JPH03154523A - Branching device for dc superimposition signal transmission system - Google Patents

Abstract

PURPOSE:To reduce the number of components by incorporating the function of a coil for DC bypass to a transformer. CONSTITUTION:A capacitor 4 is connected in series between the end (point c) of a 1st winding and a start (point d) of a 2nd winding. A DC power supply not shown in transmitted between a trunk line cable 1 and a branch line cable 2 via windings 31, 34 of a transformer 3. Only the AC component of a signal from the cable 1 is sent to the branch line cable 1 through the entire windings 31-34 of the transformer 3 and the capacitor 4 while being boosted to a multiple of 3<1/2>. Conversely, a signal from the branch cable 2 is sent to the trunk line cable 1 while being deboosted to a multiple of 3<-1/2>. Since the function of the coil for DC bypass is incorporated in the transformer 3, the number of components is reduced.

Description

[Detailed description of the invention] [Industrial application field]

This invention is a transmission system that supplies DC power to distant terminal stations (also simply referred to as terminals) and superimposes an AC signal on this DC to exchange information between terminals (in the present invention, this transmission system is used for convenience). The present invention relates to a branching device used in a DC superimposed signal transmission system (that is, a device that branches a transmission line while converting impedance in order to transmit signals efficiently and while suppressing reflections). Note that in the following figures, the same reference numerals indicate the same or corresponding parts.

[Conventional technology]

FIG. 2 shows an example of the configuration of this type of DC superimposed signal transmission system. In the figure, l is the main cable, 2 is a branch cable branched from the main cable, 02 is a terminator installed at the end of the main cable l to prevent signal reflection, and 03 is a DC power supply directly connected to the main cable. , 04 is the trunk cable l
The main station provided above, 05 the terminal provided on the branch cable, and 5 or 5A the aforementioned branch. In this transmission system, the DC power supply 03 is connected to the trunk cable 11 and the branch 5
or 5A, and each terminal 05 via branch cable 2
is supplied to In addition, the main station 04 is also connected to the main cable network.
Communication is performed with each terminal 05 via the branch 5 or 5A and the branch cable 2. FIG. 3 shows an example of the configuration of a conventional turnout 5. As shown in FIG. In the figure, DC power transmission between the main cable l and branch cable 2 is performed via a coil 25, and AC signal transmission is performed via a transformer 23 after blocking the DC component with a capacitor 24. be exposed. However, it is assumed here that the impedance of the coil 25 is sufficiently large in the frequency band of the AC signal and can block the AC signal.

[Problem B that the invention attempts to solve]

However, the conventional turnout 5 has a problem in that it has a large number of parts. Therefore, it is an object of the present invention to provide a branching device for a DC superimposed signal transmission system that can solve this problem.

[Means to solve the problem]

In order to solve the above problems, the turnout of the present invention has lr2
A branching device (such as 58) that transmits a DC power source (such as 03) and an alternating current signal from a first transmission line (such as trunk cable 1) consisting of a wire to a second transmission line (such as branch cable 2) also consisting of two wires. ), each having a first and second winding (such as 31, 32 and 33, 34) with an intermediate tap (such as dot, e, etc.) and wound in the same direction (such as 3). ), the intermediate taps (point b) of the first windings (31, 32) and the intermediate taps (point e) of the second windings (33, 34) are connected to the first transmission line, respectively. connecting each line of the second transmission line to the beginning of the first winding (point a, etc.) and the end of the second winding (point f, etc.), respectively; A capacitor (such as 4) is connected in series between the end of the first winding (such as point C) and the beginning of the second winding (such as point d).
Let j be connected.

[For use]

The coil function for direct current bypass is also built into the transformer.

【Example】

FIG. 1 shows an example of the configuration of a turnout 5A as an embodiment of the present invention. In the figure, a branch 5A connects a trunk cable 1 and a branch cable 2. A truss 3 including four windings 31 to 34 sequentially wound in the same direction is provided inside the turnout 5A. A point a at the beginning of the winding 31 and a point f at the end of the winding 34 are connected to two wires of the branch cable 2, respectively. Volume again! The end of the winding s31 and the beginning of the winding 32 are connected at a point 1, and the end of the winding 33 and the beginning of the winding 34 are connected at a point e. It is connected to the second wire of the trunk cable 1. Further, a DC blocking capacitor 4 is connected in series between a point C at the end of the winding 32 and a point d at the beginning of the winding 33. Also, in this example, the number of turns between the two points A and E connected to the trunk cable 1 (that is, the sum of the turns of windings 32 and 33) and the total number of turns connected to the branch cable 2 (that is, the sum of the turns of windings 31 to 34)
(total number of turns) is 1:,']. A DC power source (not shown) is transmitted between the main cable 1 and the branch cable 2 via the windings 31 and 34 of the transformer 3. Only the alternating current component of the signal from the trunk cable 1 passes through the capacitor 4 and the entire windings 31 to 34 of the transformer 3, and is transmitted to the branch cable 2 while being boosted three times. Conversely, the signal from the branch cable 2 is transmitted to the trunk cable l while being reduced in voltage by 1/Δ.

Effects of the Invention According to the present invention, the coil function for direct current bypass is built into the transformer, so the coil 25 in the conventional branching device can be omitted, and the number of parts can be reduced. When comparing the conventional turnout 5 and the embodiment turnout 5A, the number of electrical components is reduced from five to two.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing an example of the structure of a DC superimposed signal transmission system, and FIG. 3 is a conventional block diagram corresponding to FIG. 1.

Claims (1)

[Scope of Claims] 1) A branch that transmits a DC power source and an AC signal from a first transmission line consisting of two wires to a second transmission line also consisting of two wires, each having an intermediate tap, and a transformer having first and second windings wound in the same direction, and a middle tap of the first winding and a middle tap of the second winding are respectively connected to the first transmission line. connecting each wire of the first winding and the end of the second winding to each wire of the second transmission line; A branching switch for a DC superimposed signal transmission system, characterized in that a capacitor is connected in series between the beginning of the second winding and the beginning of the second winding.