JPS5859637A - Orientating system for fault point - Google Patents

Abstract

PURPOSE:To set a folding connection from a repeator just before a faulty section so as to orientating a fault, by installing a relay for detecting feeding electric current and a hybrid coil to each repeator. CONSTITUTION:Each repeator consists of an incoming amplifier 3n, an outgoing amplifier 3m', and a power separating filter (PSF) 4, and numerous repeators are connected with each other by a coaxial cable 2. A direct current supplied from the starting end of the repeator group flows through the PSF 4 at the upstream side, a constant-voltage diode 5 which supplies a voltage across both terminals of the PSF 4, and a relay 7m. When the cable 2 connected to the downstream side is normal, the relay 7m operates and sets its contacts 8m and 10m to the ''OFF'' condition. When a fault occurs in the downstream cable 2, a folding connection is formed by the contacts 8m and 10m and the pulse of an echo tester supplied from a feeding point is folded through a hybrid H and, at the same time, a reflected wave from the fault is also folded, and thus, fault orientation can be made at the feeding point.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for locating a point of failure when power supply is cut off or a similar failure occurs in a communication transmission system that performs DC series power supply.

FIG. 1 illustrates an analog coaxial transmission system.

In the figure, 1 is a constant current source for power supply, 2 is a transmission line, and 31 to
3n, 31' to 3n' are repeaters, 4 is a power separating p-wave device that separates DC and signals (hereinafter referred to as PSF (Pow
Input 5, labeled er 8eparation Filter), is a constant voltage diode for supplying a constant voltage to the repeater. A signal relay device other than a transmission line, in this example a metal repeater, a PSF, and a constant voltage diode, is called a relay device. Reference numeral 6 denotes a feed turn transformer that transmits only signals and constitutes a loop for direct current. Currently, there are various types of transmission systems, but if you focus only on the power supply circuit, this is basically the type, although there may be some variations.

Now, in the system shown in Figure 1, if there is some kind of disconnection, for example, one of the transmission lines 2 is disconnected due to construction work, the power supply from the constant current source 11 etc. will stop, and all intermediate power supply will stop operating. do.

Therefore, since no information is obtained through the relay device, it is impossible to determine not only the location of the failure but also the disconnection between which relay devices.

In order to solve these problems, methods have been proposed for determining the faulty section of each stroke, but all of these methods only determine the faulty section, and do not determine the location of the fault. Can not. Conventionally, in order to determine the fault location, l
First, determine the faulty section, cut the faulty transmission line 2 at a relay installation installation station (hereinafter referred to as a relay station) that is in contact with the faulty location, and locate the faulty location from there by using the route route. Orient. This method is adopted.

However, since the introduction of solid-state electronic repeaters, the reliability of repeaters has improved dramatically, and not only are repeaters unmanned, but due to their transmission characteristics, relay stations are often located underground (inside manholes) or on main roads. Even if you try to enter the manhole to locate the fault point, it is often impossible during the day due to the necessity of traffic regulations, etc. Therefore, it takes time to determine the fault location, and the transmission line function is affected. The drawback is that recovery is delayed and the quality of communication services is affected.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a fault point locating method that easily locates a fault point immediately from a power supply station without having to go to an underground relay station or the like.

The failure point locating method of the present invention is a communication transmission method in which blood flow is serially supplied via a transmission line to a plurality of repeaters each having a power separation reactor installed on the input side and output side of a repeater. The medium-g device on the side includes current detection means for detecting a power supply current in a power supply line between the power separation P-wave device and the repeater on the output side and disconnecting the first and second switch elements. A series circuit of the first switch element and the resistor is connected to a power supply system on the input side of the repeater of the repeater in the opposite direction to the connection point of the current detecting means and the intermediate spinning machine. and the signal input side of the repeater on the transmitting side via the second switch element, and the pulse echo from the relay device adjacent to the fault point to the fault point is transmitted to the fault point. AJI is characterized in that the point of failure can be located by observing through the relay device. A relay 7m (
m = 1, 2 e..., n), and a circuit that connects the power supply side of the relay to the repeater power supply circuit of the reception @ (left-bound) transmission line via 8 m of contacts and 9 m of resistance of this relay. In addition, in the case where the section adjacent to the repeater is normal, the supply current causes the vreaer m to operate, opening the contact 8m and making it appear to be equivalent to the one shown in Figure 1. A hybrid coil H is inserted at the midpoint between the output side of 3m' and P8P4, and at the midpoint between the input side of repeater 3m' and PBr3, and furthermore, this hybrid coil H is a balanced wiring network BNW, and one terminal of is terminated. Furthermore, one terminal of each hybrid coil H on the repeater 3m and 3m' sides is connected to relay 7.
They are connected by a contact 10m which is released by the action of m. However, contacts gm and 10m are OFF due to relay operation.

In addition, the values of the relay current and resistance shall be selected appropriately so that the relay will operate even if there is only one relay section (i.e., two relays for transmission and reception) after it (right fill). .

With this configuration, first consider power supply under normal conditions.

Initially, each relay contact is ON, so when considering the start of power supply, the power supply current will be divided into each 9m resistor, but
The relay through which the largest current flows during the transition at the start of power supply is the one at the forefront, ie, 71. Therefore, the relay 71 operates continuously, and therefore the contact 81 becomes OFF. Next, the relay 82 of the next repeater operates, and the relays operate one after another until finally all contacts are turned off, and power is supplied in the same manner as in FIG. 1.

Next, consider failures such as power outages. Generally, when the power supply system is cut off or short-circuited, the constant current source for power supply (1 in FIG. 1) stops power supply to ensure equipment reliability. Now, suppose that a failure occurs 3 meters behind the repeater. At this time, if the maintenance personnel discovers that the power supply is interrupted, they try to forcibly supply power using a constant current power supply. At least 3 repeaters (m-1
), the relay operates as described above and power is supplied. However, with a 3m repeater, no current flows through the relay. Therefore, the relay 7m does not operate, and the power supply current remains looped back through the resistor 9m. In other words, due to a disconnection fault, the 3m repeater was automatically or manually removed.

The power supply becomes a loop at 3 ml. In this state, the maintenance person connects the pulse sending section of the pulse echo tester to the input of the transmitting amplifier at the cable or sending end from the location where the power feeding device is located, and connects the receiving section of the pulse echo tester to the output of the receiving amplifier. The output pulse waveform of the pulse echo tester is determined by considering the section length of the relay transmission line to be measured, the repeater interval, the upper and lower frequency limits of the repeater, the overload point of the repeater, etc. When a signal is sent to the transmission side of the transmission line, it is relayed one after another by each repeater and finally reaches the output side of the repeater 3m immediately before the faulty section. However, as already mentioned, the output side of the repeater 3m and the input side of the repeater 3ml are connected through the hybrid coil and the contact 10m (in other repeaters, the contact 10i is disconnected). The 71 iplied coil on the output side of the repeater 3m has an infinite amount of attenuation between the output of the repeater 3m and the input of the repeater 3m'' in an ideal balanced state, but at It is assumed that the balance between the two repeaters is disturbed and the leakage is equal to the amount of narrowing of the transmission line in one repeater section.If this amount of attenuation is NdB, the output pulse of the repeater 3m has an attenuation of N+3dB. After receiving it, it reaches the input of the repeater 3m' and is then relayed on the receiving side transmission line and returns to the receiving point of the pulse echo tester.However, 3 dB is the input of the repeater 3m'.
7. This is the loss of the hybrid coil on the side.

On the other hand, the noise output from the 3m repeater has a loss of 3 dB to the downstream transmission line, and propagates to the line side.However, since the line is disconnected, the noise does not propagate along the line. (Russ is reflected with a reflection coefficient of approximately 1, but the loss of the hybrid coil for the reflected wave is only 3 dB, and the reflected pulse is transmitted to the repeater 3 m' through the contact point 10 m.) Thus, one pulse is received after a certain time ω from the time when the pulse was sent from the pulse echo tester, and then a short time (
After Δt), another signal will be received.If this situation is plotted on a cathode ray tube, an image as shown in Fig. 3 will be obtained.From this image, T.

By determining Δt, the position of the repeater immediately before the failure point and the position from this repeater position to the failure point can be determined. The method for determining this is well known and will be omitted here, but in an echo pulse tester, the time from the trigger input to the start of the sweep is made variable, and the image is moved to an arbitrary location by manipulating the delay time. By replacing delay time with distance, distance can be directly connected.

In FIG. 3, the leftmost pulse is the sending pulse, the middle pulse is the turning pulse at the repeater, and the rightmost pulse is the reflected pulse on the line. The presence of undersheets in the middle and rightmost pulses is due to the direct current cut, but there is no particular problem. The difference in height between the middle pulse, that is, the aliased pulse at the aborter, and the rightmost pulse, that is, the reflected pulse at the fault point, is that even if the reflection coefficient at the fault point is 1, the height is different between the middle pulse and the next repeater. This is an example of what happened because the point is a little far away and the amount of attenuation on the round trip to the point of failure is greater than the amount of attenuation N of the folded pulse mentioned above.

As described above, according to the present invention, the fault location can be easily and accurately located, which greatly improves the quality of service in terms of maintenance.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a general coaxial cable transmission system, Fig. 2 is a circuit showing an embodiment of the present invention, and Fig. 3 is a waveform showing an example of an image obtained by a pulse echo tester in Fig. 2. It is a diagram. 1... Constant current power supply for power supply, 2... - Transmission line, 31° 31', 32, 32' 3n, 3n',
3m, 3m'...Repeater, 4...P8
F, 5... Constant voltage diode, 71°7m...
...Relay, 81.8m, lQm...Contact that breaks due to relay operation, H...Hybrid coil, BNW...Balanced wiring network, T ...
... Pulse round trip propagation time from the test station to the relay station immediately before the fault section, Δt ... Pulse round trip propagation time from the relay station immediately before the fault section to the fault point.

Claims (1)

[Claims] In a communication transmission system in which DC series power is supplied to a plurality of relay devices provided with power separation Pa1d devices on the input side and output side of the repeater via an I transmission line, the relay device on the transmission side is connected to the power separation r on the output side. the first switch element is configured by inserting in series a current detection means for detecting the power supply current and disconnecting the first and second switch elements in the power supply line between the wave transmitter and the repeater; A series circuit consisting of a resistor and a resistor is connected between the connection point of the current detection means and the repeater and the power supply line on the input side of the repeater located in the opposite direction, and The signal output side of the repeater on the transmitting side and the signal input side of the repeater on the receiving side are coupled via A fault point locating method characterized in that a fault point can be located by observing through a relay device.