Motor Insulation Research Articles

Optimum feature selection for classification of PD signals produced by multiple insulation defects in electric motors

Partial discharges (PD) are initiated in electrical equipment during various points of the equipment’s lifecycle. The intensity of PD defects rises continuously with time, which can lead to insulation degradation and reduced operational life of the electrical equipment. The optimum feature selection of PD signals captured, from different insulation defects, can enhance the classification accuracy of PD defects and facilitate better visualization of PD parameters for electric motor (EM) insulation monitoring and diagnostics. This paper presents a hybrid approach, based on Maximize Relevancy and Minimize Redundancy (mRMR) and random forest (RF), for the optimum feature selection and classification of PD signals in EMs containing multiple defects. For this purpose, four PD defects are developed in the EMs insulation under laboratory conditions, and 800 PD signals are acquired using a conventional IEC-60,270 experimental platform. The severity of these defects is determined and investigated based on PD characteristic parameters. Several features of both PD sweep signals and conventional PD pulses are extracted. Consequently, the mRMR feature selection technique is implemented to select the significant features of the detected PD signals. To establish the plausibility of this technique, several other feature selection algorithms, including RefliefF, Gini Index (GI), and Information Gain (IG), are introduced for the same datasets. The performance of all these feature selection algorithms is validated using three commonly used classification techniques such as RF, support vector machines (SVM), and k-nearest neighbors (k-NN). In summary, the results show that the combination of mRMR and RF proves to be the most effective feature selection algorithm for the classification of insulation defects in EMs, achieving an accuracy of 99.875%. This accuracy is significantly better than other feature selection and classification techniques and indicates its potential for application to other power system components.

Diversified Assessment of Ground-Wall Insulation in Inverter-Fed Motors by Using Transient Characteristics of Leakage Current

Diversified Assessment of Ground-Wall Insulation in Inverter-Fed Motors by Using Transient Characteristics of Leakage Current

A fabrication of universal multifunctional coating with excellent adhesion on the surface of solid rocket motor insulation materials through a surface activation strategy based on multiple interaction forces

In this work, a novel universal multifunctional coating for insulation materials was prepared by using polyethyleneimine as the coating substrate, low-temperature molten glass powders and MXene as additives. Meanwhile, the universal coating was tightly adhered to the surface of the insulation materials through a surface activation strategy based on the synergistic effects of hydrogen bonding, electrostatic adsorption, and chemical bonding. The shear strength data showed that the adhesion between the universal coating and the three types of insulation material were higher than that of most commercial adhesives. In the case of EPDM, for example, the adhesion of the coating is 4.17 (epoxy glue), 1.04 (chemlok) and 1.67 (Neoprene) times that of commercial adhesives, respectively. In addition, the universal coating showed good heat resistance and thermal insulation, and formed a complete and dense char on the surface after exposure to flame. The maximum mass loss temperatures of the three coated insulation materials were 2.8, 6.5, and 9.3°C higher than the original samples, respectively. Thermal insulation tests showed that the coated insulation materials reduced the average top surface temperature by 29.68%, 40.84% and 29.06%, respectively, compared to the original samples. The results of anti-migration tests showed that the prepared universal coatings displayed generally superior anti-migration properties to the insulation materials, with equilibrium migration concentrations reduced by up to more than 80% compared to the original samples, which is better than the previous products of the same type. In addition, the application potential of the advanced multifunctional insulation materials obtained from the preparation was evaluated, resulting in an increase of more than 35% in peel strength and more than 20% in shear strength for all insulation materials with propellants. This work provides a simple and environmentally friendly generalized strategy to develop high performance insulation materials for aerospace fields.

Age resistant low density peroxide cured EPDM rubber insulation for large rocket motors

AbstractNovel methodology introduced to incorporate peroxide in the rubber matrix led to successful development of peroxide cured EPDM insulation based on precipitated silica, a conventional filler. Effect of Silica Filler on the physical, mechanical, thermal, ablative properties and thermal degradation of such an insulation has been recently published. As an outcome of above study, peroxide cured EPDM insulation with 25 PHR of Silica, has been promulgated as potential low density insulation meeting all the requirements of Large Rocket Motor, while having a density as low as 0.997 g/cm3 and Tg as low as −55°C. Effect of aging on mechanical, thermal properties and thermal degradation behavior of low density peroxide cured EPDM insulation has been studied and the findings have been corroborated by FTIR Spectroscopy and morphological Examination by SEM.

Fillet Radius Impact of Rectangular Insulated Wires on PDIV for Turn-to-Turn Insulation of Inverter-Fed Motors

Fillet Radius Impact of Rectangular Insulated Wires on PDIV for Turn-to-Turn Insulation of Inverter-Fed Motors

Исследование существующих методов сушки увлажненной изоляции тяговых электродвигателей локомотива

Objective: consider the issue of increasing the reliability of electric locomotive traction motors, which depends on various factors. This article examines the factor of the impact of climate conditions on the operation of a locomotive. All attention is paid to the relevance of research into methods for drying the insulation of traction motors at the present time. It has been proven over many years of work that the most vulnerable part of the engine is insulation. All methods that are aimed at solving the assigned problems are listed. The article describes the principle of operation and technology of processes in each of these methods. From the proposed methods, efficiency indicators are derived from the perspective of technical and economic results, and some of their advantages and disadvantages are also noted. The article is based on a comparison of various methods that are aimed at solving current problems associated with increasing the reliability of traction rolling stock. Statistics on traction motor failures over the past three years are presented, and the reasons for moisture in the insulation of electric locomotive power equipment are described. The main methods and methods for drying moistened insulation used in VSZhD locomotive depots are listed, and the characteristics of each method are given. Methods: the method of statistical data and analytical review of the current state of the process of drying the insulation of traction rolling stock was applied. Results: the article lists the studies, experiments and results that evaluate the existing methods and methods of insulation drying processes on rolling stock. An updated method of three-cycle drying of moistened insulation of electrical machines has been developed, which is based on the use of electric heating units and provides for oscillatory energy supply. The task has been set to solve the optimal methods for removing moisture from the insulation of traction motors of electric locomotives based on the use of the convective method. Practical importance: based on the conducted research, the possibility of using the proposed three-cycle method for drying moistened insulation of electrical machines has been confirmed, which allows reducing energy costs for repairs and the time of the insulation drying process.

Insulation life prediction of stacking multi-model fusion motors based on Conv1d-LSTM

Abstract The insulation system of the mine motor is key to ensuring its stable operation, which affects the efficiency of mine production and transportation and the benefit of enterprises. The prediction of motor insulation life can effectively prevent the deterioration of motor performance. Due to the complex underground environment, many factors affect the insulation of coal mine motors, which are not conducive to the selection of feature parameters. The insulation life prediction efficiency and accuracy of motors need to be improved. To solve this problem, this paper proposes a prediction method based on Conv1d (one-dimensional convolve) and LSTM (long short-term memory neural network), which integrates multiple models and the Stacking integrated algorithms. The operating data and environmental parameters of a coal mine motor under different conditions are analyzed. Three Conv1d-LSTM hybrid models with batch normalization, residual network, and dense number are used as the base learner, and the results are weighted by K-fold to verify the accuracy of the three models. The linear regression model is used as a meta-learner to prevent overfitting of the model and effectively improve the speed and accuracy of single network optimization. Compared with the traditional method, the results show that the optimization of the LSTM neural network by the multi-feature model has a higher accuracy in predicting the remaining life of motor insulation, which provides a new way for the prediction of motor insulation life.

Preparation of ablation-resistant ethylene propylene trioxide/polyimide staple fiber composite insulation layer by solution wet mixing process

This research developed a solution wet mixing process for creating Ethylene propylene diene monomer/polyimide staple fiber composites (EPDM/PISF), overcoming the uneven fiber distribution seen in traditional dry mixing techniques. By uniformly dispersing PISF within the EPDM matrix, the wet mixing process improves the composite's performance. This is evidenced by an 18.08 % reduction in ΔG′, a 14.29 % lower linear ablation rate (0.042 mm/s), enhanced thermal stability, a higher charring rate, and a denser carbonized layer. Optimal overall performance was achieved using a PISF content of 10phr in the wet mixing process. This advancement significantly enhances the ablation resistance of EPDM/PIS, making them a promising choice for high-performance and durable insulation in solid rocket motors.

Modeling Humidity Impact on PDIV for Turn-to-Turn Insulation of Inverter-Fed Motors at Different Temperatures

Modeling Humidity Impact on PDIV for Turn-to-Turn Insulation of Inverter-Fed Motors at Different Temperatures

Обеспечение безопасности труда горнорабочих совершенствованием электрических сетей при подземной добыче руд

In recent years, more attention has been paid to the increase in energy consumption by mining enterprises operating mines due to the need to replace the installed electric equipment and implement automated process management systems in mining and transport areas of the mine, which ultimately ensures safe and faultless operation of power supply system at various voltage levels in both individual subdivisions and the entire mine. During the experimental studies and solving problems, safe conditions for maintaining electric installations of the mine and maintenance personnel will be ensured. Weaknesses of the grid insulation and its elements have been detected; stable values for the resistance of motor insulation, switching equipment, laid cables, and the relevant probability distribution densities have been provided. This enables the replacement of individual unstable sectors of the power grid with new cables and equipment, which will significantly improve the safety of mining operations in the conditions of a high-altitude mine. It has been established that the motors used as actuators for scraper winches and fans must be replaced with motors of similar power equipped with organosilicon insulation or filling of frontal parts with enamel paint. The conducted studies enable the development of a comprehensive inspection methodology of the mine power supply system’s insulation elements and its application for further studies at other mines.

Temperature Impact on PDIV for Turn-to-Turn Insulation of Inverter-Fed Motors: From Ground Level to Cruising Altitude

Temperature Impact on PDIV for Turn-to-Turn Insulation of Inverter-Fed Motors: From Ground Level to Cruising Altitude

A high efficient 33 level inverter for electric vehicle application using PMSM

The permanent magnet synchronous motor (PMSM) avoids commutation-related torque ripples and produces smooth torque. Its great handling capacity and better efficiency make it an excellent choice for high-demand applications. A typical PM motor drive fed with pulse width-modulated voltages may cause the motor insulation to break down if rapid voltages (dv/dt) occur across the motor terminals. Applying variable voltage with low dv/dt and implementing multiple inverter topology can solve this issue. Multilevel converters have minimal switching losses, better power quality and the ability to operate at both fundamental and higher switching frequencies. In this study, a three phase stacked multilevel inverter-based FOC driven PMSM drive design is proposed. Here, the neutral point is a capacitor intermediate point on DC side, where current is naturally balanced throughout a switching cycle. This makes it possible to use downstream batteries and even lower voltage equipment, greatly increasing efficiency, improved performance and smother control at low speed. Therefore, direct-battery-driven electric vehicles will be able to use this. A 33 level inverter-based PMSM drive was used to implement the FOC, and the simulation results were used to validate it. The Matlab/Simulink tool is used to simulate the entire system.

PDIV Modeling for Rectangular Wire Turn-to-Turn Insulation of Inverter Fed Motors Through Thermal Aging

PDIV Modeling for Rectangular Wire Turn-to-Turn Insulation of Inverter Fed Motors Through Thermal Aging

Air Pressure Impact on the Avalanche Size for Turn-to-Turn Insulation of Inverter-Fed Motors

Air Pressure Impact on the Avalanche Size for Turn-to-Turn Insulation of Inverter-Fed Motors

Термические напряжения в изоляции тяговых электродвигателей локомотивов

Thermomechanical processes and cyclic temperature changes in the structure of insulation of traction electric motors lead to thermal gradient appearance. Increased temperature widens the elements of winding, damages insulation material (thermal fatigue, extreme deformation, creeping, etc.). Methods for the numerical study of stress-strain state of the material of the insulation of traction electric motors of diesel locomotives on different stages of static and cyclic loading have been developed. It is determined, that the main factor defining the intensiveness of insulation aging is the impact of alternating cyclic thermo-mechanical stresses, but not thermomechanical destruction of impregnating composition. Analytical expressions for the evaluation of stress-strain state of insulation of traction motor diesel locomotives are received and they are distinguished by the fact that they require a relatively small amount of basic data and let conduct accurate calculations taking into account the peculiarities of the electric drive system. An approximate predictive model for the evaluation of interphase thermal stresses in the assembly of the materials of winding slots of the traction electric motor of a diesel locomotive is developed. The insulation material is considered as linear elastic when the deformation level is less than the yield strength. The joining components can be considered from the view point of structural analyses as elongated rectangular plates suffering from linear elastic strains. The analyses results can be used for evaluation of thermomechanical stresses in the impregnating materials of traction electric motors of diesel locomotives and their analogues.

Nano-hydroxyapatite filled EPDM nanocomposite: towards green elastomeric thermal insulating coating with superior mechanical, thermal, and ablation properties

ABSTRACT Heat-shielding composite materials containing asbestos has been used for thermal insulation of aerospace rocket motors. However, asbestos has carcinogenic effects on both human and environment. This study was directed to the development of novel elastomeric nanocomposite thermal-shielding coating (asbestos-free); the developed elastomeric nanocomposite was based on hydroxyapatite (HA) nanoparticles (NPs) in an ethylene propylene diene monomer (EPDM) matrix. HA is a bio-ceramic material with 18.5 wt % phosphorus; HA can act as nano phosphorus-based fire extinguisher. HA NPs were synthesized by continuous hydrothermal technique; high crystalline HA nanoplates of 350 nm length, and 100 nm width were successfully developed. HA NPs were integrated into EPDM matrix; uniform dispersion of HA particles was verified via EDAX analysis. The impact of HA NPs on EPDM tensile strength, elongation-at-break, hardness, density, thermogravimetric analysis (TGA), thermal conductivity test, and ablation test was assessed to asbestos fibers. HA/EPDM secured superior mechanical properties compared with Asbestos/EPDM; HA NPs secured an increase the tensile strength, elongation at break by 16.2% and 105.3% respectively. HA with surface hydroxyl groups could be integrated into EPDM matrix via chemical bonding. HA offered novel thermal shielding properties; HA secured a decrease in thermal conductivity coefficient by −21.1%; and the best ablation resistance was increased by + 31.5%. Residual weight was increased by 13%, compared with asbestos fibers.

Study on flame retardancy of EPDM reinforced by ammonium polyphosphate.

Currently, the most widely used material for solid rocket motor (SRM) insulation is ethylene propylene diene monomer (EPDM) filled with flame-retardant and ablation-resistant fillers. Researchers have been working hard to find a flame-retardant filler that can simultaneously meet the complex requirements of mechanical strength, density, flame retardancy and ablative performance of the insulation layer. This requires research on the flame retardant properties of flame retardants in oxygen-poor environments. In this paper, ammonium polyphosphate (APP) is used as a flame retardant filler, which is filled into an EPDM premix (p-EPDM) containing fumed silica and aluminum hydroxide to prepare composite materials. By creating an anoxic environment, the flame retardant behavior of APP under anoxic conditions on EPDM was studied. The results show that composites prepared with APP show better flame retardant properties in tests such as limiting oxygen index and UL-94, with less impact on mechanical strength and density. The surface morphology and elemental composition of the composite combustion residues were studied using Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). In an oxygen-depleted environment, APP will thermally decompose to form ammonia, water vapor and phosphorus-containing acidic substances. These gases dilute the flammable gas and reduce the thermal conductivity. The acidic substances containing phosphorus are concentrated on the surface of the pyrolysis layer to promote the formation of the carbon layer. This provides guidance for us to design insulation layer materials with properties that are more in line with actual use requirements.

SiC-MOSFET-Based High Voltage Pulse Generator for Testing Motor Insulation Used in EVs

SiC-MOSFET-Based High Voltage Pulse Generator for Testing Motor Insulation Used in EVs

Correction to Impact of air pressure variations on electrical vehicle motor insulation

Correction to Impact of air pressure variations on electrical vehicle motor insulation

Bench tests of noise-insulating materials

A group of employees of the Scientific, Educational and Production Laboratory "Outboard Boat Motors" of the Department of Water Transport Operation of the Federal State Budgetary Educational Institution "AGTU" achieved certain results in the fight against noise, reflected in a number of patents of noise-insulating hoods of various modifications and publications on the analysis of the frequency spectrum of outboard boat motor noise, evaluation of the effectiveness of outboard motor hoods of small-sized Based on the accumulated scientific research, several proto-types of multilayer means recommended for sound insulation of outboard boat motors have been created. In the conditions of a large range of directions, there is a need to apply single-layer or multi-layer structures to the properties of sound insulation without forming a physical model of the hood, casing. This is due to the fact that the production of a hood model entails a complex technological process, while creating a sample in the form of a plate from the same material is much more profitable in terms of financial, labor and time costs. Based on the needs of the scientific educational and production laboratory of outboard boat motors in the study of noise generated by outboard boat motors and means of combating them, it was decided to create a stand to assess the effectiveness of noise-reducing materials, which will allow modeling the conditions of natural operation of a noise-insulating material without the use of full-scale tests with outboard by motor. The created stand allows testing in two directions. The first direction is the testing of physical models of casings for noise insulation using audio files reproducing the noise of the required equipment. The second direction is the study of materials for their noise-insulating properties when generating waves of different frequencies.