ISSN   1004-0595

CN  62-1224/O4

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核级设备危险频率下的电接触摩擦磨损试验与模拟研究

Experimental Test and Simulation of the Tribological Performance of Electrical Contact at the Dangerous Frequency of Nuclear Safety-Related DCS Equipment

  • 摘要: 针对核安全级DCS (Distributed Control System)设备在其服役过程中存在的电接触磨损问题,本研究首先对安全级DCS设备进行扫频试验,在得到设备的危险频率后,搭建电接触摩擦磨损试验台,并进行一系列摩擦学试验. 结合电—热—机顺序耦合分析法与Archard磨损模型,探索电流大小对电接触摩擦磨损的影响. 结果表明:核安全级DCS设备的一阶共振频率为12 Hz. 在该频率激励下,随着输入电流增大,电接触界面摩擦系数表现出先减小后增大的现象. 电接触表面表现出磨粒磨损、剥层和电弧烧蚀的特点. 增大电流虽然导致界面磨损加剧,但是高温下的材料软化使得接触区域增大,有利于电接触保持更长时间的低电阻状态. 但是,大电流作用下磨损表面分布不均匀,接触电阻的波动频率显著增加. 有限元分析较好地模拟电接触摩擦磨损过程. 但是由于电接触状态下,摩擦区域的接触应力有所差异,因此磨痕区的磨损深度各不相同. 在磨痕两侧,增大电流导致磨痕深度加剧,而在磨痕中间区域,输入电流为2 A时的磨痕深度明显大于输入电流为1 A和3 A的状态,这也与试验的结果保持一致.

     

    Abstract: Nuclear power safety level DCS mainly completes the safe shutdown of nuclear power plant reactors and accident mitigation functions, and is called as an emergency braking system of reactors. Therefore, the reliability and stability of nuclear power safety level DCS is the key to ensure the safe operation of reactors. However, the use of a large number of electronic connectors in nuclear power safety level DCS leads to possible friction and wear problems, which brings serious safety risks to the reliable control of the reactor. In order to address the issue of electrical contact wear in nuclear safety-related DCS device during their service life, the tribological behaviors of electronic connectors in nuclear safety level DCS were studied by means of experimental tests and numerical simulation, focusing on the friction and wear behaviors of electrical contact interfaces at different current currents. Firstly, the frequency scanning test on the safety-related DCS devices was conducted firstly, to determine its critical frequencies. Subsequently, an experimental platform for electrical contact friction and wear was established, and a series of tribological experimental tests were carried out. By combining the sequential coupling analysis method of electricity-thermal-mechanics with Archard's wear model, the influence of current magnitude on electrical contact friction and wear was explored. The experimental and simulation results indicated that the resonant vibrations corresponding to primary modes occurred at approximately 12 Hz for nuclear safety related DCS equipment, suggesting that 12 Hz was the hazardous frequency of the equipment and would be used for subsequent electrical contact tribology tests. Under this excitation frequency, as the input current increased, the friction coefficient at the electrical contact interface exhibited a phenomenon of initially decreasing and then increasing. The electrical contact surface showed wear characteristics such as abrasive particle wear, delamination, and arc erosion. Although increasing current intensified the interface wear, the material softening at high temperatures resulted in an enlarged contact area which favored maintaining a low-resistance state of electrical contact interface for a longer time period. However, under high currents, uneven distribution of worn surfaces occurred and there was a significant increase in fluctuation frequency of contact resistance. Finite element analysis could effectively simulate the process of electrical contact friction and wear. However, due to different stress distributions within the friction region under electrically contacted conditions, varying depths of wear grooves could be observed. On both sides of these grooves, increasing current led to deeper groove depths while in the middle region between them, groove depth at an input current level of 2 A was significantly greater than those at input levels of 1 A and 3 A which was consistent with experimental results. The results of this study had a certain significance for recognizing the tribological characteristics of nuclear safety DCS electrical contact.

     

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