JPS5923506B2 - Fault isolation detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fault separation detection method for separately detecting a fault in a private subscriber line and a fault in a network.

In a telephone exchange system, a subscriber line may become defective due to a disaster or some other condition, which may cause a large number of pseudo calls to occur simultaneously.

When the exchange detects such pseudo calls and normal normal calls, it controls the connection between the subscriber and the calling register trunk via the network. When this happens, a communication line continuity test is performed, and if a continuity failure is detected, the bus information used is typed out and recorded for maintenance purposes. Therefore, when a pseudo call occurs as mentioned above, it is determined that there is a continuity failure because the subscriber loop is not completely formed, and it is not a network failure.
Bus information used is typed out, leading to confusion during maintenance. In order to avoid such drawbacks, conventionally only the originating register trunk has been provided with a special configuration for determining whether the fault is with the subscriber line or the network.

For example, as shown in FIG. 1, when the subscriber and the subscriber line are represented by resistance Rs and are connected to the outgoing register trunk ORT via the network NW, a communication path continuity test is performed. In addition, LR is a relay of the subscriber circuit, A is a relay of the originating register trunk ORT, and Rx is a contact of a control relay (not shown), and the high resistance Rx is short-circuited by the contact during the communication path continuity test. ing. Therefore, the determination of poor continuity is generally made based on the logic that ``relay A is inoperative, and relay LR of the subscriber circuit is in operation.''

Therefore, if there is a conduction failure between fB on the network NW corresponding to the B line of the A line and the B line, the current IA on the A line side will flow when the A line side is in a normal conductive state. The current flowing through relay LR will not flow, and it will not be determined that there is a continuity failure. Therefore, when relay A is not operating, the control relay is operated, the contact is opened, and a high resistance Rx is inserted to reduce the current IA, creating a highly sensitive circuit configuration that enables detection of high resistance earth. Current ILR・＞1LR=
Make it 1-1A.

In this case, the current of 1 A becomes a negligible value due to the insertion of a high resistance, so that it is possible to detect a continuity failure by forming a state in which relay LR is operating and relay A is not operating. On the other hand, if a continuity failure occurs between the FAs on the network NW corresponding to the A line and the B line is in a conductive state, the relay LR will operate, so whether or not the contact t is opened by the operation of the control relay is determined. It is possible to detect continuity defects regardless of the situation.

In this way, a continuity test is performed by connecting to 0RT when a call is made to determine continuity, so a control circuit and a high-resistance insertion circuit are provided only for 0RT, and such a control circuit and Continuity tests are not performed on other trunks that do not have high resistance insertion circuits.

The object of the present invention is to enable separate detection of faults between connected shore lines and networks without the need for the aforementioned control circuits or high-resistance insertion circuits. The purpose of this is to prevent information from being typed out as if a failure had occurred even though there is no network failure such as a failure in a sleepy subscriber line.

Examples will be described in detail below. FIG. 2 is an explanatory diagram of the main parts of the embodiment of the present invention, where the same reference numerals as in FIG. is the first contact point of the cutoff relay, and is the first contact point? The state of R and a is determined by the central controller CC.
is read by scanning.

If the communication path continuity test results in poor continuity, contact CO is made to allow current to flow through relay LR in the subscriber circuit. At that time, the total resistance on the side of the A line 1a flowing through the network side in the figure is Ral, the resistance of the path of the current 1b flowing through the relay LR is Rb, and the resistance of the subscriber line R
s, network NW (7) If the total resistance including the resistance on the B line side and the resistance connected via the contact CO of the cut-off relay is R, then the equivalent circuit derived from the actual circuit configuration is shown in Figure 3. It will be as shown below. Here, the loop current flowing to the subscriber side is B,a●Rbl=E/[R+1--±)].

Note that E is the 112.4-Rh power supply voltage.

Therefore, each current A, Ib is expressed by . Therefore, when it is determined that there is a continuity failure, if the current 1b is larger than the current of relay LR and relay LR operates, it is determined that there is a failure in the network NW when the scanning result of the subscriber circuit is in an off-hook state. Ru.

That is, the current 1'b becomes large because the network NW has poor continuity and the resistance Ra is large. That is, by comparing the shunt current values A, Ib with the sensing current values of each relay A, LR, it is possible to detect whether a fault has occurred in the subscriber line or in the network. Also current,
When current 1a is below the moving current of relay A, relay A is inoperative, but at this time, when current 1b is below the moving current of relay LR, relay LR is also inoperative. Therefore, in this case, if the subscriber is off-hook, it can be determined that there is a subscriber line failure, but the subscriber is excluded from the failure detection target of the network NW. In other words, it can be considered that the subscriber is in the same state as on-hook. The points to be noted in the present invention are:
During a pseudo call, when the communication path of the network NW has not been formed and the current value of the relay LR that detects the call is almost equal to the detection threshold, the continuity test after connecting to 0RT will naturally detect continuity. Defective (Generally, touching current is relay LR
(relay A is larger than that), and the network NW
When a fault is detected in the cut-off relay, the relay LR is connected through the contact CO of the cut-off relay, and the current is shunted to the relay LR. Since the current shunted in this way is smaller than the current flowing through relay LR, this relay LR becomes inoperable, and it can be assumed that the subscriber is on-hook (which is actually on-hook in many cases); At least it will not be regarded as a failure of the network NW. Fault isolation detection as described above is performed using contacts A and f.
The state of r can be programmed in the central controller CC by scanning. In the above-mentioned embodiment, when a subscriber and a calling register trunk are connected via a network by detecting a call, when a continuity test is performed and it is determined that there is poor continuity, the relay LR in the subscriber circuit and the calling register trunk are connected to each other via a network. A circuit is formed in which current is shunted to relay A of the register trunk 0RT, and by allowing more current to flow to the relay on the side with no continuity failure, it is possible to detect whether a failure has occurred in the subscriber line or the network. This eliminates the need for a control circuit or a high-resistance insertion circuit as in the conventional example.

Therefore, even when connected to a trunk other than the originating register trunk, the present invention can be applied to perform fault isolation detection when a continuity failure occurs. As explained above, the present invention (when it is determined that there is a continuity failure as a result of the main line continuity test), the loop current flowing on the subscriber circuit side (the loop current flowing in the subscriber circuit side) is transmitted to the relay LR of the subscriber circuit and the relay A of the trunk. Connect the relay LR of the subscriber circuit to the line on the subscriber side via the contact CO of the cut-off relay so that the current is shunted to the subscriber circuit, identify whether the relay LR of the subscriber circuit operates, and When LR is inactive, network N
When the relay LR operates instead of a fault in W, it is determined that the fault is in the network NW, and subscriber line faults and network NW faults can be detected separately.

Therefore, there is no need for a control circuit or a high-resistance insertion circuit as in conventional systems, so fault isolation and detection is possible even when connected to various trunks other than the transmitting register trunk, which improves the operational efficiency of the switching system. Reliability can be improved. In addition to being carried out by the program of the central control unit CC, fault isolation detection can also be carried out by the hardware configuration of the marker in the crossbar exchange.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of conventional separation detection of subscriber line failures and network failures, FIG. 2 is an explanatory diagram of an embodiment of the present invention, and FIG. 3 is an equivalent reprint of FIG. 2.

Claims (1)

[Claims] 1. When a subscriber and a trunk are connected via a network, in a switching system that performs a call path continuity test, if a continuity failure is determined as a result of the call path continuity test, the subscriber's Connecting the relay of the subscriber circuit to the line on the subscriber side via a contact point of a cut-off relay so that the loop current flowing in the line is divided into the relay of the subscriber circuit and the relay of the trunk, A failure isolation detection method characterized in that when a relay in the subscriber circuit is inoperative, it is not determined to be a failure in the network, and when a relay in the subscriber circuit is activated, it is determined to be a failure in the network.