JPS6358415B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an underground cable line for transmitting telephone signals or control signals between both ends of the line or between an end and an intermediate section using an underground cable line. This relates to the communication method used.

BACKGROUND OF THE INVENTION In overhead power transmission lines, power line carrier telephones have been put into practical use for telephone communication between substations, power plants, and control stations provided at the terminal and intermediate points of the line, and for controlling electrical equipment. As shown in FIG. 1, this method connects the conductor 1a of the line 1 and the grounding line 3 via a coupling capacitor 2 between two points on the overhead power transmission line 1.
Connect the transmitter/receiver 4 between them and send several watts at 100 to 300KHz.
It is used to conduct telephone signals or control signals by passing current as a carrier current of about 100 mL. Note that 5 indicates a transformer coil, and 6 indicates a blocking coil.

Most underground cable lines pass underground in urban areas, have a relatively short length, and have a large attenuation to the signal current of the line.
Currently, it has not been put into practical use due to the large scale of equipment such as coupling capacitors.
However, in recent years, in the event of an accident on an underground power distribution line, switching operations are instantaneously determined based on the magnitude, direction, operating time, etc. of the fault current, such as the ground fault current. Attempts have been made to use signal currents. In addition, there is an increasing demand for telephone communication between substations and power receiving stations, or between substations and power receiving stations, and construction sites at midpoints of railway lines.

The object of the present invention is to meet the above-mentioned needs by coupling a current transformer to the grounding point of an underground cable line or cable shielding layer without touching the high-voltage side of the underground cable, and transmitting circulating signals between the shielding layers. Pass a current,
The purpose is to provide a communication method using an underground cable line that enables safe and reliable communication. A circulating circuit is formed by connecting the metal shielding layer and the connecting wire to each of the metal shielding layers of the railway line, and a current transformer connected to a transmitter/receiver is installed at at least two places in the circulating circuit, and the circulating circuit is completed. A toroidal iron core is attached to the existing connection line between the metal shielding layers to be short-circuited, and the signal current induced in the circulation circuit by the one current transformer is received by the other converter, and communication is established between the transmitter and receiver. This method is characterized in that it performs the following steps.

The method according to the present invention will be explained in detail based on the embodiment illustrated in FIG. 2 and below.

Now, it is assumed that communication is performed between the near end X and the far end Y using the cable 10 installed between the near end X and the far end Y. Metal shielding layers 11b, 11c of cables 10b, 10c laid in parallel with metal shielding layer 11a of a selected cable 10a
Connecting lines 12x and 12y are wired between the near end X and the far end Y, respectively. This connection line 12
Generally, x and 12y are already wired and grounded by a grounding wire. Therefore, since the shielding layer 11a and the shielding layers 11b and 11c are connected at the near end X and the far end Y, a circulation circuit is formed. Therefore, a current transformer 13 or 13' is installed around the cable 11a at the near end X or around the connecting line 12x, and the transmission
The receiver 14 generates a signal current i consisting of a voice signal and a control signal in the circulation circuit. That is, when a current is passed through the current transformer 13 or 13' by the transmitter/receiver 14, a signal current i is induced in the shielding layer 11a or the connecting wire 12x by the electromagnetic induction effect of the current transformer 13 or 13'. This current i passes through the shielding layer 11a of the cable 10a from the near end X to the far end Y, reaches the far end Y, passes through the connecting wire 12y, and further passes through the shielding layer 11b of the other cables 10b, 10c.
11c, and then circulates in the circulation circuit from the connection line 12x at the near end X back to the current transformer 13' or 13 position. Therefore, at the far end Y, around the cable 10a or the connecting wire 12y
If a current transformer 15 or 15' is attached to the current transformer 15 or 15' and the signal current i is detected by the transmitter/receiver 16 connected to the current transformer 15 or 15', the signal from the near end X is transferred to the far end Y. can be received. Also, far end Y
Communication from to near end X is possible by completely reversing the transmission and reception of signals. In these cases, the signal current i mainly passes through the shortest circulating circuit, and most of the signal current i goes to the lines 10a', 10b', and 10c', which are further away from the near end
will not flow, and the signal current i will not flow on the unnecessary line.
It has the advantage of not having to flush. Also, in order to enable transmission and reception with the near end X or the far end Y at the midpoint between the near end X and the far end Y, the cable 10 at the midpoint
a, 10b, 10c shielding layers 11a, 11b, 1
A current transformer 17 may be attached to one of the terminals 1c and communication may be performed using a transmitter/receiver 18. Current transformers 13, 13', 15, 15', 17 used for transmitting and receiving these
For example, as shown in FIG. 3, a coil 20 is wound around an annular iron core 19, and both ends 2 of this coil 20 are
1 and 22 are connected to transmitter/receivers 14, 16, and 18. Cable 10 or connection wire 12
x, 12y must pass through the center of the iron core 19, and the iron core 19 can be split into two if necessary.
It may be possible to attach it from around the cable 10 or the connection wires 12x, 12y that have already been wired.

Moreover, the shielding layer 11a, 1 at the midpoint of the cable 10
When communicating between the near end
A toroidal iron core with extremely high magnetic permeability is inserted into the connecting wire between 1a and 11b to increase the impedance of the connecting wire to high frequencies, and to prevent the signal current i from flowing through this connecting wire. Furthermore, as shown in FIG. 4, when communicating between two or more sections, that is, between an end Z further away than the far end Y and the near end X, the connection line 12y between the shielding layers 11a and 11b of the far end Y The above-mentioned toroidal iron core 23 is inserted into the cables 10a and 10a', which are connected to each other at the far end Y, and current transformers 24 and 25 are attached to the cables 10a and 10a', respectively.
By electromagnetically coupling the cables 4 and 25, the signal current i can be passed through the metal shielding layer 11a' of the cable 10a' and transmitted to the far end Z. Therefore, at the end Z, it is sufficient to communicate with the near end X using a current transformer and a receiver (not shown).

The advantages of the communication method using the underground cable line according to the present invention are listed below.

(1) It is possible to configure a circulation circuit without touching the high voltage terminal of the cable, regardless of the presence or absence of power supply, and it is possible to safely install, remove, and maintain transmitters and receivers.

(2) Since the communication line is a structurally strong power cable line, there are fewer line failures and high reliability.

(3) Since it is separated from the power circuit by a current transformer, it is effective in suppressing surge voltage generated in the power circuit.

(4) Communication is possible not only between the terminal ends of the cable, but also with any intermediate part of the cable.

(5) Circulation circuits can be configured for specific sections, eliminating the need for signal current to flow in unnecessary sections. It is also possible to flow a signal current in an arbitrary section only between two specific points.

(6) Cost is low because no expensive high-voltage capacitor is required.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional communication method using an overhead power transmission line, and FIG. FIG. 3 is a perspective view of the current transformer, and FIG. 4 is a configuration diagram of a circuit for communication over two or more sections. Symbols 10, 10a, 10b, 10c are cables, 11a, 11b, 11c are metal shielding layers, 12
x, 12y are connection lines, 13, 13', 15, 1
5', 17, 24, 25 are current transformers, 14, 16,
18 is a transmitter/receiver, and 19 is an iron core.

Claims (1)

[Claims] 1 At both ends of any line of the cable, the metal shielding layer of that line is connected to the metal shielding layer of another parallel line to form a circulation circuit with the metal shielding layer and the connecting wire, and the circulation circuit is Attach current transformers connected to transmitters and receivers at at least two locations in the circuit, attach a toroidal iron core to the existing connection line between the metal shielding layers that short-circuits the circulating circuit, and use one of the current transformers to short-circuit the circulating circuit. A communication method using an underground cable line, characterized in that the signal current induced in the current transformer is received by the other current transformer, and communication is performed between the transmitter and receiver.