Data to support the assessment of the energy efficiency estimation methods on induction motors considering real-time monitoring. (original) (raw)
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Measurement, 2019
Different methods have been developed to estimate the energy efficiency of induction motors. The accuracy of these methods vary with the load factor, the unbalanced voltage (UV) and harmonics. The feasibility of these methods for efficiency estimation in real-time were theoretically and experimentally assessed during the operation under different operational conditions (i.e. balanced sinusoidal voltage (BSV), harmonics, UV and harmonics with UV). Results show that for load factors over 80%, the air-gap method is applicable under any condition, while the slip method is only applicable under BSV or balanced harmonic voltage. Moreover, for load factors over 40%, the nameplate method is applicable under BSV. Other methods result in errors over 8% and optimization methods are not applicable for real-time monitoring. Electric systems generally operates with some degree of UV and harmonics, while induction motors mostly operate with load factors below 60%, limiting the use of these methods for real-time measurement.
Non-invasive monitoring system for analysis of energy efficiency of three-phase induction motors
2022
In the Three-Phase Induction Motor (3phase IM), as in any electromechanical energy converter, the electrical input power (required from the power supply) is equal to the mechanical output power delivered to the load plus the losses inherent to the process. Even though they are intrinsically efficient devices, 3-phase IM constitute a great potential for energy conservation when energy efficiency actions are carried out in an industry. This article presents an accessible monitoring system for the various industrial segments, justifying the development of a monitoring system using low-cost, non-invasive, cloud, robust technologies that allow a simple and remote visualization of the percentage loading, which is an indicator of the efficiency of electrical machines. In this way, the characteristics of this system make it possible to use it on a large scale, that is, in the large number of motors installed in the industry, enabling the diagnosis of possible applications that require adjustments to the actuators. With the experimental results, the functionality of the developed monitoring system was verified with a percentage error of up to ±10% between percentage of the nominal loading from 82% to 110%. Keywords-Three-phase electric motors, Noninvasive load analysis energy efficiency, IoT.
Economic Efficiency Measure of Induction Motors for Industrial Applications
International Journal of Electrical and Computer Engineering (IJECE), 2017
This paper, introduced an expression of Economic Efficiency Measure (EEM) to permit quick evaluation for replacement of faulty induction motor with alternative (new or refurbished motor) for lowest life-cycle cost based on efficiency and rated-load conditions. This approach, simplifies the process for evaluating the energy efficiency to mere proportionate factor called as EEM. During the operating phase, the motor losses correspond to extra energy consumption, based on various parameters like motor operating conditions, operating hours, operating costs, fault factor, depreciation factor and fixed costs. The approach is effective in addressing the global issue on replacement of the faulty motor that needs a comprehensive analysis and mathematical expression. Compared to other alternatives the EEM provides a simple but effective and reliable means to asses, the feasibility of replacing or refurbishing the faulty motor. A detail analysis here would establish how much the present approach is effective in determining the replacement for a faulty induction motor either by a new one or refurbished one of corresponding rating. 1. INTRODUCTION The induction motor is the main driven system in industries, which consumes 30-60 percent of total electrical energy. Energy is utmost need in every field to perform activities whether it is residential, commercial, industrial, agricultural and host of alike applications. The need for energy conservation is vital but the best practice principle while selecting induction motor begins with analyzing the life cycle cost of the motor. Life cycle cost is a financial principle for selection of motors as they consume more than half the energy used by the plant [1]. In general, 65 percent of the total load is industrial load in India and 90 percent of this industrial load is induction motor load. It is a well known fact that induction motor operating at full load offers good efficiency, even at relatively modest kW-rating. However, at lower values than rated loads, which is common condition that many motor experience for significant portion of their service, their efficiencies decreases and increases losses so energy consumption is more in industry [2]. The efficiency of a motor is determined by intrinsic losses (fixed losses and variable loss) that can be reduced only by changing the design of the motor. It is evident that optimizing efficiency of induction motors would significantly address this issue but major task lays mostly in its difficult controllability, due to its complex mathematical model, its non linear behavior during saturation effect and the electrical parameter oscillation which depends on the physical influence of the temperature. When induction motors are operated without a proper control (drive), the motors are consuming large energy and the operating costs are high. These physical and operational disturbances often cause failure of the motor, often replacement of the motor is considered as a viable solution but often to reinstall a failed motor after refurbishing could be economically feasible. The most common cause of
IEEE Industry Applications Magazine, 2000
COMPARISON OF THE DIRECT AND indirect measurements of induction machine efficiency from a collection of test data is presented in this article. The efficiency is computed from 1,000 induction motors rated 1-250 hp to show the relative accuracy of the methods. The Bland-Altman procedure for comparing measurement methods is used in the analysis. Motor Efficiency Induction motor efficiency can be determined as a ratio of the measured output power to the input power. The efficiency computed directly from this ratio is known as the direct efficiency. Alternatively, the efficiency can be calculated by determining and summing up all the losses in the motor and using the input power to calculate the efficiency. This method is known in standards as the input-output method with loss segregation. It is an indirect measurement that is considered to be more accurate if the stray load loss (SLL) is accurately determined. However, the indirect
A survey of efficiency-estimation methods for in-service induction motors
IEEE Transactions on Industry Applications, 2006
Condition monitoring of electric motors avoids severe economical losses resulting from unexpected motor failures and greatly improves the system reliability and maintainability. Efficiency estimation, which shares many common requirements with condition monitoring in terms of data collections, is expected to be implemented in an integrated product. This brings more considerations into the selection of the efficiency-estimation methods. This paper presents the results of an up-to-date literature survey on efficiency-estimation methods of in-service motors, particularly with considerations of the motor-condition-monitoring requirements. More than 20 of the most commonly used methods are briefly described and classified into nine categories according to their physical properties. Six categories of these methods are more related to in-service testing and are compared in a table summarizing the required tests and measurements, intrusion level, and average accuracy. Estimation of the rotor speed and the stator resistance, the two stumbling blocks of various efficiencyestimation methods, is also carefully studied; commonly used methods are summarized. Based on the survey results, four efficiency-estimation methods are suggested as candidates for nonintrusive in-service motor-efficiency estimation and conditionmonitoring applications. Another contribution of this paper is that a general approach for developing nonintrusive motorefficiency-estimation methods is proposed, incorporating rotor speed, stator resistance, and no-load loss estimations.
Energy Management by Online Efficiency Estimation and Condition Monitoring of Induction Motor
Induction motors are the most commonly used machine in industry because of their robust nature. Energy management of induction motor is relevant as they form the bulk segment in industry. So online monitoring and efficiency estimation of the existing induction motors play a vital role in energy management. The air gap torque (AGT) method is a well established technique for determining the efficiency of an induction motor, since it is known to be highly accurate. However, it is considered to be too intrusive for industrial applications. To resolve this, non-intrusive AGT (NAGT) method is adopted here for efficiency estimation. The NAGT method measures only the motor terminal quantities and combines various estimation techniques to determine these parameters in a non-intrusive manner. Speed is measured by using tachometer. Stator resistance is obtained by DC signal injection method. No load losses are assumed empirically as a percentage of rated input power. Stray loss is estimated by...
Variable Frequency Drive Source Based Efficiency Measurement of an Induction Motor
International Journal of Innovative Technology and Exploring Engineering (IJITEE), 2020
Induction motor loss separation and efficiency measurement needs loading dynamometers and other tools as like variable voltage sinusoidal power supply. These are costly and not always usable except though a loading tool is usable. Variable frequency drives are also commonly utilized for running induction machinery and are readily accessible and low cost. Nevertheless, their usage in lieu of a constant frequency sinusoidal power supply to calculate system performance precisely is interesting, but potentially difficult because of the PWM output voltage. This paper provides few studies into the usage of variable frequency drives. The usage of the machine, the measurement criterion and the protocols shall be reported and addressed. The output presented describes the possibility of the suggested idea of calculating machine effectiveness with a PWM power source.
Standard Efficiency Determination of Induction Motors With a PWM Inverter Source
IEEE Transactions on Industry Applications, 2019
Induction motor loss segregation and efficiency measurement requires loading dynamometers and other equipment such as a variable voltage sinusoidal power supply. These are expensive and not often available even when a loading device is accessible. Variable frequency drives are now widely used for operating induction machines and are more widely available and less expensive. However, their use in place of a fixed frequency sinusoidal power supply to directly measure machine efficiency is intriguing, but inherently challenging due to the PWM output voltage. This paper presents some investigations for using variable frequency drives to perform IEEE 112B and IEC 60034-2-1 tests. The use of the drive, the measurement criteria and procedures are reported and discussed. The results presented demonstrate the feasibility of the proposed concept for measuring machine efficiency with a PWM power source.
Comparison of induction motor field efficiency evaluation methods
IEEE Transactions on Industry Applications, 1998
Unlike testing motor efficiency in a laboratory, certain methods given in IEEE Standard 112 cannot be used for motor efficiency evaluations in the field. For example, it is difficult to load a motor in the field with a dynamometer when the motor is already coupled to driven equipment. The motor efficiency field evaluation faces a different environment from that for which IEEE Standard 112 is chiefly written. A field evaluation method consists of one or several basic methods. This paper separates and compares the basic methods according to their physical natures. Their intrusivenesses and accuracies are also discussed. This paper is useful for field engineers to select or to establish a proper efficiency evaluation method by understanding the theories and error sources of the methods. ).