| In this thesis, work has been done trying to provide advances in: (1) Knowledge of the modifications in the behavior of induction motor when any of their more significant faults appears. (2) Early and reliable diagnosis of failures.;To be able to understand and examine the engines behaviour with regard to these anomalies, a dynamic model, based on mutually connected circuits is developed, in which the most important faults in this kind of machines can be implemented, in their different aspects and severities. In this way, modifications which appear in the main functional parameters for different types of failure, degrees of breakdown, construction features, operational rates or external agents (vibrations, variations in load, etc.) can be studied.;Validity of the theoretical schemes developed in the model is verified by means of the comparison of the results obtained from the simulation with those obtained from experimental tests with a two speeds engine of induction. The tests which have been done try to cover all the possibilities of functioning. This way, tests are carried out for the diverse types of fault, different degrees of severity for each of them, for the two possible configurations of the engine, with a varied spectrum of resistant loads, and both in permanent and transitory take-off rates. The tests reveal for all the cases a very similar behaviour in the results of the simulations and in the measures taken in the real engine, for similar test configurations.;On the other hand, five techniques of electromechanical check for the diagnosis of the condition of electrical asynchronous engines are developed. For each technique, indicators related to the severity of the faults studied are proposed. The values of these coefficients allow to differentiate between each one of the anomalies, as well as to follow up each one of them.;The main failures which may occur in engines of induction (eccentricity, faults in bearings, squirrel cage asymmetry, stator inter-turn) are studied, analysing the main causes which produce the failure, its evolution and possible consequences, and the current techniques used for its detection and diagnosis.;Tests are carried out in order to verify the efficiency of each one of the methods developed, not only in a simulated way, but also by means of real tests, from which behaviours of the indicators for different functional conditions are obtained. Simultaneously, other usual techniques, which are used nowadays for breakdown diagnosis in these engines, are applied. Finally, the results obtained with one and other techniques of verification are checked.;The first of these methods is based on the measurement of the instantaneous power transmitted by the engine. According to the results obtained by means of simulation and experiments, the indicators proposed in this technique present good services for the diagnosis of the faults of eccentricity, squirrel cage asymmetry and stator inter-turn. This technique is insensitive to the punctual injuries of the bearings, at least with the degree of severity with which the tests have been carried out.;The other four techniques are based on the treatment and analysis of the fundamental component of the magnetomotive force of the air-gap (TMF), in a exclusive way or together with instantaneous angular speed. These methods are: the frequency spectrum of the TMF, the relationship between the extent and the draft speed of the TMF, the orbital of the TMF and the instantaneous slide between the TMF and the rotor. From the results obtained of the application of these techniques it is deduced that, with their utilization, it is possible to detect and diagnose the main faults of induction engines in their initial stadiums and with a high reliability.;Finally, as a part of the tools developed to achieve the set goals, a new system for the measurement of the instantaneous angular speed has been developed. This system is based on the calculation of the time passed between flanks of the same sign as that of the signal coming from an incremental encoder. (Abstract shortened by UMI.)... |
