The condition of electromagnetic relays is crucial to the safe and normal operation of the high-speed train (HST). At present, there are no proper testing and assessment methods for the condition of electromagnetic relays. Electromagnetic relays experience aging and failure over their service time, which causes many potential security problems. To solve these problems, the failure mechanisms of electromagnetic relays are analyzed. The Fick diffusion theory and the Larson–Miller method are used to deduce the degradation models for contact resistance and closing time. Based on these models, an approach to calculate relay life is proposed. To verify the effectiveness of the proposed method, a test platform was designed and built. The accelerated life test was carried out by using Siemens 3TH electromagnetic relays (3TH4244-OLF4, Siemens, Suzhou, China). Contact resistance and closing time were measured using a test platform. The least squares fitting was used to calculate the residual sum of squares and the unknown parameters in the degradation models with the test data. The optimal degradation model was chosen according to the fitting results. Relay life at four temperature stress levels was predicted by the optimal degradation model and failure threshold of the relays. The result indicates that the life of the electromagnetic relays at ambient temperature is 11,874 days and prediction error is about 5%, which provides important guidance for the maintenance of electromagnetic relays.

A Reliability Assessment Method for High Speed Train Electromagnetic Relays

For advanced attitude control of the satellite, reaction wheels are used, which are actuated by motor. Fault detection and prediction of Remaining Useful Life (RUL) of the motor is of great importance. This study aims to demonstrate health management of reaction wheel motor in satellites by estimating the RUL of the damping coefficient. Multi-scale Extended Kalman Filter (EKF) is employed for this purpose using the data of input current and output velocity measured during the life test of the motor. The motor dynamic behavior is modeled by the ordinary differential equations. The damping coefficient is taken as the health indicator, which is obtained by solving the micro EKF problem. To set threshold for the damping coefficient, degradation behavior of characteristic curve that evaluates the motor performance is used to correlate with the degradation of the damping coefficient. Then, the RUL is predicted by solving the macro EKF problem.

/pdf/remaining-useful-life-prediction-of-reaction-wheel-motor-in-nc0dt1n9z4.pdf

Remaining useful life prediction of reaction wheel motor in satellites

A design gauge pressure of an eco-friendly gas insulated switchgear (GIS) with an application of vacuum interrupters (VIs) ranges from 0.1 to 0.3MPa. Therefore, a high differential pressure is imposed on bellows of the VIs, which increases the fatigue failure risk of the bellows after cycles of operations. Although, there are some empirical equations recommended by the Chinese National Standard GB/T 12777-2008 which can be used to evaluate the fatigue life of the bellows, there still remains little understanding on the fatigue life of the bellows when the VI is subjected to a high differential pressure and a high operating velocity. The objective of this paper is to determine the relationship between the fatigue life of bellows and high differential pressure and high operating velocity. A fluid-structure interaction simulation is set up to analyze the equivalent stress and the fatigue life of VI bellows under differential gauge pressure ranging from 0.1MPa to 0.3MPa, and under differential operating velocity ranging from 2m/s to 4m/s. The simulation result shows that with an increasing of the pressure and operating velocity, the equivalent stress increases and the fatigue life decreases from 47957 cycles under 0.1MPa and 2m/s to 489 cycles under 0.3MPa and 4m/s. At last, a comparison between the simulation result and the empirical equations shows a limitation of the empirical equations, in which there is lacking of the operating velocity.

Fatigue life simulation of vacuum interrupter bellows subjected to high gas pressure and high operating velocity

Electric motors, converting electrical energy into mechanical energy, are widely utilized as the primary power source for electromechanical equipment. However, the huge energy consumption of electric motors makes their energy efficiency improvements crucial for achieving greenhouse gas reduction goals. As a result, low-efficiency asynchronous motors are being eliminated, while their high-value recycling has subsequently become a key issue. Remanufacturing offers a promising solution to upgrade low-energy efficiency asynchronous motors to high-energy efficiency permanent magnet synchronous motors, but its environmental benefits are unclear. A novel dynamic assessment model that integrates life cycle assessment and lifetime distribution modeling to evaluate the environmental benefits of motor remanufacturing is established. A manufacturing and four remanufacturing scenarios based on the damage profile of individual motor components are developed. The results demonstrate that motor remanufacturing can significantly reduce carbon emissions by 26.75%–65.13%. The model was also applied to various recycling scenarios and synchronous motor market penetration levels to provide a long-term environmental benefit in the motor industry in China by 2040. Findings suggest that the motor remanufacturing industry can achieve peak carbon reduction in 2035 and 2033 under the medium and high market penetration scenarios, respectively. It's also disclosed that remanufacturing offers considerable material savings (36%–73%), energy savings (28%–63%), and water savings (34%–88%). The environmental benefits of motor remanufacturing industry are quantified for the first time, demonstrating its effectiveness in facilitating a green and low-carbon transition. The dynamic assessment methodology system constructed in this research can provide a theoretical framework and research ideas for the environmental impact assessment of other end-of-life product management. 

Dynamic simulation of life cycle environmental benefits of remanufacturing asynchronous motors to permanent magnet synchronous motors

Performance Degradation Model and Reliability Evaluation of Brush DC Motor for the Intelligent on–Off Valve

On the ground of high resistance to pressure, long life and good retractility, the welded metal bellows are widely used by the space industry. Their performance reductions have a serious effect on the system reliability of space products during the storage. The strength and stiffness analysis of welded metal bellows are performed by theoretical research, numerical simulation and test verification in this paper. Moreover, it is ascertained that the main failure mode of bellows is stress looseness. Then the residual load carrying capacity is confirmed as the failure criterion of bellows. The variation of residual load carrying capacity with time is derived on the base of Larson-Miller model. Then, the assessment model of bellows storage durability is based on stress-strength model. At last, some welded metal bellows storage test data are evaluated through this method, and life evaluation on storage durability of bellows is presented. This method is great guidance significance for optimizing the design of welded metal bellows assembly and assessing storage reliability of space products.

Storage durability life and reliability analysis of welded metal bellows

Induction motors are widely used in industry, and usually have a long life. To predict the life and reliability of the motors within a reasonable time, a simple and available accelerated degradation testing method is presented. To simulate the unbalanced load on the motor, the lamina with circular holes is mounted on the shaft of the motor eccentrically, and different unbalanced loads are obtained by changing the mounted places of the lamina. A motor accelerated test with three kinds of stress is applied, and the Orbit Areas are used to reveal the performance degradation index of motor. The life and reliability of the motor is finally predicted and evaluated with a balanced lamina mounted on the shaft as its normal working condition. The accelerated degradation testing approach has been proven to be practical to predict the life of the motors.

Study on the life prediction of induction motors based on accelerated degradation testing method

For complex system with Long-term storage, only a few storage information can be obtained, usually including the data of periodical curtailed inspection and some routine test data. It is very difficult to assess the storage life and reliability of complex system under this condition. In order to resolve the practical engineering problem, a storage information acquisition method is proposed by combining accelerated storage test with qualification test on ground. By this method the typical single machine and simple system storage information were acquired. All kinds of typical equipment storage information and nonmetal material, which include accelerated storage test information, qualification test information on ground, on-site storage information, storage environment data and routine test information, are fused into the new storage information database. On the foundation, storage life and reliability assessment method for complex system is developed based on the field storage information and accelerated test information fusion analysis. And then, the storage reliability of the stored complex system storing for several years is given by that assessment method.

Study on storage reliability assessment method of complex system based on life distribution

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Storage durability life and reliability analysis of welded metal bellows

Study on the life prediction of induction motors based on accelerated degradation testing method

Study on storage reliability assessment method of complex system based on life distribution