JPH0218628B2 - - Google Patents

Description

[Detailed Description of the Invention] When a fault occurs in a communication facility consisting of an exchange in a switching center, in-house facilities at a subscriber's home, and communication lines connecting them, the following steps should be taken to remove the fault: Such work has been carried out in the past. That is, first, a worker goes to the subscriber's home and disconnects the line or uses a measuring device to determine the type of fault, or to determine the location of the fault, that is, whether the fault is occurring on the communication line. Work is currently underway to determine if the incident occurred at a residential facility. However, such work is time-consuming and causes delays in the removal of faults and, in turn, in the restoration of communication facilities.

SUMMARY OF THE INVENTION Therefore, the present invention makes it possible to clearly determine the type of failure and the location of the failure as described above while remaining in the exchange, thereby making it possible to speed up the restoration of the facility. The present invention aims to provide a failure detection device for communication facilities that are equipped with the following methods.

The drawings showing the embodiments of the present application will be described below. In FIG. 1, reference numeral 1 indicates a switching center. Among the equipment installed in this switching center 1, 2 indicates a well-known switchboard, and 3 indicates a well-known test stand. Next, 4 indicates the subscriber's home. In the in-house facility installed in the subscriber's house 4, 5 indicates an indoor wire, which is, for example, a wire laid from a safety device under the eaves of the house to various places indoors. Reference numeral 6 indicates in-house equipment, such as a telephone, a facsimile machine, and an answering machine. Next, 7 and 7 are a pair of communication lines, which are designed to interconnect the exchange 2 of the exchange 1 and the in-house facilities of the subscriber's house 4, and one end of them is connected to the exchange 2 and the other. The end is connected to a safety device at the subscriber's premises 4. In addition, this communication line includes wiring cables,
Includes distribution terminals and outdoor sheathed wire.

Next, the failure detection device will be explained. Reference numeral 11 denotes a control section, which is interposed between the communication line 7 and the subscriber's home facility. This control unit 11 is built into the safety device, for example. In this control section 11, D ₁ , D ₂ , D ₃ , and D ₄ are diodes, each of which is connected in series with the communication line 7 as shown. As is well known, these diodes have a threshold value as low as a few tenths of a volt, and also have a current capacity that can withstand not only communication current but also shock current caused by lightning, etc. It will be done. D ₅ indicates a varistor, communication line 7,
7 are connected to each other as shown in the figure. This varistor _D5 has a threshold value higher than that of the diode, for example, several hundred volts, and is also rated to withstand local battery voltage and lightning shock voltage. is used. In the circuit shown in FIG. 1, the varistor _D5 is connected closer to the communication line than the diode, but it may be connected closer to the household equipment 6 than the diode. Next, 12 indicates a detection section. In the detection section 12, 13 is a variable voltage power supply device, which is configured to be able to send out test power of variable voltage toward the communication line 7. Reference numeral 14 denotes a current detector, which is capable of detecting the value of the current of the test power supplied from the power supply device 13 to the line, and uses, for example, an ammeter. Reference numeral 15 denotes a voltage detector which is capable of detecting the voltage value of the test power sent from the power supply device 13 to the communication line, and for example, a voltmeter is used. 16 is a changeover switch, which includes switch elements 1 that operate in succession with each other;
6a and 16b. These switch elements 16a, 16b each have three switching terminals 1.
7, 18, and 19. These switching terminals 17, 18, 19 are connected to communication lines 7, 7 via exchange 2 or grounded, respectively, as shown in the figure.

Next, a fault detection operation by the fault detection device having the above-mentioned configuration will be explained. Generally, when some kind of failure occurs in a communication facility, the subscriber side notifies the switching center of the occurrence of the failure. When such notification is received, the switching center 1 operates the exchange 2 from the test stand 3 to connect to the home equipment 6 of the subscriber's home 4 where the above fault has occurred. After that, the detection unit 12 is used to determine the type of failure or the location of the failure. The determination is made as follows.

(1) First, both switch elements 16a and 16b of the changeover switch 16 are connected to their respective changeover terminals 17. In this state, the variable voltage power supply device 13
Testing power is sent out to both communication lines 7, 7 while changing the voltage from , and the values of the current and voltage respectively detected by the current detector 14 and the voltage detector 15 at that time are known.

When operating as described above, if a disconnection fault has occurred in the communication lines 7, 7, no current will flow even if the voltage is increased, as shown in FIG. 2A. In addition, if the disconnection fault occurs in the subscriber's premises 4, the second
As shown in Figure B, in the process of increasing the voltage as described above, when the voltage exceeds the threshold value _V1 of the varistor _D5 , the current increases rapidly.

On the other hand, if a short circuit or an insulation failure occurs in the communication lines 7, 7, if the voltage sent from the power supply 13 is increased, the current will increase as the voltage increases, as shown in Figure 3A. also rises linearly. In this case, if the point where the fault occurs is far from the switching center or the resistance value of the fault point is large, and the resistance value of the current flow path is large, the voltage and The characteristics of the current change are as shown in A in FIG. 3A. On the other hand, if the resistance value is close to the fault or the resistance value in the above-mentioned path is small, the changes in voltage and current will be as shown in (B) in the same figure. Also, if a short circuit or insulation fault occurs in the customer's premises, the current from the power supply 13 flows through the diodes D ₁ or D ₂ and D ₃ or D ₄ , so that the third As shown in FIG. B, when the value of the voltage sent out from the power supply device 13 exceeds the threshold values of those diodes, the current begins to increase rapidly. In this case as well, as in the case described above, the resistance values in the path through which the current flows are large or small as shown in A and B, respectively.

As mentioned above, the mutual relationship between the current and voltage values detected by the current detector 14 and voltage detector 15 changes depending on the type of fault or the location where it occurs, so it is important to check the changes. (Fig. 2 A, B and Fig. 3 A, B) The type of failure and its occurrence location can be accurately known.

(2) Next, when determining whether there is a ground fault or whether the fault is occurring on the line or in the subscriber's premises, both switch elements 16a in the changeover switch 16 ,16
b to one switch element (16a or 16
b) is connected to one communication line 7 and the other element (16
b or 16a) is connected to the switching terminal 18 or 19 so that it is connected to the ground. Then, similarly to the above, power for testing is sent out from the power supply device 13 toward the communication line 7 while changing the voltage.
In this case, if an earth fault occurs in either of the two communication lines 7, the power supply device 13
Since the electric power sent out from the communication line 7 flows to the ground via the communication line 7 and the place where the earth disturbance occurs, the current and voltage changes detected by the current detector 14 and the voltage detector 15 are as follows. becomes as shown in FIG. 4A. That is, the current increases linearly with respect to the voltage. In this case, depending on the distance from the exchange to the place where the earth's air is generated, or the degree of the earth's air, if the resistance value is large, it will be as shown in A, and if the resistance value is small. It becomes as shown in (b). On the other hand, when an earth disturbance occurs in the subscriber's premises, the power for inspection sent out from the power supply device 13 is transmitted to the communication line 7 and the diodes D ₁ , D ₂ or
Since the ground air flows through D ₃ and D ₄ to the point where it is generated, the relationship between the detected voltage and current is shown in Figure 4B.
It will be shown as follows. In this case as well, the relationship between voltage and current is as shown in A and B, depending on the resistance value, as described above. In the case of the above operation, by switching the changeover switch 16 to the changeover terminal 18 or 19,
It is possible to accurately detect an earth disturbance even if it occurs on either side of the real communication lines 7, 7 and the indoor wires 5, 5 connected thereto.

The above describes an example in which the type of fault and the location of the fault are determined by visually reading the voltage and current values, but when power is supplied for testing from the current device to the communication line as described above. Determine the value of the supply voltage when the current starts to rise (when it reaches several μA), and determine the value of that voltage (in the case of a disconnection fault, the current will flow if the disconnection location is on the communication line side). There is no voltage that varies,
Inside the house, the above voltage is 50 volts or more. In addition, in the case of short circuits and insulation failures, if the occurrence location is inside the building, the voltage is approximately 0.6 to 0.8 V or more, and if it is on the line side, it is less than the value inside the building. Furthermore, in the case of ground air disturbance, the place of occurrence is inside the house.
0.3 to 0.4V or higher, and lower than the value inside the building on the communication line side. ), a display device such as a lamp may be operated to display the type and location of the failure, respectively.

As described above, in this invention, the communication line 7
diodes D ₁ to _{D 4} between
and the varistor D ₅ having a threshold value higher than that of the diodes D ₁ to _{D 4} are respectively connected as described above, while on the side of the exchange 2, the communication line 7 is connected to a variable voltage test circuit. In addition to being able to supply electric power, it is also possible to detect the current and voltage values of the power for inspection, so if a problem occurs in the communication line 7 or in-house facilities, it can be done without leaving the telephone office. As described above, from the detected current value and voltage value.

(1) Determine the type of failure, such as whether the failure is a disconnection, a short circuit, or an insulation failure; and (2) Determine whether the failure is occurring in the communication line 7 or in the premises. This has the advantageous effect of making it possible to both determine the location of the failure and to facilitate smooth implementation of appropriate measures to deal with the failure.

[Brief explanation of drawings]

The drawings show an embodiment of the present application. Fig. 1 is a circuit diagram partially shown as blocks, and Figs. 2 to 4 show voltages and currents when the types of faults and their occurrence locations are different. A graph showing relationships. 2...Switchboard, 7...Communication line, 6...House equipment, 11...Control unit, _D1 , _D2 , _D3 , _D4 ...Diode, _D5 ...Varistor, 12...Detection unit, 1
3... variable voltage power supply device, 14... current detector,
15... Voltage detector.

Claims (1)

[Claims] 1. In a communication facility consisting of an exchange at a switching center, in-home facilities at a subscriber's home, and a pair of communication lines installed between them, a and a detection section connected to the pair of communication lines on the side of the exchange, and the control section is connected in series between each of the pair of communication lines and the premises facility. It consists of an intervening diode and a varistor connected between the two communication lines, and the varistor has a threshold higher than that of the diode, On the other hand, the detection unit includes a variable voltage power supply device capable of supplying test power with a variable voltage to the pair of communication lines, and a variable voltage power supply device that supplies test power with a variable voltage to the pair of communication lines. a current detector capable of detecting a current value of the flowing test power; and a current detector capable of detecting a voltage value of the test power applied from the variable voltage power supply device to the pair of communication lines. A fault detection device in a communication facility, characterized in that it consists of a voltage detector.