants of the amplification connection according to the invention. Only for the introduction of the phase shift caused by the resistances of lines, it is sufficient, according to

  the invention, to take back-coupling at the input of the coil.

  primary element of the coupling transformer, as shown in Figure 2, at 15. This is particularly true when the line 16 is relatively long between the output of

  the amplifier 4 and the transformer 6 and thus the inductor

  primary winding 5 is connected upstream of the

  resistance characteristic of line 16.

  In addition, to detect the phase shift indi-

  In the coupling transformer 6, several paths can be used in accordance with the invention. Firstly, the back-coupling, as shown in FIG. 3, can pass through a portion of the primary winding of the coupling transformer via the sockets 21. The position of the socket must be chosen. in each particular case, depending on the extent to which the ohmic resistance of the primary winding is to be detected and the extent to which the current flowing in the primary winding

must influence the retro-coupling.

  To dissociate relationships, going in the opposite direction

  between the ohmic resistance and the retrocoupling, according to a 3.-

  another form of the invention shown in FIG.

  coupling goes through a secondary winding

  17 of the coupling transformer 6. According to this arrangement,

  the feedback voltage is independent of the primary current flowing. According to another embodiment of the invention,

  particularly suitable for retrofitting equipment

  already existing protective devices, because in these connections the primary winding of the coupling transformer has no taps and there is no secondary winding available in accordance with this embodiment of the invention, the backcoupling constituted by from the differential signal between the

  signal on the pilot wire and the signal at the output of the ampli-

  the driver, as shown in FIG. 5, is led via the auxiliary amplifier 12 to the driver

  18 and achieves, through the resis-

  division 199 at the counter-coupling input 11 of the

  3. In contrast to embodiments previously

  described in which the entire signal present at the output

  In the present embodiment of the invention, the difference between the amplifier and the amplifier is used for the residual compensation to the difference between the pilot wire signal and the output of the amplifier. As this difference is, on the one hand, very small, and since, moreover, it is shifted into phases of 1800, an inversion of

  phases and adequate amplification should be

  kill in the additional booster amplifier 12.

  From a certain degree of amplification, such amplifiers according to the preceding paragraph, tend to

  to oscillate. To avoid this, according to another form of the invention,

  and as shown in Figure 6, a component

  the additional back-coupling is provided in a

  known, between the output of the amplifier and the input of that-

  here, so that the main stabilization of the ampli-

  3 and 4 is effected by means of this additional back-coupling 20, while the residual component resulting from the phase shift passes via the amplifier

12 and resistance 19.

  As a variant with respect to this solution, this additional component of the retrocoupling can, like this

4 -2460570

4.-

  is shown in Figure 7, be taken at the entrance of the

  primary bearing to incorporate power supply conductors

  16 extremely long. Another variant is represented

  in Figure 8 o the additional component of the counter

  coupling passes through a portion of the primary winding of the coupling transformer via the jack 21,

  part of the ohmic resistance proportion of the trans-

  trainer is already taken into account in the main compensation. Finally, according to Figure 9, the component

  additional retro-coupling may be obtained through

  the secondary secondary winding 17 of the coupling transformer, which makes it possible to obtain degrees of compensation.

even higher.

5.-

Claims (6)

R E V E N D I C A T I 0 N S   1.- Amplification connection for a device for the active protection of telecommunication lines against noise caused by current fields for%, connection comprising an amplifier whose output is adjusted   trocoupled on the input, and is also connected to the coil.   primary element of a coupling transformer, characterized in that the phase shift caused by the line resistors and possibly the phase shift occurring in the coupling transformer (6) subsequently   - losses which manifest themselves there, are introduced into the retro- coupling.   2.- Connection according to claim 1 for the in-   troduction of the phase shift caused by the line resistors, connection characterized in that the back-coupling is taken at the input (15) of the primary winding (5) of the coupling transformer (6).   3. Connection according to claim 1, characterized   rised in that the retro-coupling goes through a   part of the primary winding (5) of the beach (6).   4. Connection according to claim 1, characterized   in that the back-coupling passes via a separate secondary winding (17) of the coupling transformer (16).   5.- Connection according to claim 1, in the-   wherein the pilot wire is connected to a secondary winding of the coupling transformer, characterized in that the feedback consists of the differential signal between the signal on the pilot wire (1) and the signal at the output of the amplifier,   passes through an auxiliary amplifier (12).   6. Connection according to claim 5, characterized   in that an additional component of the back-coupling goes in a manner known per se, from the output of the amplifier at his entrance.   7.- Connection according to any one of the   2 and 6, characterized in that the additional component   retro-coupling is taken at the inlet (15) of the coil. primary (5).   8.- Connection according to any one of the   6.- dications 3 and 6 or 4 and 6, characterized in that the   additional component of retro-coupling goes through   part of the primary winding (5) of the trans-   coupling trainer (6) or through the intermediary of the   separate secondary bearing (17) of the coupling transformer (6).