单相供用电系统故障漏电电流特征及保护方法

为解决供用电系统和用电设备的正常漏电电流与故障漏电电流的保护和识别问题,首先针对供用电系统和用电设备的漏电特征进行分析,明确正常漏电与故障漏电的识别特征;其次分析高频电力电子设备的漏电电流特征,提出基于高频电流负反馈的磁调制漏电电流量测方法,实现故障漏电的准确检测与保护;最后提出基于漏电电流阻容特征的单相供用电系统的漏电保护策略,分别设置故障漏电动作阈值和正常漏电动作阈值,在保障供用电系统和用电设备正常运行的前提下实现故障漏电的准确保护。结果表明:正常漏电与故障漏电电流阻容特征不同;基于高频电流负反馈的磁调制漏电电流量测方法可以有效降低正常高频容性漏电电流的影响;基于漏电电流的阻容特征的漏电保护策略,可提高漏电保护的有效性和可靠性。

大兴机场线0.4kV系统接地故障排查与治理

文章分析了0.4kV开关柜接地故障保护技术原理,综述了引起大兴机场线变电站0.4kV开关柜接地故障保护功能频繁动作的7种原因和排查过程,为大兴机场线0.4kV设备平稳运行奠定了坚实的基础。

低压成套开关设备保护电路的连续性分析

阐述低压成套开关设备的特点,低压成套开关设备保护电路的应用,低压成套开关设备保护电路的连续性分析,包括附加直流电保护、零序电流保护、零序功率方向保护、漏电故障保护。

Elimination of ESD Events and Optimizing Waterjet Deflash Process for Reduction of Leakage Current Failures on QFN-mr Leadframe Devices

This technical paper presents the resolution of high leakage current failures on QFN-mr （Quad-Flat No-leads Multi-Row） LF （leadframe） devices by optimizing the waterjet deflash process and eliminating the ESD （electrostatic discharge） events. ESD damage to units can cause permanent or latent product failures which results in low final test yield, and worse, possible external customer complaints. The use of CO2 （carbon dioxide） bubbler was able to reduce the DI （deionized） water’s equivalent resistivity from 17 M？ to 0.30 M？, minimizing the tribocharging effect produced during the waterjet deflash process. Moreover, ESD events were eliminated by grounding the floating assembly equipment parts and installing appropriate ESD controls. It is of high importance to reduce or eliminate the leakage current failures to ensure the product quality, especially as the market becomes more demanding. After the optimization and implementation of the corrective and improvement actions, high leakage current occurrence was significantly reduced from baseline of 5,784 ppm to 20 ppm.