Fault indicator

About: Fault indicator is a research topic. Over the lifetime, 10057 publications have been published within this topic receiving 143482 citations. The topic is also known as: FCI & power line fault indicator.

On-line hazard aversion and fault diagnosis in chemical processes: the digraph+fault-tree method

Abstract: A method for online hazard aversion and fault diagnosis in chemical processes is developed. The method uses a directed graph model of process operation and control. Fault trees developed from the directed graphs are combined with real-time data to provide online diagnosis for hazard aversion and fault detection. Both hardwired control and manual control are modeled. A single control loop illustrates the modeling technique and the diagnosis method. The method provides an advance alert to process problems and an identification of the problems' causes, based on the available real-time data and prior rates of equipment malfunctions and process disturbances. >

An image forming apparatus provided with self-diagnosis system

Abstract: In an image forming machine, an objective model storage device stores parameter data that represent elements of the machine and relationships among such parameters, and parameter membership functions, and fault diagnosis knowledge A degradation storage device stores a fuzzy qualitative value for a parameter changed by degradation of an element of the machine Preferably, degradation indicative data are converted into fuzzy qualitative values, and the value of the parameter changed by degradation is represented by a fuzzy qualitative value The machine includes sensors for sensing functional states thereof, and providing state data representative of such states The state data sensed by the sensors are converted into fuzzy qualitative values Then, a fault judgement device determines whether or not a fault exists by comparing the obtained fuzzy qualitative values with the parameter data stored in the objective model storage device If the fault judgement device determines that a fault exists, a fault diagnosis device performs fault diagnosis by utilizing, as an initial value, the value of the parameter changed by degradation A specification device specifies fault causes by comparing the result of the diagnosis with the state data which was converted into the fuzzy qualitative values Then, a repair device operates actuators of the machine to overcome the specified fault

A Universal Fault Location Technique for N-Terminal $({N}\geqq 3)$ Transmission Lines

Abstract: This paper presents a universal fault location technique for N-terminal transmission lines based on synchronized phasor measurement units. The development of the technique is based on two-terminal fault location technique. The proposed algorithm is different from traditional multiterminal fault location techniques. We apply two-terminal fault location technique to N-terminal transmission lines and propose a novel fault section selector/fault locator. The proposed method has a very good tolerance. The proposed approach provides an analytical solution and its computational burden is very low since it does not require iterative operations. An extensive series of simulations were conducted to verify the accuracy of the proposed algorithm. The average fault location error under various fault conditions is well below 1%.

Detection of Stator Faults in Induction Machines Using Residual Saturation Harmonics

Abstract: Stator fault is one of the most commonly occurring faults in ac machines. Recent estimates suggest that 30%-40% of all reported induction machine faults are stator fault related. Going by the number of occurrences, the position of stator faults is only second to bearing-related faults. Third harmonic line currents, which are caused by the interaction of a reverse-rotating field and saturation-related permeance variation, the third harmonic component in the line voltage, and the speed ripple consequent to the reverse-rotating field, have been reported to increase under stator fault conditions. Since the reverse-rotating field is produced by voltage unbalance as well as stator faults, the measurement of third harmonic in the line current may not be a reliable estimator of stator faults, particularly at an incipient stage. The third and the other triplen-related harmonics are however found to be a very decisive indicator of the fault if measured in the machine terminal voltages just after switch-off. The fault-detection technique is independent of machine parameters and supply unbalances. Simulation and experimental results with very few shorted turns show that not only the presence of stator fault but also the phase in which the fault has occurred can be detected reliably. However, because of the nature of detection, it should strictly be called an offline method that can only validate existing online schemes, unless used for motors operating continuously in transient modes or form-wound machines