Abstract
The search for more competitive equipment in the global market has led to the implementation of new materials and technologies in the search for greater energy efficiency. This is certainly a guideline followed by the electric motor industry that has introduced new technologies in rotating machines, such as the permanent magnet motor, evolving into increasingly efficient motor classes. However, subjecting these efficient motors under nonideal electric grid power conditions, such as voltage unbalance, can cause these efficient machines to generate additional distortions in the voltage and current waveforms, which in turn not only affect the performance of electric motors themselves but also that of the electrical system in general. This work presents a comparison between energy efficiency gain and the corresponding power quality degradation through a detailed harmonic analysis of the effects of voltage harmonics and voltage unbalance in three 0.75-kW electric motors classes: IE2, IE3, and IE4, The results show that for increasing percentages of a specific harmonic distortion, other harmonics are also increased in the higher efficiency electric motors sample analyzed, and similar responses were also observed for large percentages of voltage unbalance, mainly in the line-start permanent magnet motor class IE4. The results achieved are interesting but rigorously reflect only the tested motor sample and cannot be generalized to all motors, in other power ranges, of the respective motor classes tested. For generalization, exhaustive tests must be accomplished to formulate general conclusions according to the electric motors’ classes commercially available.
Highlights
Over the years, the interest in implementing energy efficiency actions has been adopted by many countries, in search of a green and sustainable future
The results revealed that, for the motors sample analyzed in this work, the more efficient motors are more sensitive to disturbances in the electrical systems, behaving as sources of amplification of existing harmonics in the presence of these disturbances, with which the doubt arises: Are the most efficient motors less efficient in power quality terms?
It can be seen how at an economic point of view the implementation of more efficient electric motors results in greater long-term savings, regardless of their initial cost. This is undoubtedly the main motivation for replacing less efficient motors by more efficient ones. Their impacts on a large scale, including issues related to power quality regulation, must be analyzed to verify if the industrial installation complies with current legislation with respect to energy quality indicators, such as total harmonic distortions of current and voltage at the point of common coupling with the electrical network
Summary
The interest in implementing energy efficiency actions has been adopted by many countries, in search of a green and sustainable future. Given the greater efficiencies in electric motors, as a result of the implementation of new technologies, studies comparing different efficiency classes have been presented in [14]–[18], the economical, technical and ecological benefits as well as the main operational challenges are discussed in these works. The introduction of new technologies translates into lower consumption and greater savings, making the substitution between technologies attractive Given this scenario, studies on the performance of new technologies such as the line-start permanent magnet motor must be carried out to evaluate the advantages and points to consider in large-scale uses. Studies on the performance of new technologies such as the line-start permanent magnet motor must be carried out to evaluate the advantages and points to consider in large-scale uses In this sense, this work presents a comparison between energy efficiency gain and power quality degradation related to electric motors. The results revealed that, for the motors sample analyzed in this work, the more efficient motors are more sensitive to disturbances in the electrical systems, behaving as sources of amplification of existing harmonics in the presence of these disturbances, with which the doubt arises: Are the most efficient motors less efficient in power quality terms?
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