A locomotive contactor residual life research method

Abstract

A locomotive contactor residual life research method, comprising: determining multiple types of characteristic parameters through failure mechanism analysis; collecting actual operation data and establishing a database; evaluating parameter health range by using Box-whisker plot analysis method and screening key parameters; verifying the health model through life test; and establishing a residual life evaluation model based on the threshold of the characteristic parameters. The present application realizes accurate and scientific prediction of the life of the contactor by combining real operation data with failure mechanism, and is suitable for state maintenance and life management of the electric locomotive contactor.

Description

Technical Field

[0001] This invention relates to the field of electrical component life prediction technology, and in particular to a method for studying the remaining life of locomotive contactors based on actual condition detection data. Background Technology

[0002] As a crucial electronic component in electric locomotives, the reliability of contactors directly impacts the operational safety of the entire vehicle. Currently, contactor maintenance primarily employs a scheduled maintenance model, which may result in either over-maintenance or under-maintenance, making it neither economical nor environmentally friendly. Furthermore, existing life prediction methods are mostly based on accelerated life tests in laboratories, which differ significantly from real-world operating conditions, leading to insufficient prediction accuracy.

[0003] Existing technologies, such as patent CN201710491938.1, predict lifespan using only current parameters, which is a single parameter; while patent CN202210149504.4 introduces multiple characteristic quantities, it lacks a comprehensive analysis of the actual operating environment and fails to fully combine and utilize data, fault data, and failure mechanisms, resulting in large errors in the model in practical applications.

[0004] Therefore, there is an urgent need to propose a contactor remaining life assessment method that is closer to actual operating conditions, has comprehensive parameters, and provides scientific analysis. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for studying the remaining life of locomotive contactors. By collecting and analyzing contactor status data in actual operation, and combining failure mechanism and health status assessment, a life prediction model based on multiple characteristic parameters is established to assess the remaining life of the contactor and provide data reference for locomotive component maintenance.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for studying the remaining life of locomotive contactors, comprising the following steps: (1) Failure mechanism analysis: Combining the stress environment, product structural characteristics, historical operation data, maintenance data and fault data of the contactor, identify the key life risk points of the contactor and their corresponding sensitive stresses, and determine the characteristic parameters to be collected, including: overtravel distance, opening distance, pull-in holding current, contact resistance, pull-in voltage, release voltage, pull-in time, release time, pull-in synchronization time, and release synchronization time. (2) Feature parameter extraction: Collect the above feature parameters of new products and actual operating contactors with different service years, record the service years, installation location and load information of each sample, and establish a contactor feature parameter database under real working conditions; (3) Status data analysis: The collected data is cleaned and classified, grouped by product model and load circuit consistency, and sorted by service life. The changing trend of each characteristic parameter with the service time is observed. (4) Health status assessment: The stability and dispersion of the characteristic parameters in each dataset are assessed by using the Box-whisker plot analysis method. The boundary of outliers is adjusted in combination with the actual physical meaning to determine the health range of each characteristic parameter and to screen out the key characteristic parameters that have a significant impact on the performance of the contactor. (5) Life test verification: Based on the actual service life and usage frequency of the contactor, estimate the number of operations required to reach the next overhaul, and reserve a margin, and set the number of life tests; samples are drawn from outside and outside the health range to conduct life tests to verify the effectiveness of the health range assessment model. (6) Establishment of remaining life assessment model: Based on the health threshold of key characteristic parameters and their correlation with life, a contactor remaining life assessment model is constructed to predict whether the contactor can operate safely until the next maintenance cycle.

[0007] As an improvement, the method is used to study the remaining life of contactors during the C6 overhaul stage of HXD1 series electric locomotives.

[0008] As an improvement, in the health status assessment step, key characteristic parameters include overtravel distance, opening distance, pull-in sustaining current, and contact resistance.

[0009] As an improvement, in the life test verification step, the test termination condition is the completion of a predetermined number of actions or the contactor failing to close / open normally.

[0010] The beneficial effects of this invention compared to the prior art are: 1. Closely reflects actual working conditions: Analysis based on real operating data improves the accuracy and practicality of life prediction; 2. Comprehensive and scientific parameters: By integrating multiple characteristic parameters and combining them with failure mechanisms, the evaluation is more comprehensive; 3. Economic and environmental benefits: Implement condition-based maintenance to avoid over-maintenance and under-maintenance, thereby reducing total life-cycle costs; 4. Enhance safety: Promptly detect aging components, prevent malfunctions, and ensure safe locomotive operation. Attached Figure Description

[0011] Figure 1 This is a flowchart of the present invention.

[0012] Figure 2 This is a schematic diagram of the contactor structure.

[0013] Figure 3Example diagram showing the distribution of characteristic parameter detection results for auxiliary frequency converter and voltage converter circuit contactors.

[0014] Figure 4 Box-whisher plot of pull-in sustaining current parameters.

[0015] Figure 5 Box-whisher plot for release time.

[0016] Figure 6 Box-whisher plot for releasing voltage. Detailed Implementation

[0017] The present invention will now be further described with reference to the accompanying drawings.

[0018] A method for studying the remaining life of locomotive contactors is illustrated in this embodiment, using the auxiliary frequency converter and voltage transformer circuit contactor during the C6 overhaul stage of the HXD1 series electric locomotive as an example. Figure 1 As shown, it includes the following steps:

[0019] Failure mechanism analysis: such as Figure 2 As shown, the auxiliary frequency converter and voltage transformer circuit contactor includes a contact spring 1, a moving contact 2, a stationary contact 3, a bracket 4, a return spring 5, a moving iron core 6, a stationary iron core 7, and a coil 8. The main contacts are normally open. After the coil is energized through the control port, the electromagnetic force pulls the main contact linkage, causing the moving and stationary contacts of the main contacts to connect and form a closed circuit. At the same time, the linkage drives the auxiliary contacts, causing them to provide a closing feedback signal. When the auxiliary converter starts working, the auxiliary system output contactor closes. When the auxiliary converter is disconnected or other abnormal conditions occur, the auxiliary system output contactor needs to be actively disconnected while energized. Large currents flow during both opening and closing processes. Simultaneously, as the number of contactor operations increases, the spring return force tends to degrade. Electrical wear of the main contacts and reduction in spring return force are the main factors affecting the lifespan of this contactor. The combined effect of electrical wear of the main contacts and reduction in spring return force manifests as a reduction in the contactor's overtravel distance, while contact wear manifests as an increase in the contactor's opening distance. Contact surface contamination and reduced contact area together result in increased contact resistance. Changes in coil resistance, increased mechanical resistance, or increased core gaps lead to changes in the pull-in and holding current. By collecting historical operational, maintenance, and fault data, it was found that the contactor experienced faults at different times due to reduced spring reaction force, increased contact resistance leading to three-phase imbalance, and significantly increased coil resistance. This verifies that the characteristic parameters representing the failure mechanisms described above are important parameters. Ultimately, the following characteristic parameters were selected for collection: overtravel distance, opening distance, pull-in and holding current, contact resistance, pull-in voltage, release voltage, pull-in time, release time, pull-in synchronization time, and release synchronization time.

[0020] Feature parameter extraction: Samples of contactor C6 of this model used in this circuit were collected, totaling 75 samples from 3 different application areas. Feature parameter testing was performed, and the actual service life of each sample was recorded during the testing, as shown in Table 1. The production year 1328 represents the 28th week of 2013. New product data was also collected in the same manner.

[0021] Table 1. Example of test results for C6 auxiliary frequency converter / voltage transformer circuit contactor during overhaul.

[0022] Status data analysis: The collected sample data (including new products) is cleaned, sorted by production year from earliest to latest, and a scatter plot of the detection results for each characteristic parameter is drawn to observe the changing trends of each characteristic parameter. For example... Figure 2 As shown, the pull-in holding current is mainly concentrated in the range of 170–180 mA, the pull-in time is concentrated in the range of 4–6 ms, the overtravel distance is concentrated in the range of 1–2 mm, and the contact resistance is concentrated in the range of 0–10 mΩ. Analysis of the condition data of the repaired samples for each characteristic parameter revealed that, except for a few samples whose test results deviated from the concentrated range, there was no obvious degradation trend overall.

[0023] Health status assessment: such as Figures 4 to 6 As shown, the Box-whisker plot analysis method was used to evaluate the stability and dispersion of each characteristic parameter in each dataset. Taking pull-in holding current, release time, and pull-in voltage as examples, the graphs show that the pull-in holding current has many outliers and deviates significantly from the normal range, the release time has fewer outliers and deviates less significantly from the normal range, and the pull-in voltage has no outliers. Ultimately, it was observed that the overtravel distance, opening distance, pull-in holding current, and contact resistance have many outliers and deviate significantly from the normal range, while the pull-in time, release time, pull-in synchronization time, and release synchronization time have fewer outliers and deviate less significantly from the normal range, and the pull-in voltage and release voltage have almost no outliers. Therefore, the overtravel distance, opening distance, pull-in holding current, and contact resistance were identified as the main characteristic parameters affecting contactor performance.

[0024] Based on the abnormal range observed by the Box-whisker plot, i.e. the value exceeding the upper and lower whisker range, and combined with practical significance, such as the lower limit of abnormal contact resistance being 0.01, and the closer the actual contact resistance is to 0, the better the contact performance, the lower limit of contact resistance is adjusted to 0; the overtravel distance should be as close as possible to the maximum value in the test results of the new product sample, the upper limit is adjusted to the maximum value of the new product sample, and the final health observation range is shown in Table 2.

[0025] Table 2 Health Observation Range of Auxiliary Variable Frequency and Voltage Transformer Circuit Contactors

[0026] Life test verification: Based on the longest actual service life of 12 years and 4 months of the sample contactor installed in the C6 overhaul process, and combined with the actual usage frequency, the actual number of operations before the next C6 overhaul was estimated, with a 30% margin. The number of life tests was determined to be 16,000 cycles. The test termination condition was set as either completing the predetermined number of operations or encountering a situation where disconnection or closure fails. Four samples were selected from both the abnormal and normal categories in the initial testing range for verification. Ultimately, 75% of the four samples drawn from the abnormal category failed to complete the predetermined number of operations, while all four samples drawn from the normal category completed the predetermined number of operations.

Claims

1. A method for studying the remaining life of locomotive contactors, characterized in that, Includes the following steps: (1) Failure mechanism analysis: Combining the stress environment, product structural characteristics, historical operation data, maintenance data and fault data of the contactor, identify the key life risk points of the contactor and their corresponding sensitive stresses, and determine the characteristic parameters to be collected, including: overtravel distance, opening distance, pull-in holding current, contact resistance, pull-in voltage, release voltage, pull-in time, release time, pull-in synchronization time, and release synchronization time. (2) Feature parameter extraction: Collect the above feature parameters of new products and actual operating contactors with different service years, record the service years, installation location and load information of each sample, and establish a contactor feature parameter database under real working conditions; (3) Status data analysis: The collected data is cleaned and classified, grouped by product model and load circuit consistency, and sorted by service life. The changing trend of each characteristic parameter with the service time is observed. (4) Health status assessment: The stability and dispersion of the characteristic parameters in each dataset are assessed by using the Box-whisker plot analysis method. The boundary of outliers is adjusted in combination with the actual physical meaning to determine the health range of each characteristic parameter and to screen out the key characteristic parameters that have a significant impact on the performance of the contactor. (5) Life test verification: Based on the actual service life and usage frequency of the contactor, estimate the number of operations required to reach the next overhaul, and reserve a margin, and set the number of life tests; samples are drawn from outside and outside the health range to conduct life tests to verify the effectiveness of the health range assessment model. (6) Establishment of remaining life assessment model: Based on the health threshold of key characteristic parameters and their correlation with life, a contactor remaining life assessment model is constructed to predict whether the contactor can operate safely until the next maintenance cycle.

2. The method for studying the remaining life of a locomotive contactor according to claim 1, characterized in that: The method focuses on the remaining life of contactors during the C6 overhaul stage of HXD1 series electric locomotives.

3. The method for studying the remaining life of a locomotive contactor according to claim 1, characterized in that: In the health status assessment step, key characteristic parameters include overtravel distance, opening distance, pull-in maintenance current, and contact resistance.

4. The method for studying the remaining life of a locomotive contactor according to claim 1, characterized in that: In the life test verification step, the test is terminated when a predetermined number of actions are completed or the contactor fails to close / open normally.

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