EPE Association: EPE 1995 - 03 - Lecture Session L1c: DRIVES, RELIABILITY ASPECTS

EPE 1995 - 03 - Lecture Session L1c: DRIVES, RELIABILITY ASPECTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 03 - Lecture Session L1c: DRIVES, RELIABILITY ASPECTS

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   DETECTION OF INDUCTION MACHINE INCIPIENT FAILURES USING KNOWLEDGE BASED TECHNIQUES
By M. F. Cabanas; J. G. Aleixandre; M. A. Sanz; A. Neira; A. Otero; J. S. Sariego [View]
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Abstract: This paper describes an expert system for the on-line diagnosis of working cage induction motors. The expert system uses spectral analysis of stator currents and motor vibrations as well as the supply voltages and currents, as input variables. The main difference between the system proposed here and a classical diagnosis expert system is the existence of models; the behaviour of the motor and its parts are defined by a hierarchical object network which incorporates a set of models where both theoretIcal data and data acquired through experience are integrated. The properties of network objects are defined once the motor-drive system has been specified. The structure is therefore dynamically updated for each particular case. Once the system has stored both values of electrical variables and the spectral analysis of currents and vibrations, the informatIon is compared with the data generated by the models, and the inference process subsequently begins when a considerable difference between them is found. The system output consists of the identified failures, evidence found during the diagnosis process, and a maintenance plan based on the knowledge acquired from expert technicians.

   A SURVEY OF THE RELIABILITY WITH AN ANALYSIS OF FAULTS ON VARIABLE FREQUENCY DRIVES IN INDUSTRY
By O. V. Thorsen; M. Dalva [View]
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Abstract: This paper presents an overview of applications and a distribution of variable frequency drives (VFDs) on different load types in industrial and other processes. A survey of the reliability of VFDs has been performed, as well as a closer analysis of registered faults for different industrial applications, environment and converter design. Faults in the VFDs are compared with previous surveys for conventional AC drives. The present survey has been performed on inverters of more generations, and the results will have importance for the choice of system solutions and planning of monitoring and maintenance. The survey is based on collected data from service experience with 666 inverter units within varies types of industrial plants. 522 failures on these have been registered and analyzed. In addition some few motor failures have been registered. The results show that more than 50 % of all failures are in the control circuits, 7.7 % in the cooling fans and 37.9 % in the power circuits. For units below 50 kW the failure rate is about the same for VFDs as for conventional drives, but the failures are now registered for the converter rather than for the motor. For units above 50 kW the failure rate for VFDs are considerably higher than for that of the conventional drives, with a distinct maximum in the power range of 51-100 kW. The survey also shows that for higher power rates the failure rate for VFDs will decrease down to that of the conventional drives. The survey also indicates that the introduction of VFD has decreased the failure rate for the motor.

EPE 1995 - 03 - Lecture Session L1c: DRIVES, RELIABILITY ASPECTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 03 - Lecture Session L1c: DRIVES, RELIABILITY ASPECTS
	[return to parent folder]

	DETECTION OF INDUCTION MACHINE INCIPIENT FAILURES USING KNOWLEDGE BASED TECHNIQUES By M. F. Cabanas; J. G. Aleixandre; M. A. Sanz; A. Neira; A. Otero; J. S. Sariego	[View] [Download]
Abstract: This paper describes an expert system for the on-line diagnosis of working cage induction motors. The expert system uses spectral analysis of stator currents and motor vibrations as well as the supply voltages and currents, as input variables. The main difference between the system proposed here and a classical diagnosis expert system is the existence of models; the behaviour of the motor and its parts are defined by a hierarchical object network which incorporates a set of models where both theoretIcal data and data acquired through experience are integrated. The properties of network objects are defined once the motor-drive system has been specified. The structure is therefore dynamically updated for each particular case. Once the system has stored both values of electrical variables and the spectral analysis of currents and vibrations, the informatIon is compared with the data generated by the models, and the inference process subsequently begins when a considerable difference between them is found. The system output consists of the identified failures, evidence found during the diagnosis process, and a maintenance plan based on the knowledge acquired from expert technicians.

	A SURVEY OF THE RELIABILITY WITH AN ANALYSIS OF FAULTS ON VARIABLE FREQUENCY DRIVES IN INDUSTRY By O. V. Thorsen; M. Dalva	[View] [Download]
Abstract: This paper presents an overview of applications and a distribution of variable frequency drives (VFDs) on different load types in industrial and other processes. A survey of the reliability of VFDs has been performed, as well as a closer analysis of registered faults for different industrial applications, environment and converter design. Faults in the VFDs are compared with previous surveys for conventional AC drives. The present survey has been performed on inverters of more generations, and the results will have importance for the choice of system solutions and planning of monitoring and maintenance. The survey is based on collected data from service experience with 666 inverter units within varies types of industrial plants. 522 failures on these have been registered and analyzed. In addition some few motor failures have been registered. The results show that more than 50 % of all failures are in the control circuits, 7.7 % in the cooling fans and 37.9 % in the power circuits. For units below 50 kW the failure rate is about the same for VFDs as for conventional drives, but the failures are now registered for the converter rather than for the motor. For units above 50 kW the failure rate for VFDs are considerably higher than for that of the conventional drives, with a distinct maximum in the power range of 51-100 kW. The survey also shows that for higher power rates the failure rate for VFDs will decrease down to that of the conventional drives. The survey also indicates that the introduction of VFD has decreased the failure rate for the motor.