Energy Efficiency in Motor Systems

This chapter focuses on the main electric motor technologies to increase the efficiency of variable speed applications such as permanent magnet motor (interior PM, surface PM, hybrid PM), synchronous reluctance motor, line-start PM motor, switched reluctance motor, transverse flux motor, and axial flux motor. In order to understand the advantages of different motor technologies and their feasibility for variable speed application, a comparison between the main characteristics of permanent magnet motors (IPM, SPM, and HSM), synchronous reluctance motors, and induction motors are presented, considering the induction motor as reference.

In response to various opinions about the feasibility of maintaining motor efficiency during repair, including replacement of the stator winding, the Electrical Apparatus Service Association (EASA) and the Association of Electrical and Mechanical Trades (AEMT) conducted two comprehensive rewind studies using third-party testing laboratories. The results of the first study, which were published in 2003 (The Effect of Repair/Rewinding on Motor Efficiency. Electrical Apparatus Service Association, 2003), clearly showed that the efficiency of energy efficient and IE2 motors ranging from 7.5 hp to 200 hp (5.5 kW to 150 kW) can be maintained (and sometimes improved) if the stator is rewound using established good practice procedures. The increasing use of premium efficient motors mandated by various countries led to a second rewind study in 2019, this time to determine if the efficiency of premium efficiency and IE3 motors can be maintained when they are rewound using the good practices described in the 2003 rewind study and ANSI/EASA AR100–2015 (Recommended Practice for the Repair of Rotating Electrical Apparatus. Electrical Apparatus Service Association (EASA), ANSI/EASA AR100, 2015). As with the 2003 study, the results of the 2019 rewind study of premium efficient and IE3 motors ranging from 40 hp to 100 hp (30 kW to 75 kW) clearly indicated that the answer was affirmative—with the average efficiency change for the entire test group falling within the range of accuracy for the test method (± 0.2%). This paper addresses the test methods, methodology, test results, and technical details of the 2019 rewind study.

In three-phase squirrel-cage induction motors (SCIMs) fed by variable-speed drives (VSDs), the no-load harmonic losses associated with the pulse-width modulated (PWM) voltage can have a significant impact on motor efficiency and temperature rise. Moreover, the PWM switching frequency selected in the VSD has a direct impact on SCIM PWM-related harmonic losses, VSD inverter losses, and power drive system (PDS) efficiency. In this chapter, the main results of an experimental assessment of PWM-related losses in a 7.5-kW PDS integrating a commercial VSD and a 4-pole SCIM of IE1, IE2, IE3, and IE4 efficiency classes are presented for 2-, 5-, 16-kHz switching frequency and 25- and 50-Hz fundamental frequency, at no-load and rated-torque operation. Based on experimental data, the coefficients of empirical equations to model VSD losses and SCIM PWM-related losses are found using an evolutionary solving method. These equations can be used to fairly predict the best switching frequency and expected efficiency of VSD, SCIM, and PDS for different operating conditions. Among all motors tested, the IE4-class SCIM showed the highest no-load loss percentage increase due to PWM-related harmonic losses.

The selection of the number of poles of three-phase, squirrel-cage induction motors (SCIMs) for a given set of operating points of a variable-speed power drive system is not straightforward. In this chapter, the performance of 2-pole and 4-pole 50-Hz SCIMs for specific torque-speed operating points and optimized sinusoidal supply voltage in terms of frequency and amplitude is compared by means of simulations and experimental tests. For a given target torque, it is shown that the 4-pole SCIM has lower losses and absorbs less current at a target speed of 1500 r/min and the 2-pole SCIM has lower losses at a target speed of 3000 r/min but absorbs more current. The reduction of the motor current leads to lower conduction losses in the variable-speed drive, contributing to the increase of the power drive system efficiency. The conclusions presented in this paper contribute to a better decision regarding the selection of the number of poles and rated power of SCIMs for a given torque-speed range.

The surveillance of the asynchronous motors market requires laboratories equipped with high-performance instrumentation, according to international regulations and state-of-the-art electrical power measurement devices. Moreover, ad hoc procedures and algorithms for estimating measurement uncertainties are also needed. In this paper, an accurate evaluation of the international standards have been performed, and application software for measuring indirect efficiency with its uncertainty has been presented.

The design of electrical machines used in traction applications trends towards smaller and more efficient motors. Therefore, the thermal design aspect becomes more relevant. Conventional cooling methods may not have sufficient cooling capability and novel cooling concepts, like oil spray cooling of the end windings, are needed. However, no reliable correlations for the prediction of the cooling capability of oil spray cooling methods are available. This paper contributes with a design approach for the pressure difference of a shaft oil spray cooling system, which is essential for the regulation of the pumping system as well as the determination of the outlet pressure. Dimensionless numbers and analytical relationships are used to reduce the parameter space. The impact of the number of radial holes and the rotational speed can be approximated analytically. With the use of the non-dimensional Euler and Hagen number, the results are applicable to every Newtonian fluid at any temperature as long as the fluid properties are known. A sensitivity analysis is performed for the shaft geometries, showing that the diameter of the radial holes and the volumetric inlet flow have a major influence on the pressure difference, whereas the inner and outer diameter of the shaft exhibit a minor influence. The results of the above-mentioned approach are used to establish a series of tests to determine the heat transfer coefficients of liquid impingement jets on a plain surface using orifice-like nozzles at varying input pressures and volumetric inlet flow rates. The measurements showed that a smaller hole diameter of the nozzles and a higher volumetric inlet flow led to a higher heat transfer coefficient. The higher the temperature of the fluid, the higher the heat transfer coefficient. The nozzle distance, on the other hand, has no influence on the heat transfer coefficient and can therefore be neglected in the design process.

Measurements of motor efficiency maps are an important aspect in the determination of motor characteristics. However, standardized efficiency classes are based on the losses of only one load point. An extension to efficiency maps is difficult due to transient effects like temperature drift during measurement. The scale of temperature change depends on aspects like measurement time and transient processes, which can vary between different measurements and thus may cause poor reproducibility. This chapter presents a new method that compensates this behavior without the need of control. By introducing compensation points, the average losses remain constant and therefore the temperature does too. Simulations with a detailed motor model as well as measurements on a test bench confirm this theory and show that measuring high-resolution efficiency maps with hardly any deviation from rated temperature is possible.

A direct calorimetric test bench is presented, designed to test drives, motors and gearboxes with power losses up to 20 kW and a mechanical output power of 150 kW, up to 6000 rpm. The calorimeter setup is a direct type; therefore, it determines the power losses of a device under test (DUT) by measuring the coolant temperatures and flow rate. This type of measurement achieves an uncertainty below 1% on the power loss determination. The construction of the test bench, the required measurement equipment, the measurement procedure and especially measurement uncertainties and results are described in detail. The test case results of a measurement campaign with an electric axle drive, consisting of a liquid-cooled inverter, liquid-cooled high-speed permanent magnet synchronous motor and integrated slip-controlled clutch and gearbox, are presented. The calorimetric setup reaches an uncertainty of ±0.7% or ±25.9 W on the power loss at 25 kW mechanical output power.

The hyperloop technology presents an opportunity for low-energy consumption high-speed transport, thanks to a reduction of air pressure within a tube-guided transport mode. This chapter focuses on the integration of a propulsion system in the tube, regarding its mechanical and electro-magnetic aspects. The structure for connecting the propulsion motor to the surrounding tube is designed for the loads that the machine needs to withstand, at all exploitation speeds up to 1000 km/h. The connection of the stator housing to the tube has a stray field impact linked to the position of the connecting ribs. When the rib is located behind a stator slot, some more flux penetration into the rib is noted, compared to when it is located behind a stator tooth. The impact of the structure on force development and losses in the motor are verified, comparing 2D with 3D Finite Element methods, implemented in JMAG. Regarding the prediction of magnetic flux in the stator and the generated propulsion force, excellent agreement is obtained. The 3D model predicts higher losses than 2D models, due to additional structural components and stray fields at the end of the stator stack. Losses in the structural components are significant but smaller than core losses in the stator yoke, due to the large lamination thickness used. At high speeds, the core losses in stator laminations were calculated using a 3D model of a single lamination, in order to model the skin effect. This results in a higher eddy-current level than the simplified 2D approach suggests.

With the expected surge in electric vehicle (EV) sales over the next 10 years, there is growing concern that EV manufacturing will have a major negative environmental impact and suffer from disruptions in material supply. In particular, using rare-earth metals in the permanent magnets of the most ubiquitous EV motor could become increasingly controversial. Consequently, the European Commission funded the ReFreeDrive research project (grant agreement 770143), aiming to develop next-generation electric drivetrains entirely free of rare earth raw materials. The project developed eight different rare-earth-free motor prototypes based on three major technologies: copper rotor induction motors, synchronous reluctance motors with ferrite permanent magnets, and synchronous reluctance motors without permanent magnets. Through innovations at multiple levels (rotor design, stator using hairpin windings, advanced manufacturing techniques, use of advanced materials) the project demonstrated substantial improvements compared to state-of-the-art examples of these three motor types, achieving a 30% specific torque increase, a 50% reduction in motor losses, and lowering costs by between 15% and 35%. The proposed solutions are all suitable for mass production and eliminate the risks associated with critical rare earth material supply. Through performance optimization, the alternative motors developed as part of the project close the gap to rare-earth permanent magnet motors in terms of power density and total driving efficiency for a given powertrain cost. They also have significantly less negative environmental impact compared to the reference models.

The paper presents a high speed 200 kW synchronous reluctance (SynR) motor for a full electric vehicle. It is a low-cost magnet-free motor, also suitable for mass production and able to reach good performance and meet the demanding requirements typical of an electric car. An innovative asymmetric rotor with “fluid-shaped” barriers has been designed with multiple ribs that connect the rotor segments to each other axially and transversally. The motor performance has been evaluated over the full speed range by a finite element tool and for the Worldwide Light Vehicles Test Procedure (WLTP) Class 3 driving cycle.

This work addresses some aspects concerning the practical implementation of a method to estimate the steady-state performance of three-phase induction motors. The method requires only the acquisition of stator voltages and currents data during a no-load startup test taken at the final stage of the production line. The first step of the method implemented consists of estimating the parameters of the single-cage model considering both the rotor resistance and leakage inductance variable with slip. In the second step, the steady-state performance is determined using the equivalent circuit and the estimated parameters, thus allowing the motor manufacturer to check if the motor meets all the requirements stated by national and international norms. The main interest here resides in the starting characteristics such as locked-rotor torque and starting currents. Accordingly, to improve the accuracy of the results, some aspects related to the locked-rotor condition were investigated, namely (a) the influence of variations in the voltage amplitude, in particular the voltage drop during the first cycles, on the magnetizing and leakage inductances, (b) the influence of the mathematical expression chosen to model parameter variations with slip, and (c) the impact of the ratio considered between the stator and rotor leakage inductances. Finally, practical results obtained with estimated parameters are discussed and compared with results obtained with calculated parameters.

For high-power permanent-magnet synchronous machines, the efficiency is usually in the range above 95%, where for a direct efficiency determination the measurement error gets too big. An alternative approach of indirect efficiency determination allows a bigger accuracy. It is done by the summation of individual losses, i.e., current-depending and additional load losses, iron losses, and additional losses caused by inverter feeding. These loss groups are determined at no-load and removed rotor operation. At power ratings below 200 kW the efficiency usually not exceeds 95%, so the proposed indirect method can be compared by the direct method experimentally. This comparison can be done also by numerical methods theoretically without an efficiency limit. In this context, five different permanent-magnet test machines, within the power range from 45 kW to 160 kW, were used to investigate the influence of the stator and rotor design on the losses and on the efficiency determination. For the test machine with a rated power of 160 kW and distributed fractional-slot stator winding, the indirect procedure is shown in detail via no-load, removed rotor, and load measurements for different rotor speeds. For this test machine, a quite good agreement between direct and indirect efficiency values was achieved for motor and generator operation, with deviations of less than 1 percentage point. For the other four test machines, measured loss and efficiency values were compared to simulation results at sinusoidal current feeding. Especially for those permanent-magnet synchronous machines with distributed stator winding without any sub-harmonic stator field waves, the proposed indirect efficiency determination method demonstrates to be a useful alternative to direct efficiency determination. For special machine designs with sub-harmonic stator field waves, caused by fractional slot windings, higher additional rotor losses may occur, which are not considered by the presented method. Therefore, the indirectly determined efficiency values for those machines show higher deviations up to 2 percentage points compared to the direct method.

Most of the electric induction motors installed in Central America have been imported, due to not having manufacturing plants in this region, manufacturers prefer to import them from other neighboring countries such as Brazil, Mexico, etc. The main disadvantage of this situation is that the motors are manufactured with voltages different from those existing in the country or region where they will be installed. Although the motors have tolerances recommended by both the NEMA and IEC standards for power quality disturbances, voltage variations (VV) will have an impact on the efficiency and consumption of electric motors. Given this scenario, the present work aims to analyze four voltage variation conditions present in Central América on electric induction motor classes IE2, IE3, and IE4, the last being the line-start permanent magnet motor. This work addresses the influences of voltage variation on consumption, power factor, and temperature. Where a decrement in power factor, and an increment in consumption and temperature were observed for the overvoltage conditions, for the undervoltage, an increase in power factor and variations in consumption and temperature according to the motor class were observed.

Line-start synchronous reluctance motors are hybrid motors that simultaneously have the advantages of synchronous reluctance motors (high performance, simple construction, low cost of materials, constant speed at variable load) and induction motors (IM) (mainly the ability to start if supplied directly from the mains).Scientific literature (Gamba et al., International Electric Machines & Drives Conference, Chicago, 648–655, 2013) has widely affirmed that these types of motors, although requiring less quantities of active material (magnetic lamination, copper wire, die-cast aluminium) to obtain the same efficiency class (for example IE3 or IE4) of induction motors, have reduced performance in the start-up phase, and especially in the critical synchronization phase. In particular, with the same load torque, the synchronization capability decreases with the increase in the load inertia. This new design is therefore focused on minimizing this weak point, thus obtaining a series of motors that can be usefully put on the market for most of the applications to replace induction motors. The presentation of the experimental test results on prototypes confirmed the very great potentials of the calculations, and they were strategic in the decision to place these motors in the market and start-up their series production.

Optimizing system efficiency for motor-driven fluid handling equipment continues to be a major source of cost and energy savings for owners and operators of pumps, compressors, blowers, fans, and other rotating equipment. Recent legislation such as the Ecodesign requirements for water pumps and the United States Department of Energy (DOE) legislation focused on specific types of pumps or fans sold in the USA to offer new energy efficiency metrics for purchase of new equipment. The method of True Weighted Efficiency (TWE) was later developed to offer a single efficiency metric applicable to any rotating machine operating under multiple operating conditions. These methods are valuable and confidently applied to extended products. Most energy savings opportunities apply to existing installed systems. Pumps are often oversized to accommodate worst case design conditions leading to suboptimal efficiency at normal operation. Further, operating conditions change over the lifespan of a pump system, often justifying the replacement or retrofit of the existing system with new pumps or system control methods. This requires energy efficiency analysis of the entire system, including the extended product (pump, motor, and control system) and the accompanying piping system network. These problem domains are typically analyzed separately using piping system analysis software, a pump selection optimization product, and calibration with operating data acquired over a specified time horizon. This paper examines pipe system analysis integrated with the actual selection of alternative pump-motor-control systems. A digital twin of the existing pump and piping system is developed and empirically adjusted to accurately model the actual performance data provided from on-site sensors. Once the digital twin is accurately calibrated to field sensor data, different system design modifications are evaluated to assess alternative energy-efficient scenarios. Three case studies are used to demonstrate a pipe system analysis with integrated pump selection to optimize the pump system and piping network. The goal of the paper is to promote awareness and broad application of this integrated method for industry practitioners working with motor-operated fluid handling equipment.

When lines of constant specific energy for a variable-speed rotodynamic pump are presented on a differential head verse flow-rate graph, the result is a set of eccentric, inverted, parabola-like curves. In this paper, these lines are referred to as specific energy shells. It will be shown that energy consumption per unit volume pumped is not necessarily proportional to efficiency or speed for any given pumping system. However, specific energy shells give immediate insight into relative energy efficiencies across the entire range of flow rates. To demonstrate, a desktop case study will be presented where the reduction from speed control alone will be quantified, and the methodology will be repeated with a moderate passive system improvement. The result is a reduction in specific energy as pump speed is reduced despite a decline in efficiency. Secondary to this, as the pump speed is reduced further, the efficiency continues to decline while the specific energy increases, demonstrating that using speed reduction as a tool to reduce energy consumption has limitations that are pump- and system specific. Finally, it will be shown that specific energy has the same affinity relationship with speed as differential head E S 1 E S 2 = n 1 n 2 2 = H 1 H 2 $$ \left(\frac{{\boldsymbol{E}}_{{\boldsymbol{S}}_{\mathbf{1}}}}{{\boldsymbol{E}}_{{\boldsymbol{S}}_{\mathbf{2}}}}\right)={\left(\frac{{\boldsymbol{n}}_{\mathbf{1}}}{{\boldsymbol{n}}_{\mathbf{2}}}\right)}^{\mathbf{2}}=\left(\frac{{\boldsymbol{H}}_{\mathbf{1}}}{{\boldsymbol{H}}_{\mathbf{2}}}\right) $$ . The purpose of the case study and affinity relationship presentation is to demonstrate that the variable speed pump performance graph with specific energy shells overlaid can be used to estimate all of the pump-specific findings shown without further calculations required. This capacity is not available using the information traditionally presented on a variable speed pump performance graph. Therefore, specific energy shells should be included as an option on variable speed pump performance graphs, and pump package providers should work toward including all component efficiencies in a single graph.

Pumps are among the largest energy consumers in industry and in the household sector. Across the EU, pumps consume 22% of electric motor energy. It has been shown in the literature that a defective motor can not only lead to higher breakdown times, but also to a decrease in motor efficiency. In an application such as a centrifugal pump, further types of faults can appear, such as dry-running, hydraulic blockage, clogging, or cavitation. According to the state of the art, it is not known how much these individual faults influence the efficiency of a pump unit. To address this problem, two types of centrifugal pumps, a dry-runner and a wet-rotor pump, were measured in a pump test bench. The dry-runner pump was driven by a mains-fed induction motor with a power of 1.1 kW. For the wet-rotor pump, a frequency converter-fed permanent magnet motor with a power of 800 W was used. The test bench was equipped with flow and pressure sensors and control valves. The electric power was measured by high-precision power analyzers. In order to evaluate the data, a standardized procedure was used that not only considers the efficiency at one single load point but also the efficiency of part load points and different operating times. The answers provided in this chapter will help plant operators, in particular, to better plan the maintenance of their centrifugal pumps. By comparing different faults for different types of centrifugal pumps, this experiment represents another step in the research to evaluate the energy efficiency of faulty pumps.

In the context of centrifugal pumps, the term cavitation implies a dynamic process involving the formation of bubbles inside the liquid, their growth and their subsequent collapse as the liquid flows through the pump. Generally, the bubbles that form inside the liquid are one of two types: vapor bubbles or gas bubbles. Cavitation usually occurs in pumping systems, where it aggressively damages the pump if it is not detected correctly and at the right moment. Its impact results from a lack of pressure at the suction line of the pump, which forms air bubbles that implode inside the core of the pump. Cavitation causes an alteration of pump characteristics, mechanical damage, noises, and vibrations that can lead to complete pump destruction. Moreover, if the pump is not destroyed, cavitation reduces its life expectancy and increases maintenance costs. In this chapter, we will present the causes and consequences of cavitation and the solution to detect cavitation, and we will develop our proposed solution on the basis of correcting the net-positive suction head required for the change in pump characteristics resulting from mechanical wear.

The chapter explores the distinction between energy efficiency and energy saving, emphasizing the importance of proper product operation over mere energy conservation. By adopting an Extended Product Approach (EPA), industry aims to meet efficiency standards, but also to maximize energy savings. This approach involves integrating components like pumps, motors, and frequency converters into a cohesive system, optimizing their collective performance. Through EPA, significant energy savings of up to 40% can be achieved, primarily by adjusting equipment speed rather than throttling pumps. The chapter underscores the importance of legislative support for EPA adoption, highlighting its potential to revolutionize energy efficiency in the European Union and beyond.

Responding to criticism from other stakeholders, the European fan industry acknowledges a need to provide additional data describing the energy losses at partial-load operation. Rarely is a fan used at its best efficiency point. Standardization is required that describes the performance characteristics at other operating points. Standardized methodology can then be used by regulators to legislate product information requirements. This would also provide users with reliable data to make better informed decisions. This paper describes proposals from the European fan industry for a European standardization request (sReq) to revise or create a new standard.

The performance of a driven fan can be determined either by direct measurement or by calculation. In both methods, the ratio of the fan air power (output power) and the electrical input power determines the efficiency. A direct measurement will include the losses of all the components in a fan system, and the effects of those components on the fan system. The calculation methods may not include all the components necessary to build the final fan assembly. Furthermore, some components can have an adverse aerodynamic impact that is not included in the calculation. This paper discusses those potential missing elements. When the driven fan is a simple arrangement, a calculation will give a similar result to a direct measurement. Where a simple arrangement is of a motor directly connected to the impeller, and the motor is located outside of the air stream. However, the arrangement is not simple, and some components can add losses by causing aerodynamic disturbance. The two calculation methods in fan standards do not include losses due to obstructions caused by the components of the fan. This was recognized by European legislators that added a compensation factor in their calculation, but this is disadvantageous in some fan arrangements and possibly is not enough to take other elements and effects of other fan arrangements into consideration. A more pragmatic approach is required in standards and legislation. They must define when a calculation method is appropriate, where care should be taken and where only a direct measurement should be applied.

In order to reduce the energy consumption of electric motor driven systems (EMDS), single components of these EMDS have been regulated regarding their efficiency. By introducing the extended product approach in DIN EN 61800-9, compressors have been reduced to simple load machines of power drive systems (PDS). This suggests the need to improving the component efficiencies even more and to link the PDS efficiency to the compressor package, instead of considering the overall energy consumption of the application, process, or system, which includes the complete compressor package. A comparison of motor efficiency with compressor package efficiency using the same electric motor but different compressor technologies is given and reveals that the efficiency of a compressor package primarily independent of the EMDS when looking at the total operating range. Three practical examples are given to emphasize the application-oriented wire-to-process overall performance as the key measure of the package. The various possible operation modes of not only a single compressor package but also even a whole compressed air station have to be taken into account for a holistic point of view. The paper concludes that a life cycle and application approach is the most efficient way forward toward real energy savings.

Compressed air is a widely used energy carrier; however, its production is associated with a low energy efficiency. The utilization of isobaric compressed air receivers can increase the storage capacity significantly while simultaneously lower the energy demand. In this work, we propose a novel concept of an isobaric compressed air receiver based on pressure equalizing modules (PEQM), which combine different phase change materials for maintaining constant pressure as well as for storing heat. The PEQM can be placed into the receiver, and by the interaction of many modules, compressed air is stored isobarically. In a test plant, which emulates a compressed air system (CAS) with a fixed-speed oil-injected rotary screw compressor, a dryer, and a 250 l compressed air receiver, energy measurements are conducted. Since a pressure range may still be required for control purposes, the investigations in this paper are carried out within a pressure range of 2 bar. Based on the experimental results, the potential energy savings, due to equipping the receiver with PEQM, are determined theoretically. Approximately, 995 PEQM are fitting inside the receiver. They increase the storage capacity by 58.5% in a pressure range of 2 bar and lead to energy savings of around 9%. A major reason for the lower energy consumption is the stopping of the compressor, as the larger storage capacity allows more air to be used for a longer period of time. Based on that, isobaric compressed air receivers for CAS with fixed-speed compressors could be a promising measure to improve energy efficiency and should therefore be further developed.

Small and smart sensors have become popular and can be found embedded in a variety of applications. The evolution of the storage capacity, data processing, and connectivity of the sensors provided their intense use in the most different domestic and industrial applications. The exponential increase of collected information by these sensors has generated a demand for efficient data analysis techniques in order to assist the end user in decisions that are more assertive. Within this context, different manufactures launched intelligent sensors in the last year that use machine learning techniques to analyze the vibration patterns exhibited by electric motors during operation. From learning the motor normal vibration pattern, such sensors are able to identify, independently and without human interference, vibration problems by changes that happen in the operational pattern of the monitored electric motor. The purpose of this paper is to present an experimental verification of this diagnosis reliability. In this way, an agreement statistical method was used, in which one specific type of smart sensor was challenged in a “blind test” to identify two types of failure such as unbalance and misalignment. The results presented by the smart sensor were then compared before and after the fault imputation using the mentioned statistical method. To guarantee the reproducibility of the results, more than 15,000 measured data were collected in a controlled environment, inside the ambient of a research laboratory, totaling 120 operational patterns (between balanced, unbalanced, aligned, and misaligned) in a set of 60 motors of different types and sizes. The agreement index reached 92% between the generated fault and the smart sensor diagnosis.

Digitalization brings “smart” applications to all kinds of industrial energy systems, of which electric motor-driven systems take the largest part of the industrial electricity use. Electric motor-driven systems (EMDS) are currently responsible for some 53% of global electricity consumption (IEA 2017), and approximately 70% of the industrial electricity use. Data analytic skills are quite different from the skills required to design and optimize electric motor-driven systems. In the transition of a motor system into a “smart” system, the manufacturers of the main components have a strong position. With the integration of a smart motor-driven system, the motor-driven system’s provider uses its own dedicated platform. For the end user, this means a vendor lock-in is created. The integration itself and especially this specific issue requires new skills such as IT architecture skills and knowledge of middleware and standards. For the needed capacity building by suppliers, service industry and end users needed to achieve the envisaged digitization of motor-driven systems, training and education can already be found in the market, but these initiatives are not transparent, bundled nor fully effective. Research is defined and executed to assess the skills needed and routes for capacity building for the digitization of motor systems in the industry. The research starting point is an ecosystem analysis performed toward digital sensor systems for electric motor systems with a deep dive into the skills needed. Analysis routes are defined for developing the skills needed among professionals. In parallel, so-called multidimensional use cases are developed to inspire the market to accelerate the adoption of skills and underlaying digitalized systems. Our research is based on interaction with Dutch knowledge institutes, industrial end users, service industry, and sensor manufacturers. Research is being performed for the Dutch Topsector Energy, program digitalization. In this paper, we describe the major societal, political, labor market, economic, and environmental trends that provide the context for the digitalization possibilities and barriers of electric motor-driven systems. We describe in some detail the skills set per type of organization (technology provider, end user, and maintenance provider). We describe some specific challenges with respect to the complete technology innovation system of digitalization of EMDS. With respect to the digital skilling agenda, we focus on learning activities in networks and on a mix of learning activities to match individual learning needs.

The consequences of climate change are increasingly noticeable in everyday life and require consistent and immediate action. A multitude of legislative restrictions regarding the permissible emission of pollutants in the transport sector requires a redesign of the powertrain architecture. The focus on hybrid and purely electric drive concepts boosts the demand for electric motor development and testing. The electric motor is the central component in the electric powertrain. Consequently, its efficiency is a significant lever for improving overall vehicle efficiency. A large part of the energy losses in the electric motor is due to the electrical resistance. The electrical conductivity of the windings is temperature-dependent, making thermal management crucial for the efficiency of the electric motor. Furthermore, thermal management has significant influence on the health condition and the expected lifetime of the electric motor. By analyzing and evaluating the temperature distribution, damage-relevant operating points can be identified and avoided in advance. The determination of a continuous temperature distribution opens up new possibilities for condition-based maintenance as well as the development of innovative operating strategies. A consistent temperature distribution within the motor map is the foundation for optimal electric motor efficiency. Depending on different load collectives and operating modes, initial experimental investigations on the test bench have shown that different temperature distributions occur within the motor map. The application of machine learning algorithms enables the prediction of the temperature distribution. This includes, on the one hand, the identification of critical temperature areas and, on the other hand, the identification of potential temperature peaks depending on the driving cycle. The overall goal is to determine a continuous temperature curve over the entire motor map. By using a few temperature measurement points in conjunction with suitable machine learning algorithms, results can be obtained regarding the temperature distribution at any point in the motor map. By applying and subsequently comparing standardized machine learning algorithms the most suitable algorithm is determined.

In many production-related applications, electromechanical drive units with gear motors are not maintained in a condition-based manner. The worsening system conditions lead to deterioration in efficiency and effectiveness with an increasing operating time. Vibration measurements, as well as the current signals of an electric motor, offer the possibility to monitor the condition of gear motors. In laboratory environments, the generation of fault conditions is difficult because this often requires long operating times. For this reason, the measurements are carried out on a gear motor in new condition and on a field return, which was used under real operating conditions in production. Different operating conditions of the drive units represent the conditions in real production environments and have an influence on the state variables “vibration” and “current”. Therefore, the different operating conditions must be considered to ensure reliable monitoring of the system state. To enable a fault detection with a multi-input artificial neural network (ANN), preprocessing of the recorded vibration data with an envelope demodulation is necessary for highlighting the relevant signal components. Only the maximum current values per operating and system condition are considered. The consideration of the current and vibration signals improves the accuracy of condition diagnosis.

Central America is a region with great potential for energy efficiency, which, however, has not been fully exploited. Lack of knowledge, policies, and incentives represent the main challenges and barriers for the implementation of Minimum Energy Performance Standards (MEPS) in induction motors (IMs). This chapter analyzes the current scenario of electric motors, comparing it with international experiences, as well as giving recommendations for the implementation of MEPS in the region. Considerations to be taken into account for substitution by end users are also made considering the voltage differences due to the importation of electric motors and the countries nominal voltages and finally an economical comparison of the payback variation with different voltage variation conditions.

With the amendment of ISO 50001 to the 2018 version of the standard, some topics within an EnMS came into greater focus, such as the energy performance indicators (EnPIs). Since then, many experiences have been gained in this regard, which will be presented in the lecture. After answering the question “when and for what are EnPIs necessary?,” the next challenge within an EnMS is “In which context is which indicator recommended?” Basically, the first indicator to think of is “energy consumption per product produced,” unless the SEU (significant energy use) is not directly involved in the production but performs peripheral tasks (this case is explained by means of an example), or the energy consumption is independent of the produced quantity (another example). Once the appropriate EnPI has been found, the requirements for normalization from subsection 6.4 of ISO 50001:2018 should be observed (although normalization must only be carried out IF data is available that indicates the effect of relevant variables! This case is also explained by means of an example). With regard to given needs for normalization, the following examples from the recent past will be presented and explained in the lecture: product mix, base load, temperature, and capacity utilization

Based on four consecutive annual market surveys in Switzerland, continuous progress in sales of efficient motors, variable frequency drives (VFD), pumps, and fans can be monitored. Similar developments have been observed with less detailed data in the European market. The Swiss Federal Office of Energy (SFOE) is responsible as regulator for establishing Minimum Energy Performance Standards (MEPS) and conducting market surveillance in Switzerland. SFOE has established a market monitoring program for a wide range of energy-using products. Since 2017, the market analysis for industrial products (motors, VFDs, pumps, and fans) was mandated within the Swiss Topmotors program ( www.topmotors.ch/en ) to Impact Energy, Zurich, in collaboration with the international market research company OMDIA. The market survey for these products that have to follow Swiss MEPS (synchronized with the respective European Ecodesign regulations) is based on direct surveys of and interviews with relevant manufacturers and importers. The subsequent energy efficiency analysis is the basis for the annually published Topmotors Market Report. The Topmotors Market Report presents an overview of the continuous development of the efficiency, numbers, poles, and size of low-voltage electric motors with a nominal power from 0.12 kW to 1000 kW sold in Switzerland from 2016 to 2019. The most recent 2020 edition of the Topmotors Market Report covers the market in 2019. It reports on Swiss market sales of motors, pumps, fans, and VFDs. Specific average selling prices are reported in comparison with the preceding year for motors (0.7%) and VFDs (1.1%). The impact on annual electricity consumption of the replacement of inefficient old motors by new ones is estimated at savings 120–200 GWh of electricity in 2019. Furthermore, the development of the market is analyzed based on the collected data of the four consecutive years from 2016 to 2019. For example, the market share of Super Premium IE4-motors rises by 46.4%, and the average efficiency of sold motors rises by 0.175 percentage points. A cost-benefit analysis indicates that under current market conditions in Switzerland (2019 motor prices and electric energy costs), electric motors of 0.5 kW to 500 kW in industrial applications under regular load conditions are typically more cost effective in the efficiency class IE4 than IE2- or IE3-motors. For the market in the European Union (EU), sales figures of motors, pumps, and fans are reported. Total sales amount for motors in 2019 to 7.6 million units. According to sales figures from CEMEP, the European Committee of Manufacturers of Electrical Machines and Power Electronics, IE3-motors are leading with a market share of 59%.

There is no way to reach the objective of a circular economy by dealing separately with the energy efficiency performance and other environmental objectives like with material efficiency aspects. Optimal trade-offs balancing different constraints impacting environment and sustainable economy are keys for consideration. The now-published Ecodesign Regulation (EU) 2019/1781 applicable to electric motors and variable speed drives (VSD) asks for compliance with mandatory minimum energy efficiency performance. The European Commission will start soon the revision process of this regulation for considering additional resource efficiency and will report on a proposal for discussion with stakeholder considerations for a finalization stage starting from November 2023.There are many published and current research works conducted by institutes, the European Commission Joint Research Center, or by professional manufacturer associations on this topic. A new one is the anticipated standardization work initiated by the CENELEC Technical Committee 22X for Power Electronics, dealing with “Methods and Specifications for the Assessment of Material Efficiency of Variable Speed Drives”. This work would consider the existing EN 50598-3 standard on product-specific rules for life cycle assessment and content of environmental declaration. In addition to other existing standards and regulations applicable, the VSD industry will benefit from tools helping them to reach sustainability objectives like with the United Nations’ Sustainable Development Goal 12 (Responsible Consumption & Production) and other SDGs 3, 6, 13, 14, 15 impacted by SDG 12.This chapter, as a follow-up of a previous EEMODS’2019 paper, will provide an update of the published series of nine EN 4555x CEN/CLC European standards related to the “General Methods for Assessment of Material Efficiency Aspects for Energy-Related Products”. It will particularly focus on the CENELEC initiative to derive these horizontal standards to adapt and apply them to the variable speed electric power drive systems and to consider the overall Environmentally Conscious Design (ECD).It will also focus on energy efficiency and material efficiency-related data to be operated by all stakeholders along the complete product and systems’ life cycles. The chapter will describe the need to make material efficiency and energy efficiency information available, interoperable, and usable through the whole life cycle. A digital catalogue data, including material efficiency properties, should be a key tool for ensuring interoperability between digital twins, requesting data exchange between equipment, design, manufacturing, or facility management tools for different operators who ask for an effective environmentally conscious digitization in Circular Economy.

Electric motors are a widely used equipment capable of transforming electrical energy, consuming a significant part of the electrical energy in industries. With the advancement of technology in recent decades, electric motors have become more efficient and sustainable reaching efficiencies of approximately 96%; however, the presence of electrical power quality disturbances can negatively affect the operation of these machines, increasing their losses and consequently decreasing their efficiency. Based on this context, this work aims to compare the frame thermal variation in IE2-, IE3-, and IE4-class motors, the latter being a line-start permanent magnet motor, connected in grounded star and in triangle under second-, third-, and fifth-order harmonics through 3D thermographic maps obtained from thermographic images. For the measurements, an AC three-phase power supply FCATHQ™ model was used, capable of generating pure sine waves and electrical power quality disturbances of various magnitudes, the data were collected through an infrared camera from the manufacturer FLIR model T620 and the linear load was imposed to the electric motors through a Foucault brake. The three electrical machines analyzed under harmonics are stressed until they reach their thermal equilibrium; the collected data are processed and then analyzed. The results show which harmonic order most impacts on each motor efficiency class, which area of the motor frame is most affected to get a sense of how different harmonic orders impact the internal components and materials of each motor and what is the thermal behavior of each connection for different voltage levels.

Energy efficiency is identified by the United Nations as the key factor for strengthening the energy security, protecting the environment, as well as contributing on sustainable development goals. Within this context, IEC via standardization enables technology transfer and promotes different efficiency solutions and services in a global level. It is the IEC Standards that provide the basis for testing, certification, and measurement of efficiency of energy using/relating products; this is also applied to electric drive/motor systems. Energy-efficiency improvement is supported through a systematic selection of the most efficient converter and drive system technology via the IEC 61800-9 series. In parallel, the recently published regulation EU 2019/1781 refers to minimum efficiency requirements for the direct-on-line motors and variable speed drives, namely, frequency converters. This chapter addresses the trends in eco-design standards for drive system components and focuses on the innovative points to be included in the forthcoming edition of the IEC 61800-9-2. Especially, the scope of IEC 61800-9-2 is updated by providing the efficiency evaluation and classification of frequency converters with extended functionalities in respect to the reference complete drive module. Correction factors are introduced to adapt the reference system losses rather than new models. Completing all recent activities in eco-design standardization, the recently published IEC 60034-2-3 is discussed that specifies loss determination methods for converter-fed AC motors.

In September 2020, Egypt’s Minister of Trade and Industry signed a Decree that introduces mandatory IE3 efficiency standards for electric motors across Egypt from May 2022. Change is essential for economic and environmental reasons, since a survey of over 100 motor-using factories and businesses showed that three quarters of installed motors were of poor or unmarked efficiency. The Decree sealed a collaborative process that began in 2016 to devise and implement a program of preparation and market surveillance capacity building. This chapter traces the path of the process, involving a seven-stage roadmap agreed with industry stakeholders, its challenges and solutions, and critical risks—some resolved, and others remaining. The seven-stage process could be applied to policy development in other emerging economies: first, establishing overall political and organisational leadership through institutional analysis and engagement and second, establishing national technical standards based on international norms. A key third stage was devising a timing scenario for implementing minimum energy-efficiency performance standards (MEPS) that was acceptable to stakeholders. Analysis of this scenario by US Lawrence Berkeley National Laboratory projected savings in Egypt of US$ 560 million Net Present Value from the 2016 base to 2031 and 3 TWh saved annually, with avoided investment in 1100 MW of new power generating capacity. Fourth was consulting with the private sector, understanding needs, perceptions (or mis-perceptions), raising awareness and building consensus. The biggest challenges were in the fifth step: to plan for effective market surveillance, including a new test lab and building capacity of market inspection authorities. The International Finance Corporation, a member of the World Bank Group, led additional supporting initiatives as part of a sixth step to help upgrade equipment supply chains to deliver and assimilate better motors. Review of program performance is the seventh step. This paper concludes with lessons learned, aiming to inspire and inform further replication.

This work analyzes the world’s scientific production on energy efficiency in motor systems through bibliometric indicators. Bibliometrics is a method of quantitative analysis for scientific research, where data express the contribution of scientific knowledge from publications in certain areas. Production indicators are helpful for the planning and execution of public policies and the scientific community’s knowledge of the system it operates. In this way, bibliometric analysis can identify the primary means of publishing materials in the research area, the principal researchers, the leading research groups, among other possibilities. For this research, the search engine “Scopus” was used in the search in titles, abstract, and keywords, by Energetic Efficiency AND Electric Motors AND Energetic Policies, considering 30 years of production, from 1991 to 2021, published in English, being Journals Papers, Journals Reviews; Conference Articles, Conference Reviews. In the first 10 years analyzed (1990–2000), research focused on discussing the impact of Minimum Energy Performance Standards (MEPS) and the replacement of conventional electric motors with high efficiency motors. In the next 10 years analyzed (2000–2010), surveys showed concerns about advances in MEPS levels and in the efficiency of the electric motor and the driven load. In the last 10 years analyzed (2010–2020) researchers focused their research on electric mobility, and in the case of stationary motor drive the focus was on the entry of technologies present in Industry 4.0, such as Internet of Things, artificial intelligence, intelligent detection, pre-diagnosis, etc.

Electric motor-driven systems (EMDS) are responsible for approximately 53% of global electricity consumption (IEA 2017). Optimal interaction of the respective components toward an integrated system is a prerequisite for large energy savings in operation. The design of components, their sizing and selection, and their match to form an optimal system, together with well-controlled operation, need a series of aligned agreements. In 2019, the IEC Advisory Committee on Energy Efficiency (ACEE) launched with its Task Group 6 the CAISEMS project. It tries to apply the principles of systems’ approach in EMDS as outlined in the IEC ACEE Guides 118 and 119 through the instrument of Basic and Group Publications, promoting the collaboration of involved Technical Committees (TCs) to improve the overall energy efficiency of the entire EMDS. About ten different IEC and ISO TCs cover the components of an EMDS, such as controllers and switchgear, converters, motors, belts and pulleys, gears, and the eventual application in pumps, fans, and compressors, etc. The match of all these components at full load and any other load requires a clear strategy of testing, calculation, and interpolation methods, as well as proper guidelines for sizing of the multiple components. To avoid multiple testing and certification efforts for the manufacturers, a common approach with an integrated alignment and coordination of all these performance aspects is needed. Where, for example, for fans, the system performance can be determined accurately using ISO 5801, a calculation from component parts can result in significant variations. Aligning the component standards for fans to wire-to-air standards and equally for pumps to wire-to-water standards needs to include all the losses that occur when components come together as a system. A first survey of some 37 standards for IEC and ISO energy-efficiency publications in EMDS shows the status quo of standardization and the open needs for further clarification and coordination. This coordination effort will benefit the manufactures of individual components, the system integrator, the industrial user as well as the government regulator, and the market surveillance authority. The launch of the CAISEMS project with the above-mentioned stakeholders took place as side event of EEMODS’19 in September 2019 in Tokyo at JEMA headquarters. In October 2021, the CAISEMS project group has converted into an official IEC and ISO Joint Advisory Group, including at the outset IEC TC 2 (motors), IEC TC 22 (converters), and ISO TC 117 (fans). This newly formed IEC and ISO JAG 22 has started to work on the path toward a widely accepted guideline for well-coordinated and energy-efficient EMDS. The IEC ACEE has lent itself as the platform between these and other interested TCs that will want to join JAG 22 to organize what eventually might evolve toward a Basic Standard for the horizontal energy-efficiency aspects of many kinds of different EMDS. In this article, we describe the major societal, political, labor market, economic, and environmental trends that provide the context for the digitalization possibilities and barriers of EMDS systems.

The use of adjustable speed drives on motor-driven systems—power drive systems (PDS)—offers possibility for dramatic energy savings in commercial and industrial applications beyond what can be achieved by increasing the efficiency of individual components. However, the adoption of PDS remains limited because of the perception that only variable load (VL) applications can benefit from the energy savings potential. This viewpoint, however, fails to consider other energy savings mechanisms and non-energy benefits that come from the installation of a PDS. This paper leverages recent collaborative work by the Northwest Energy Efficiency Alliance and the National Electric Manufacturers Association (NEMA) to examine how and where PDS are currently being installed, as well as quantify and characterize the potential energy savings associated with PDS in a range of applications—including both inherently variable and inherently constant load cases. The work also characterizes other benefits associated with PDS that, though not directly related to the efficiency of the motor system’s operation, can often have a larger monetary impact than the energy savings. This work suggests significant potential benefit from PDS that are not currently being fully realized in the market and outlines steps that the market can take to help breakdown myths around where PDS “make sense,” including the introduction of a new metric for PDS–Power Index in NEMA MG 10011: Power Index Calculation Procedure—Standard Rating Methodology for Power Drive Systems and Complete Drive Modules that describes the potential energy savings possible from both constant and VL systems.

The test method described in IEC 61800-9-2:2017 (edition 1) for converters (and in IEC TS 60034-2-3:2013 for motors driven by converters) has not been used for sufficient time to know their accuracy and repeatability. At its meeting on 6 September 2017 at EEMODS’17 in Rome, representatives from IEC TC 22/SC 22G/WG18, 4E EMSA and several independent testing labs (“project group”) decided to have 4E EMSA to undertake the project leadership and the organization of a round robin exercise for converters cooperation with IEC WG18. During the round robin exercise, which was launched in the fall of 2019, Denmark, together with Switzerland, was responsible for the organization, monitoring, and documentation of the interlaboratory test for converter losses. A total of 8 from the originally 11 laboratories were even able to perform a total of 172 tests on 52 different converters. The power range within participating laboratories was limited to the range between 0.12 and 55 kW. The results of the Round Robin Converters (RR’C) do build key evidence for the revision of IEC 61800-9-2 ed. 2, especially the design of an updated and solid testing procedure which will also presented, and the provision of sufficient solid and impartial measured background data for the correction of the current level of the reference values for losses inside converters for further revisions of the standard.

In recent times, industry has seen significant vibration issues for two pole motors when tested in field and more specifically in petrochemical industry where we need to meet stringent IEEE 841 (Standard, IEEE, 841: IEEE Standard for Petroleum and Chemical Industry. IEEE, 2021) vibration limits leading to increased costs associated with rework and warranty, thereby causing further delay to end customer’s project timelines and costs. Traditional methods to resolve 2P vibration issues involved trial and error methods, which is time consuming, non-validated simulation models with high test to design error, and unstructured approach to reduce vibrations. Hence, we need a structured root cause analysis and modified and validated mathematical models to simulate and estimate the system natural frequencies to understand system resonance issues and predict vibration amplitudes before testing, thereby reducing the issue resolution time and costs.This chapter highlights the systematic approach to understand and find root cause analysis to resolve the high vibrations caused due to twice line frequency vibrations in 2-pole induction motor on rigid base. Developed simulation models to estimate natural frequencies using modal analysis and to predict vibration amplitudes at 2F using harmonic analysis and validated with test results to reduce the simulation errors to less than +/− 5%. Lessons learnt from modified FEA boundary conditions, motor component and assembly-level interactions, sensitivity analysis due to bolt types, torque, rigid and flexible bases, soft foot, bearing and rotor system, structural stiffness, etc. helped to refine simulation model for better prediction of motor natural frequency using harmonic analysis to estimate the vibration amplitudes.In addition, for a similar phenomenon in 2-pole medium voltage motors with fabricated rotors where rotor axial/radial ducts are extensively used for cooling and reducing some weight, vibration amplitudes at 2F due to magnetic asymmetry could be observed. These rotor ducts can lead to false positive rotor duct fault, produced for healthy motors, which is an ongoing problem in the industry. There is no practical solution to avoid this unnecessary maintenance cost. In this paper, developed approach was adopted for predicting natural frequencies and vibration amplitudes for 2-pole medium voltage induction motors having NEMA 580 frame size and ducted rotor construction and then validated with test results. Sensitivity analysis due to ducted rotor construction and stack stiffness helped in understanding influence of rotor ducts over vibration amplitudes. Refined mathematical models helped significantly to resolve considerable vibration issues for 2P motors on rigid base.

Optimizing industrial electric motor systems can deliver substantial benefits for their users as well as their stakeholders, especially as governments are developing new more stringent energy and climate policies, including energy efficiency (savings) and CO2 emission reduction goals. In the Netherlands, initiatives are in operation to support industry in developing activities to meet these reduction goals. In this presentation/paper, a programmatic approach for motor systems ‘Pilot audit program on electric motor systems’ is presented, including its concept, results, lessons learned, as well as some financial and economic data. In parallel, two other initiatives targeted at energy-efficient motor systems will be included, e.g., the concept of financial services through energy service companies and the inclusion of efficient motor-driven systems into Dutch environmental regulation through some specific measures for large industrial companies. The latter addresses customized measures, where The Netherlands has a large base of process industries, such as chemical industry, and refinery and steel industry. Special attention is into lessons learned, where, e.g., some main barriers within industry appear to be limitations of internal resources, lack of available CAPEX for energy-efficiency projects, and the availability of data on a sufficient detailed level. On the supply side, i.e., service industry and energy advisors, a lack of resources, tools, and focus (on the systems) can hinder a quick rollout as well. The development of different IT-related tools and suppliers offers new opportunities for the service industry, industrial end user, and energy advisors. The field of predictive maintenance, energy baselining and monitoring, advanced process control, and system optimization do have overlaps, but above all, offer new extra opportunities for analysis, development of economic business cases, and continued improvement of the installed base’s performance. Some examples will be presented as well. The presentation will include the audit program results and accompanying schemes and will include a short perspective into the comparability of regulatory measures and the more voluntary intrinsic motivators within industry.

Vertical motors are normally used for pump applications. In general, the pump is located in the well casing and is driven with a long shaft that is coupled to the motor shaft by one of the various available couplings, i.e., bolted, self-release, or non-reverse couplings. Of these couplings, in cases where reverse rotating protection and upthrust handling ability are required, a non-reverse coupling is offered. A non-reverse coupling typically consists of Non-Reverse Ratchet (NRR) which is mounted on either the upper half coupling or the lower half coupling of the motor. An NRR mechanism protects the pump and pump motor from damage caused by a falling water column driving the pump in reverse direction after the motor is shut down. It also prevents the motor from driving the pump backwards which could cause the pump shaft to unscrew at the joints. The NRR mechanism allows the rotor to rotate in the correct or desired direction and locks the rotor rotation when it reverses. An NRR mechanism consists of ratchet plate with teeth which is fixed to the top end shield. A carrier which is mounted on the motor coupling rotates along with the rotor. The carrier consists of locking members, either pins or balls that lock or engages against the ratchet teeth. The locking members move or slide in the holes/grooves present in the carrier. In the correct or desired direction of rotation and at lower speeds, the locking members slide or roll over the ratchet teeth. As the speed increases the locking members move into the carrier grooves/holes and allow the free spinning of the rotor. If the motor rotates in reverse direction and the speed drops below the engagement/drop speed, one of the members engages with the ratchet tooth and prevents the reverse rotation. Based on the locking member used, NRR mechanisms are available as pin-type NRR or ball-type NRR. Higher wear and tear, higher engagement speed and sparking are some of the drawbacks with pin-type NRR. The drawbacks of pin-type NRR make ball-type NRR a popular choice. The rapid engagement of locking members develops a huge amount of impact forces and shock. These impact forces and shock can damage and wear the ratchet, carrier, mounting hardware, etc. As the number of engagement/cycles increases, the wear also increases. The calculations of impact forces are very difficult which makes the design of NRR challenging. This paper outlays the design approach, calculation of engagement/drop speed, contact stress, estimation of impact forces using finite-element analysis, and testing methodology for ball-type NRR mechanism.

This paper reports a study on the influence of water contamination, in new and worked grease conditions, on five different commercially available wind turbine bearing greases. Among the studied greases were lithium and calcium-based soaps in combination with mineral and synthetic hydrocarbon oils of different viscosity and anti-wear additives. A series of tests using the Four Ball method for the evaluation of extreme-pressure properties of lubricating greases were performed in the samples, before and after being subjected to shear by Roll Stability test (i.e., worked condition) and water contamination, aimed to characterize the influence of these factors on the greases’ ability to reduce wear. The mechanical stability of the greases under the studied conditions was evaluated by monitoring the consistency change. The comparative analyses between the different greases made it possible to conclude, above all, that water contamination can have a great impact on a grease’s lubrication capacity, reducing from 17% to 32% its capacity to avoid wear. The changes in a grease’s properties can result in significant increase in bearing power losses and mechanical wear.

Companies aspire for leading position through competitive products that meet customer requests. Electrical rotating machines require, in addition to high efficiency, and continuously reduce noise levels to meet customer demands. The origin of the noise present in the motor needs to be known to work on reducing it and consequently increase the machine performance, making the product more reliable for each specific application. Bearing deterioration is the main factor that contribute to mechanical failures in electric motors. The evaluation of bearing behavior through noise and vibration analysis makes it possible to perform improvement studies and even machine intervention to increase its service life. Squeal noise is one of the noise types observed in bearings, characterized by its usually intermittent behavior and by apparent metal-to-metal sliding. A credible measurement system to quantify the desired measurand is a premise for any improvement work. Faced with the exposed, this paper contains the study of three different measurement systems to define which system can quantify the squeal noise in deep groove ball bearings used in induction electric motors. The systems studied are: sound pressure level, acceleration spectrum, and demodulation of acceleration spectrum. The present study evaluates these measurement systems through planned experiments, using the Six Sigma methodology by using Measurement System Analysis tool. These systems are analyzed for measurement stability, discrimination, repeatability, and reproducibility. An empirical noise evaluation is also performed. This enables a comparison between subjective values and results with the different measurement systems studied, helping to define which system best quantifies the squeal noise.

The traceable efficiency determinations with measurement uncertainty (MU) values for wind turbines on test benches or in the fields are very crucial and are of great interest for evaluating the usability of wind energy. In this paper, initially, different procedures for efficiency determination of the machine are compared and their electrical, as well as mechanical quantities are evaluated. Finally, the efficiency determination for rotating asynchronous electrical machine with a focus on MU values on an innovative small-scale test bench with results similar to nacelle test benches for wind turbines is presented.