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Showing papers on "Fault indicator published in 1994"


Journal ArticleDOI
TL;DR: The authors propose a new alarm structure, propose a general model for representing the network, and give two algorithms which can solve the alarm correlation and fault identification problem in the presence of multiple faults.
Abstract: Presents an approach for modeling and solving the problem of fault identification and alarm correlation in large communication networks. A single fault in a large network may result in a large number of alarms, and it is often very difficult to isolate the true cause of the fault. This appears to be one of the most important difficulties in managing faults in today's networks. The problem may become worse in the case of multiple faults. The authors present a general methodology for solving the alarm correlation and fault identification problem. They propose a new alarm structure, propose a general model for representing the network, and give two algorithms which can solve the alarm correlation and fault identification problem in the presence of multiple faults. These algorithms differ in the degree of accuracy achieved in identifying the fault, and in the degree of complexity required for implementation. >

222 citations


Journal ArticleDOI
TL;DR: The approach presented involves injecting transient faults into integrated circuits by using heavy-ion radiation from a Californium-252 source to inject faults at internal locations in VLSI circuits.
Abstract: Fault injection is an effective method for studying the effects of faults in computer systems and for validating fault-handling mechanisms. The approach presented involves injecting transient faults into integrated circuits by using heavy-ion radiation from a Californium-252 source. The proliferation of safety-critical and fault-tolerant systems using VLSI technology makes such attempts to inject faults at internal locations in VLSI circuits increasingly important. >

188 citations


Journal ArticleDOI
TL;DR: A new fault location system for multi-terminal single transmission lines and an algorithm for synchronizing the asynchronous sampling data is presented and EMTP simulation results are presented.
Abstract: Conventional fault location systems which use one-terminal AC voltages and currents are difficult to apply to multi-terminal power systems. This paper discusses a new fault location system for multi-terminal single transmission lines. Asynchronous sampling at each terminal is preferred in order to simplify the transmission equipment and an algorithm for synchronizing the asynchronous sampling data is presented. Another algorithm is presented which converts the original multi-terminal power system by progressive conversion to a system with one fewer terminals to arrive at a 2-terminal system containing the fault. An effective fault locating system can be constructed by combining these algorithms with existing reactive power locating operations. EMTP simulation results are presented. >

101 citations


Journal ArticleDOI
TL;DR: This paper presents an extension of the well-known Beard-Jones detection filter that permits isolation of sensor faults in a dynamic system to a fixed direction in output space and converts the sensor fault into the same form as an actuator fault.

96 citations


Patent
18 Nov 1994
TL;DR: In this paper, the authors proposed a method to locate the location of a fault in an energized power distribution cable by moving the antenna along the line until the polarity of the initial received pulse inverts, in order to determine the precise location of the fault.
Abstract: When a fault in an energized power distribution cable flashes over, the surge draws charge from both sides of the line. The fault thus produces a pair of current surges that propagate from the fault in opposite directions along the line. These oppositely-directed current surges create pulsed electromagnetic fields of different directions which, in turn, induce voltages of different polarities in a receiving antenna positioned along the line. The polarity of the first such voltage pulse induced in the antenna indicates the direction from the antenna to the fault. In one embodiment, the line is repeatedly "thumped," causing flashovers to recur at the fault. By moving the antenna along the line until the polarity of the initial received pulse inverts, the precise location of the fault can be determined. In another embodiment, direction-indicating fault current indicators according to the present invention are permanently placed at numerous locations in an operating AC power distribution system, in anticipation of a fault. When a fault occurs, the polarity of the first received electromagnetic fault pulse at each device indicates the respective direction from the device to the fault.

96 citations


Journal ArticleDOI
TL;DR: This framework provides a basis for understanding transient fault problems in digital systems and can be helpful in selecting optimum techniques to mask or eliminate transient fault effects in developed systems.
Abstract: It is hard to shield systems effectively from transient faults (fault avoidance techniques). So some other means must be employed to assure appropriate levels of transient fault tolerance (insensitivity to transient faults). They are based on fault-masking and fault recovery ideas. Having analyzed this problem, the author identifies critical design points and outlines some practical solutions that refer to efficient on-line detectors (detecting errors during the system operation) and error handling procedures. This framework provides a basis for understanding transient fault problems in digital systems. It can be helpful in selecting optimum techniques to mask or eliminate transient fault effects in developed systems. >

94 citations


Journal ArticleDOI
TL;DR: In this paper, a logic level characterization and fault model for crosstalk faults is presented, and a fault list of such faults can be generated from the layout data, and given an automatic test pattern generation procedure for them.
Abstract: The continuous reduction of the device size in integrated circuits and the increase in the switching rate cause parasitic capacitances between conducting layers to become dominant and cause logic errors in the circuits. Therefore, capacitive couplings can be considered as potential logic faults. Classical fault models do not cover this class of faults. This paper presents a logic level characterization and fault model for crosstalk faults. The authors also show how a fault list of such faults can be generated from the layout data, and give an automatic test pattern generation procedure for them. >

94 citations


Proceedings ArticleDOI
06 Nov 1994
TL;DR: Using the technique presented here an efficient static test set for analog and mixed-signal ICs can be constructed, reducing both the test time and the packaging cost.
Abstract: Static tests are key in reducing the current high cost of testing analog and mixed-signal ICs. A new DC test generation technique for detecting catastrophic failures in this class of circuits is presented. To include the effect of tolerance of parameters during testing, the test generation problem is formulated as a minimax optimization problem, and solved iteratively as successive linear programming problems. An analytical fault modeling technique, based on manufacturing defect statistics is used to derive the fault list for the test generation. Using the technique presented here an efficient static test set for analog and mixed-signal ICs can be constructed, reducing both the test time and the packaging cost.

86 citations


Patent
09 Feb 1994
TL;DR: In this paper, a fault detecting system for a computer network comprising a plurality of computer systems which are placed apart and interconnected by a communication network, and a central computer system monitors faults in the network.
Abstract: The present invention is for a fault detecting system for a computer network comprising a plurality of computer systems which are placed apart and interconnected by a communication network, and a central computer system monitors faults in the network. The central computer system stores fault information which is transmitted from a plurality of computer systems and judges whether the information indicates a fault occurring for a slight fault or for a serious fault based on the length of the duration of the fault, and display means performs the alarm display for a case of a serious fault and does not display for a case of a slight fault. As a result, the central computer system effectively detects faults in a computer network in which a plurality of computer systems are interconnected with the central computer system by means of a monitoring system that automatically distinguishes serious faults from slight faults.

85 citations


Patent
27 Jun 1994
TL;DR: In this paper, a fault diagnosis apparatus for a vehicle control system is presented. But the fault diagnosis is useful in diagnosing a fault of an electronic component mounted on a vehicle, especially when the fault has led to such a control as deteriorating exhaust gas.
Abstract: This invention relates to a fault diagnosis apparatus for a vehicle control system. The fault diagnosis apparatus is useful in diagnosing a fault of an electronic component mounted on a vehicle, especially when the fault has led to such a control as deteriorating exhaust gas. It is an object of this invention to minimize an increase in the manufacturing cost upon incorporation of such a fault diagnosis apparatus. According to this invention, the vehicle control system has an automatic transmission operation state detection sensor, an engine operation state detection sensor, an automatic transmission control unit and an engine control unit. For the diagnosis of a fault of at least one of the sensors and control units, the fault diagnosis apparatus comprises a fault determining unit, a code converter, a fault determining unit, a code converter, an ISO converter and a determining and diagnosing tester.

81 citations


Proceedings ArticleDOI
06 Nov 1994
TL;DR: Time-domain testing followed by spectral analysis of the power-supply current is used to detect both DC and AC faults and a probabilistic decision rule is proposed based on a multivariate statistical analysis for fault detection.
Abstract: A new method for the testing and fault detection of analog integrated circuits is presented. Time-domain testing followed by spectral analysis of the power-supply current is used to detect both DC and AC faults. Spectral analysis is applied since the tolerances on the circuit parameters make a direct comparison of waveforms impossible. For the fault detection a probabilistic decision rule is proposed based on a multivariate statistical analysis. Since no extra testing pin is needed and the on-line calculation effort is small, the method can be used for wafer-probe testing as well as final production testing. In addition, a methodology for the selection of the input stimulus is presented that improves the test-ability. Examples demonstrate the efficiency and the effectiveness of the algorithms.

Journal ArticleDOI
TL;DR: In this paper, a new algorithm is proposed based on symmetrical components theory, which has computational advantage over previously suggested symmetrical component-based algorithms, and a procedure for applying shunt fault conditions to the sequence equations to estimate fault impedance of the protected transmission line is discussed.
Abstract: Fault impedance is one of the major parameters that must be estimated accurately in digital distance relaying application. In this paper, a new algorithm is proposed based on symmetrical components theory. The proposed algorithm has computational advantage over previously suggested symmetrical components based algorithms. A procedure for applying shunt fault conditions to the sequence equations to estimate fault impedance of the protected transmission line is discussed. The Alternative Transient Program (ATP) that is available on personal computers was used in evaluating the proposed algorithm. ATP models a power system and simulates many fault conditions on a selected transmission line. Fault data obtained were used in calculating fault impedance using the proposed algorithm. Fault impedance estimates were inserted in relay characteristics to determine suitability of the proposed algorithm for first zone distance protection. Sample results of these studies which show stable fault distance estimates are presented and discussed in the paper. >


Proceedings ArticleDOI
12 Jun 1994
TL;DR: DEFINE can inject both hardware faults and software faults into any process running in a distributed system, either in user mode or in supervisor mode, and monitor the fault impact and propagation in software systems and among machines.
Abstract: This paper presents a distributed fault injection and monitoring environment (DEFINE) as a tool to evaluate system dependability, to investigate fault propagation, and to validate fault-tolerant mechanisms. DEFINE can inject both hardware faults (hardware-induced software errors) and software faults into any process running in a distributed system, either in user mode or in supervisor mode, and monitor the fault impact and propagation in software systems and among machines. It employs two fault injection techniques: (i) using hardware clock interrupts to control the time of fault injection and activation, and (ii) using software traps to inject all the faults except communication faults and memory faults in the data/stack segment. Experiments on six Sun SPARCstations to study the system behavior under faults are conducted to demonstrate the application of DEFINE.

Patent
03 Feb 1994
TL;DR: In this paper, a plug-in ground fault monitor module for a circuit breaker trip unit is presented, which stores data representative of the particular function of the trip unit and enables it to adapt to communicate monitored ground fault data to the ground fault module.
Abstract: The present invention provides a plug-in ground fault monitor module for a circuit breaker trip unit configured to operate with a plurality of different plug-in plug-in modules. The ground fault monitor module includes a memory which stores data representative of the its particular function. This memory is readable by the trip unit and enables the trip unit to automatically adapt to communicate monitored ground fault data to the ground fault module. The ground fault module also includes means for setting threshold levels for a ground fault alarm signal. The ground fault alarm signal is generated independently of ground fault alarms in the trip unit based on its internal thresholds. This signal can be used to control an external relay which operates a shunt trip mechanism or an external alarm. The trip unit includes a processor and programming which permits a bi-directional flow of data between the units, such as display data and control data.

Patent
19 May 1994
TL;DR: A fault tolerant automotive serial communication network includes a central communication node directly connected to a plurality of automotive electronic devices through corresponding interface circuitry including fault tolerant circuitry for detecting a serial communication fault in the corresponding device and for rapidly and substantially unintrusively removing the device from the network for the duration of the detected fault to minimize the impact of the fault on network operation as mentioned in this paper.
Abstract: A fault tolerant automotive serial communication network includes a central communication node directly connected to a plurality of automotive electronic devices through corresponding interface circuitry including fault tolerant circuitry for detecting a serial communication fault in the corresponding device and for rapidly and substantially unintrusively removing the device from the network for the duration of the detected fault to minimize the impact of the fault on network operation.

Proceedings ArticleDOI
15 Jun 1994
TL;DR: A microprocessor error behavior function (EBF) is introduced, mapping faults into errors on the functional level, and the results of the emulated bit-flip errors corresponded well to the real results obtained using bit-Flip faults, thus indicating that the injected errors are good approximations of the faults.
Abstract: A microprocessor error behavior function (EBF) is introduced, mapping faults into errors on the functional level. The errors are obtained using a functional model of the processor. By applying the EBF to a fault and instruction distribution, it is possible to obtain the corresponding error distribution. A case study is described, in which (i) the EBFs for simulated bit-flip and pin-level faults are designed and used to compare the bit-flip and pin-level fault models, and (ii) the obtained error distribution for the bit-flip faults is used in an error injection experiment on the functional level to emulate these faults. For the processor used in the case study, it was found that only 9-12% of the bit-flip faults could be emulated using pin-level faults, while a tentative evaluation of the possibility to emulate bit-flip faults with software-implemented fault injection showed that 98-99% could be emulated. Finally, the results of the emulated bit-flip errors corresponded well to the real results obtained using bit-flip faults, thus indicating that the injected errors are good approximations of the faults. >

Patent
09 May 1994
TL;DR: In this article, the authors propose a power system fault handling mechanism for portable electronic devices having multiple power supplies, which couples all available power supplies to the power load, yet avoids feeding power back from any of the supplies to one another.
Abstract: A power system fault handling mechanism for portable electronic devices having multiple power supplies. A safety-net circuit is triggered when a power fault condition is detected. The safety-net circuit is a diode-based bridging circuit which couples all available power supplies to the power load, yet avoids feeding power back from any of the supplies to one another. This ensures that the load continues to receive power after a fault condition occurs without interruption. A microcontroller may then implement routines to switch to a working power supply so that the device may resume normal operation. The power system fault detection mechanism thus allows for the switching between system power supplies without disrupting a running process.

Patent
Brion L. Keller1
09 Jun 1994
TL;DR: In this article, a method and system for defining and using a pattern fault file having a static pattern fault and/or a dynamic pattern fault is presented, where the fault propagation point is defined to be a net or node in a circuit to be tested where the defect's effect first appears once it has been excited.
Abstract: A method and system (12) for defining and using a pattern fault file (15) having a static pattern fault and/or a dynamic pattern fault A static pattern fault is represented as a list of required excitation nodes and their values, as well as a fault propagation point The fault propagation point is defined to be a net or node in a circuit to be tested where the defect's effect first appears once it has been excited A dynamic pattern fault adds to this structure an initial value list of nodes and their required initial values The dynamic-pattern fault is employed to advantage when a two pattern sequence is required to excite a specific defect Logical combinations (AND/OR) of specified pin excitations and fault propagation points may be employed The excitation value list, the initial value list and the propagation point can include any of the following: input pins of an entity; output pins of the entity; nets inside of the entity; pins on usage blocks inside the entity; nets inside a usage of a lower entity; and pins inside a usage of a lower level entity The method and system also provide a capability to define pattern faults for each entity in a hierarchial circuit definition, and thus provides a mechanism to define pattern faults for specific cells in a cell technical library (13)

Journal ArticleDOI
TL;DR: In this article, the authors re-examined the fault detectability and isolability of the residual signal of an inverted pendulum system with possible sensor, actuator and component faults.

Journal ArticleDOI
TL;DR: In this article, a fault detection and diagnosis (FDD) system for the Space Shuttle main engine is presented, which utilizes a model-based method with real-time identification and hypothesis testing for actuation, sensor, and performance degradation faults.
Abstract: The paper presents the development of a fault detection and diagnosis (FDD) system with applications to the Space Shuttle main engine. The FDD utilizes a model-based method with real-time identification and hypothesis testing for actuation, sensor, and performance degradation faults.

Patent
31 Oct 1994
TL;DR: In this article, the authors present a method and system which determine signal probability and transfer probability for each node in a netlist describing an electrical circuit; determine, using the signal probabilities and transfer probabilities, a fault detection probability; and, using fault detection probabilities, determine overall fault coverage of the electrical circuit described in the netlist.
Abstract: The present invention is a method and system which determine signal probability and transfer probability for each node in a netlist describing an electrical circuit; determine, using the signal probability and transfer probability, a fault detection probability for each node; and, using the fault detection probabilities, determine overall fault coverage of the electrical circuit described in the netlist. The method and system of the present invention then, using the fault coverage data, heuristically determine a set of testpoints to be inserted into the netlist which increase the overall fault coverage of the electrical circuit above a predetermined value.

Patent
Anthony R. Bonaccio1
31 May 1994
TL;DR: An improved cable fault detection system which makes the fault detection independent of the ground shift between units coupled to the interface is presented in this paper.This fault detection is based on differentially sensing the voltage on a wire pair, in a cable, and using the differential voltage applied to the wires to make a decision as to whether or not the cable is faulted.
Abstract: An improved cable fault detection system which makes the fault detection independent of the ground shift between units coupled to the interface This fault detection is based on differentially sensing the voltage on a wire pair, in a cable, and using the differential voltage applied to the wires to make a decision as to whether or not the cable is faulted The disclosed differential sensing and fault checking scheme reviews both data states thus making the fault detection independent of the ground shift between machines on the interface and this is accomplished without reducing the load impedance presented to the cable by the differential receiver coupled thereto

Journal ArticleDOI
TL;DR: In this article, a new concept for fault location has been developed which uses fault-generated waves to perform both real-time and after-the-fact fault location on single-phase underground residential distribution cable systems that are up to a mile in length.
Abstract: A new concept for fault location has been developed which uses fault-generated waves to perform both real-time and after-the-fact fault location on single-phase underground residential distribution cable systems that are up to a mile in length. In either mode, faults are located with an accuracy of less than 2 percent of the length of the cable circuit. Thus, a fault can easily be located as being between two adjacent transformers. A device based on the concept would be installed at the normally open point of a radial URD tap, and would monitor the circuit for fault-created transients. When triggered by either a real-time fault transient or an after-the-fact thumper impulse, the conceptual device would provide a digital readout of the distance to the fault, allowing for rapid isolation of the faulted section of cable. >

Proceedings ArticleDOI
25 Apr 1994
TL;DR: The authors demonstrate that as defect level decreases the uncertainty of the estimate grows and the limitations of using the stuck-at fault coverage to predict the defect level are shown.
Abstract: The stuck-at fault model has been used over decades as a guide to the test generation process and as an evaluation mechanism for the quality of the test set. As demands on quality have increased, the use of the stuck-at fault model as a predictor of the defect level has been questioned. This paper provides some insight on the issue and shows the limitations of using the stuck-at fault coverage to predict the defect level. The authors demonstrate that as defect level decreases the uncertainty of the estimate grows. >

Proceedings ArticleDOI
26 Jun 1994
TL;DR: A novel hybrid fuzzy/neural fault detector that uses the learning capabilities of the neural net to detect if a motor has an incipient fault, and gives the heuristic reasoning for the fault detection procedure.
Abstract: Neural net have proven to be capable of solving the motor monitoring and fault detection problem using an inexpensive, reliable and noninvasive procedure. The neural net, unfortunately, cannot provide heuristic knowledge about the motor or the fault detection process. This paper introduces a novel hybrid fuzzy/neural fault detector that uses the learning capabilities of the neural net to detect if a motor has an incipient fault. Once the fuzzy/neural fault detector is trained, heuristic knowledge about the motor and the fault detection process can also be extracted. With better understanding of the heuristics through the use of fuzzy rules and fuzzy membership functions, we can have a better understanding of the fault detection process of the system; thus we can design better motor protection systems. The electric motors in industry are exposed to a wide variety of environments and conditions. These factors, coupled with the natural aging process of any machine, make the motor subject to incipient faults. These incipient faults, left undetected, contribute to the degradation and eventual failure of the motors. With proper monitoring and fault detection schemes, the incipient faults can be detected; thus maintenance and down-time expenses can be reduced while also improving safety. In this paper, motor bearing faults in single-phase induction motors are used to illustrate this novel system. This illustration demonstrates the successful training of a hybrid fuzzy/neural system that can provide accurate fault detection, and gives the heuristic reasoning for the fault detection procedure. >

Patent
31 Mar 1994
TL;DR: In this paper, an apparatus for measuring efficiency losses in a pump is presented, which includes a temperature sensor located at the pump input, a second temperature sensor at a second location, a fluid flow sensor at the second location and a processor for producing a difference signal in response to signals from the first and second temperature sensors and for quantifying efficiency losses of the pump.
Abstract: An apparatus for indicating efficiency losses in a pump is provided. The apparatus includes a temperature sensor located at the pump input, a second temperature sensor located at a second location, a fluid flow sensor located at the second location, a processor for producing a difference signal in response to signals from the first and second temperature sensors and for quantifying efficiency losses of the pump in response to the difference signal and a signal from the fluid flow sensor. A fault indicator is also provided that is responsive to the efficiency losses.

Proceedings ArticleDOI
25 Oct 1994
TL;DR: A number of results pertaining to the possibly-faulty sensors pointed out by the algorithm are derived which help narrow down the search to detect faulty sensors and to bound the number of intervals needed to construct an accurate and reliable "abstract sensor".
Abstract: Replicating sensors is desirable not only to tolerate sensor failures but also to increase the expected accuracy of the ensemble of replicated sensors beyond that obtainable with a single one. Such replication is used in a multisensor environment or in a distributed sensor network. We model a continuous valued sensor as an interval of real numbers containing the physical value of interest. Given n sensors of which at most f of them can suffer arbitrary failures, we present an efficient O(n log n) fault tolerant algorithm whose output is reliable when f >

Proceedings ArticleDOI
21 Mar 1994
TL;DR: In this article, a fault detection method for generating robust residuals for a bilinear system with unknown inputs is proposed, and necessary and sufficient conditions for the existence of a fault detector are given.
Abstract: A fault detection method is proposed for generating robust residuals for a bilinear system with unknown inputs. Necessary and sufficient conditions for the existence of a fault detection observer are given. The method is applied to a hydraulic system and simulation results are given.< >

Patent
12 Aug 1994
TL;DR: In this article, a composite asynchronous/synchronous system switches signal paths at the time of a fault and uses a route diversity function even when a fault occurs in the asynchronous mode signal.
Abstract: A composite asynchronous/synchronous system switches signal paths at the time of a fault and uses a route diversity function even when a fault occurs in the asynchronous mode signal. The composite system includes asynchronous system fault notifying means (31) in each of the connection offices (13A) connecting the synchronous communication system and the asynchronous communication system. When an asynchronous system alarm indication signal AIS shows suspension of the asynchronous mode signal or a fault in the signal, the notifying means converts a fault detection signal to information recognizable in the synchronous mode and sends the information to an asynchronous system fault path switching means (32) which is provided in the path termination office (13B). The switching means detects the fault detection signal generated in the asynchronous mode, or receives the fault detection signal sent from the asynchronous system fault notifying means, and switches paths formed on ring-like transmission lines.