GB1565489A

GB1565489A - Method of and apparatus for locating faults in a centrally controlled electrical system

Info

Publication number: GB1565489A
Application number: GB17634/78A
Authority: GB
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1977-06-27
Filing date: 1978-05-04
Publication date: 1980-04-23
Also published as: IT1096009B; IT7824721A0; FR2396483A1; ZA782945B; DE2728942C2; DE2728942B1; NL7806895A

Description

(54) METHOD OF AND APPARATUS FOR LOCATING FAULTS IN A CENTRALLY CONTROLLED ELECTRICAL SYSTEM (71) We, SIEMENS AKTIENGESELL SCHAFT, a German Company, of Berlin and Munich, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a method of and apparatus for determining the location of faults in centrally controlled electrical systems such as telecommunications systems, in particular in telephone exchange systems, in which there are at least one central device and a plurality of peripheral units and wherein fault indications are analysed on the occurrence of faults whose location is not immediately obvious.

In telecommunications systems, in particular in telephone exchange systems, it is necessary to determine the origin of any faults as rapidly as possible. Rapid determination of the fault location facilitates a rapid elimination of the fault so that the operation of the telecommunications system can be as free as possible from interruption and disturbance.

Processes for automatically reporting the location of faults in telecommunications systems are already known.

German Specification No. 1118 274 discloses a process for automatically determining the location of faults which occur in a communication-processing system consisting of a plurality of peripheral units and at least one central device. One of the characteristics of this known process is that in the event of a fault message which does not indicate the fault location and which continues for such time as the fault origin is active, the peripheral units are automatically cut off (and then possible reconnected) at their connections to the central device using contacts controlled by a central monitoring device in a previously determined sequence.The disappearance (or recurrence when reconnection is effected) of the fault messages is employed as an indication of the location of the fault and in all cases the process is terminated when the unit which has just been switched in or out of the system is established as the fault location. This process is referred to herein as a fault localisation process.

Another characteristic of this known process consists in that if the fault message has not disappeared when the other peripheral units have been cut off and two integers remain connected to one another (a peripheral unit and the central device) that integer whose withdrawal from the system would result in the lesser impairment to the functioning of the system is reported as being the fault location.

This known process permits the determination and simultaneous disconnection of a faulty unit in a straightforward manner. However, the process requires a considerable component outlay in the form of connecting relays and disconnecting relays.

Furthermore, this known process involves the disadvantage that the connection and disconnection procedures required to discover a fault location can, on occasion, impair the sensitivity of a telecommunications system. This can be particularly disturbing in real time systems such as telephone exchange systems. Also spontaneous fault localisation is often pointless because as a rule the process cannot occur until a faulty function has been completed.

According to one aspect of this invention there is provided a method of locating faults in an electrical system comprising a central device to which is connected a plurality of peripheral units, said method including the steps of storing data respectively relating to the peripheral units and comprising information concerning the number of fault indications associated with the respective unit on a probability basis, evaluating the stored data at intervals to determine when the number of fault indications exceed a predetermined threshold for any one of a plurality of sets of one or more of the units, said sets being respectively associated with function zones of the system, and instigating a fault localisation or rectification process when said stored data evaluation indicates that one function zone or a group of function zones it, to a predetermined degree of probability, faulty.

According to another aspect of this invention there is provided apparatus for locating faults in an electrical system comprising a central device to which is connected a plurality of peripheral units, said apparatus including a store having storage positions respectively allocated to said peripheral units each said storage position being arranged for receiving data relating to the number of fault indications associated with the respective unit on a probability basis, means for evaluating the stored data at intervals to determine when the number of fault indicaitons exceeds a predetermined threshold for any one of a plurality of sets of one or more of the units, said sets being respectively associated with function zones of the system, and means for providng a control signal for instigating a fault localisation or rectification process when said stored data evaluation indicates that one function zone or a group of function zones is, to a predetermined degree of probability, faulty.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: - Fig. 1 is a block circuit diagram of a telecommunications systems to which this invention can be applied; Fig. 2 is a block schematic diagram of a data store for use in fault locating apparatus embodying this invention and used with the system shown in Fig. 1; and Fig. 3 is a block circuit diagram of the fault locating apparatus using the data store shown in Fig. 2.

Referring to Fig. 1, there is shown a hierarchical telecommunications system to which this invention can be applied. The system comprises a central device STZ, a central line system LZ, a plurality of superordinate peripheral units STP1, STP2 . .

a plurality of peripheral line systems LP1, LP2 . . and a plurality of peripheral units arranged in sets lPl, 1P2 . . . lPn and 2P2 . . . 2Pn associated with the superordinate devices STP1 and STP2 respectively to form function zones FB1, FB2 of the system.

This type of hierarchical construction for a telecommunicaions sysems is expedient, for example, with centrally controlled telephone exchange systems which are preferably computer controlled. An example of a telephone exchange system to which the invention can be applied possesses, function zones comprising up to eight peripheral units (such as lPl . . . 1P8 in the system shown in Fig. 1) which are each provided singly orWepending on their operational significance-in duplicate. The superordinate units and the peripheral line systems are generally provided in duplicate.

The same applies to the central device and the central line system.

In known manner, this type of construction facilitates the substitution of units which are faulty. In this embodiment it is arranged that substitution of faulty units takes place as a result of a data evaluation indicating that a particular unit or set of units probably comprises the faulty function zone. In place of substitution-if permitted by the work load of the relevant telecommunications system-following the determination of a probable faulty function zone a switchover can be made from working operation to test operation wherein the units under consideration are selectively called up. The units normally remain passive during their test call-ups of this kind.

Referring to Fig. 2, part of a fault locating apparatus for use with the system shown in Fig. 1, has a configuration store KSP comprising an input register ER, an output register LR and storage positions SSP which are classified in accordance with the hierarchical construction of the associated telecommunications system. The storage positions are respectively allocated to the peripheral units P and STP shown in Fig. 1.

Referring to Fig. 3, the fault locating apparatus shown includes the configuration store KSP, a NOR-gate NG a decoder DEC whose outputs are connected to switching means comprising logic-linking elements G and threshold value elements SG.

Fault indications or messages FM from the telecommunications systems are input into the configuration store KSP. Data signals indicative of whether or not the respective peripheral unit is in use in the operation of the system are also received by each storage position of the store KSP.

For such time as an electrical signal representing a fault message FM is present, the output of the NOR-gate NG emits a signal having the binary value L, as a result of which the decoder DEC is deactivated. Not until the relevant fault message FM ceases does a signal having the binary value H appear at the output of the NOR-gate NG as a result of which the decoder DEC is activated. Statement signals concerning the prevailing operating state of the telecommunications system are supplied in coded form from the outputs of the configuration store KSP. The outputs of the decoder DEC are connected respectively to the inputs of logic-linking elements G or to inputs of threshold value elements SG.

These logic-linking elements and threshold value elements each possess an additional input ZE via which commands B can be input in the form of binary signals.

Threshold values can be established in the threshold value elements SG by means of control signals S via a subsidiary input.

In accordance with the number of out out signals supplied via the outputs of the decoder DEC and their configuration and in dependence upon the command signals supply via inputs ZE various output signals appear at the outputs of the logic-linking elements G and threshold value elements SG. Thus for example a signal LV which initiates a fault localisation process or a signal AB which initiates the disconnection or substitution of units and herein generally referred to as fault rectification, are provided.

The threshold values S of the threshold value elements SG can be varied over a range of values by means of the signals S so that the reaction thresholds, representing respective different numbers of received fault indications, can be readily matched to the work load and capacity of the telecommunications system.

Thus, in accordance with the requirements or operating situation of the telecommunications system, processes, such as for example fault localisation processes, disconnections, substitutions etc. can be controlled in a simple fashion.

As a further refinement, the peripheral units can contain self-checking devices and can be individually called up for regulating or test purposes and arranged to emit positive messages which indicate that the particular called-up unit, the superordinate unit for the relevant function zone, and the related circuits located in the test path of the various line systems are free from faults. It can be arranged that units which do not emit any such positive "fault-free" messages within a predetermined period of time and/or do not receive a regulating call signal or test call signal within a predetermined interval of time, are automatically disconnected from operation and subsequently emit a fault message. This can be achieved in a simple manner by means of timing elements provided in the respective units.

This development is advantageous in as much as it facilitates a constant monitoring of the individual units in a telecommunicaitons system even during operationally slack periods when function faults might not be apparent.

A further development is characterised in that of a plurality of possibly faulty units that unit whose withdrawal from operation would result in the least impairment to the functioning of the telecommunicaitons system is designated as being faulty.

Since fault messages occurring in complex telecommunications systems, such as for example telephone exchange systems, are generally ambiguous in respect of their original, it is advantageous to examine first and possibly disconnect first that unit which has the least significant effect on the operation of the system.

Another further development is characterised in that units regarded as causing fault indications can be assigned a fault statistical significance in accordance with their degree of functional importance in that items of data representing two or more fault messages are written into the configuration store for each actual fault message received.

An advantageous feature of this further development consists in that identical evaluation processes can be used for units assigned different significance values.

In a yet further development stored items of data representing fault messages are automatically erased from the configuration store after a given period of time if no further fault messages of the same type have been received within the given time period. This ensures that fault messages produced by sporadic faults can be eliminated from the statistical evaluation. Thus faults which are caused for example by atmospheric discharge between subscriber lines, temporary changes in potential due to measuring or checking operations and the like can be ignored.

Similarly, by ensuring that only after reception of a predetermined minimum number of fault messages of the same type does an appropriate reaction take place, the effect of sporadic faults in the evaluation can be minimised. To achieve this, it is only necessary to provide passive reaction thresholds.

The embodiments described above offer the advantage that on the occurrence of a fault message it is unnecessary spontaneously to run a fault localisation process. The coarse localisation effected prior to any localisation process which may be required enables the localisation process itself to be handled with a low outlay, achieving an advantageous economy of storage positions and running time. The reduction in running time results in the fact that the operation of the relevant telecommunications system is impaired only to a small extent more tolerable than with conventional systems.

The embodiments described above also have the advantage that statements concerning the relevant operating states can be obtained passively, i.e. without the need for a special evaluation process and with at low time outlay. The operating reliability of such a centrally controlled arrangement is thought to be particularly good.

WHAT WE CLAIM IS: - 1. A method of locating faults in an electrical system comprising a central device to which is connected a plurality of peripheral units, said method including the steps of storing data respectively relating to the peripheral units and comprising information concerning the number of fault indications associated with the respective unit on a probability basis, evaluating the stored data at intervals to determine when the number of fault indications exceeds a predetermined threshold for any one of a plurality of sets of one or more of the units, said sets being respectively associated with function zones of the system, and instigating a fault localisation or rectification process when said stored data evaluation indicates that one function zone or a group of function zones is, to a predetermined degree of probability, faulty.

2. A method according to Claim 1 wherein said stored data evaluation is carried out immediately following reception of each fault indication.

3. A method as claimed in Claim I or Claim 2 wherein of a plurality of said peripheral units suspected as faulty that unit whose withdrawal from operation would result in least impairment to the operation of the telecommunications system is recorded as being faulty.

4. A method as claimed in any one of the preceding Claims wherein fault indication storage for the respective units is effected in dependence on their degree of functional importance in that items of data representing two or more fault indications are stored for each actual fault indication received, the number of fault indications stored per actual fault indication received being dependent on the degree of import ance attached to the relevant unit.

5. A method according to Claim 4 where in identical data evaluation are effected for the units whose number of fault indica tions stored per actual fault indication re ceived depends on the functional import ance of the relevant unit.

6. A method as claimed in any one of the preceding Claims wherein items of stored data representing fault indications are automatically erased after being stored for a predetermined period of time if no further such fault indications have been received in said time period, whereby fault indications resulting from sporadic faults, are eliminated from said evaluation.

7. A method as claimed in any one of Claims 1 to 5 wherein only after reception of a predetermined minimum number of fault indication evaluation results of the same type is an appropriate reaction provided whereby fault indications resulting from sporadic faults are eliminated from said evaluation.

8. A method as claimed in any one of the preceding Claims wherein, when the units are functioning correctly and ready for operation, they automatically emit positive messages at predetermined intervals of time employing self-checking devices contained within the units and the units emit a fault indication if they have not emitted a positive message within a pre determined period of time.

9. A method of automatically determining the location of faults in a tele communications system, which has at least one central device and a plurality of peri pheral units arranged in a hierarchy with function zones of the system being defined by groups of peripheral units, each group having a superordinate unit, said method including writing items of data which repre sent fault indications and the probable originals of the fault messages into a con figuration store which has storage positions respectively assigned to the units and which each contain items of information con cerning the state of the telecommunications system in the form of statements on whether or not the respective unit is in use in the operation of the system, statistically evaluating the contents of the configuration store following each writing-in pro cess in accordance with the number and probable locations of origin of the fault indicaitons which have so far occurred, when a predetermined minimum number of fault indications is evaluated to corre spond to locations of fault origin in a function zone of the system, recording the superordinate unit of this function zone as being faulty, and supplying a control signal which instigates a fault localisation process when a superordinate unit of one or more function zones necessary for system operation is faulty to a sufficient degree of pro bability.

10. A method of locating faults in an electrical system comprising a central de vice to which is connected a plurality of peripheral units, said method being sub stantially as described herein with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. storage positions and running time. The reduction in running time results in the fact that the operation of the relevant telecommunications system is impaired only to a small extent more tolerable than with conventional systems. The embodiments described above also have the advantage that statements concerning the relevant operating states can be obtained passively, i.e. without the need for a special evaluation process and with at low time outlay. The operating reliability of such a centrally controlled arrangement is thought to be particularly good. WHAT WE CLAIM IS: -

1. A method of locating faults in an electrical system comprising a central device to which is connected a plurality of peripheral units, said method including the steps of storing data respectively relating to the peripheral units and comprising information concerning the number of fault indications associated with the respective unit on a probability basis, evaluating the stored data at intervals to determine when the number of fault indications exceeds a predetermined threshold for any one of a plurality of sets of one or more of the units, said sets being respectively associated with function zones of the system, and instigating a fault localisation or rectification process when said stored data evaluation indicates that one function zone or a group of function zones is, to a predetermined degree of probability, faulty.

11. Apparatus for locating faults in an

electrical system comprising a central device to which is connected a plurality of peripheral units, said apparatus including a store having storage positions respectively allocated to said peripheral units each said storage position being arranged for receiving data relating to the number of fault indications associated with the respective unit on a probability basis, means for evaluating the stored data at intervals to determine when the number of fault indications exceeds a predetermined threshold for any one of a plurality of sets of one or more of the units, said sets being respectively associated with function zones of the system, and means for providing a control signal for instigating a fault localisation or rectification process when said stored data evaluation indicates that one function zone or a group of function zones is, to a predetermined degree of probability, faulty.

12. Apparatus according to Claim 11 and arranged to carry out a method according to any one of Claims 2 to 9.

13. Apparatus for carrying out a method according to any one of Claims 1 to 9 wherein respective outputs of storage positions or of a read-out register of a configuration store of the apparatus are connected to respective inputs of a decoder whose outputs are arranged in accordance with the function zones of a telecommuni cations system and are connected to inputs of logic-linking elements via whose output signals can be provided to provide statements concerned the operating states of the function zones.

14. Apparatus as claimed in Claim 13 wherein the logic-linking elements each possess at least one input via which it is possible to supply command signals with the aid of which different reactions of the logic-linking elements can be triggered.

15. Apparatus as claimed in Claim 13 or Claim 14 wherein threshold value elements are connected to outputs of the decoder, can be made to adopt any one of a multiplicity of threshold values and serve to recognise respective different minimum numbers of fault indications.

16. Apparatus for locating faults in an electrical system comprising a central device to which is connected a plurality of peripheral units, said apparatus being substantially as described herein with reference to the accompanying drawings.

17. A telecommunication system comprising a central device to which is connected a plurality of peripheral units and including apparatus according to any one of Claims 11 to 16.

18. A system according to Claim 17 wherein the fault localisation or rectification process is arranged to be initiated in the function zone or zones determined as most probable to be faulty.