为了提高接地网故障诊断工作效率、减轻工作量和提高测试数据精度，对由测试主控机、程控直流电流源、程控切换装置和6位半可编程控制的数字万用表四部分组成的接地网故障诊断自动测试系统关键技术问题进行了研究。 针对测试系统的主站软件设计，对串口通信模块、测试方案输入模块和数据处理等三个模块进行了开发设计，制定了主站软件与切换装置之间的通信协议，规定了数据格式和校验方法，采用对异或校验进行改进的半字节异或校验，增加了检错能力。应用RS-232串口，实现测试主控机与程控切换装置、6位半数字表之间的通信。该系统由测试主控机通过串口向程控切换装置发送控制命令，由程控切换装置切换电流激励位置和电压测量位置，并从6位半数字表采集量测数据。 测试方案输入模块对原始的方案进行映射，将一个大的方案分成若干个子方案，对于每一个子方案，在测试之前，只需人工接好激励位置和测量位置，开启装置即可自动测量。 数据处理模块对从万用表读取的数据进行直线拟合，计算拟合残差，保存拟合效果好的数据。 通过对一个60支路的实验接地网进行了自动测试与故障诊断，对所开发的系统软件进行测试，实验结果表明所开发的自动测试系统软件结构合理，功能可行，不仅可以显著减轻测试的人工工作量和避免频繁换接线带来的差错，并且所采用的对采集数据进行直线拟合处理措施能够显著提高接地网腐蚀故障诊断的精度。

To improve the working efficiency, reduce the manpower and increase the data accuracy of grounding grids corrosion diagnosis, an automatic test system is designed and studied , which consists of the host computer, the intelligent DC current source, the 6-and-a-half byte programmable and controllable digital multimeter and the program controlled switching device. As for the host software design of test system, serial communication module, test scheme input module and data processing module are designed and developed. The communication protocol between the host software and the switching device is established. The protocol defines the data format and the verification process. An half-byte exclusive-or checking is used in the verification process, which is improved to enhance the error-detecting capability. The application of RS-232 serial port can realize the communication among the host, the switching device and the digital multimeter. The host of the proposed system sends the control commands through SIO to the switching device to switch the position of the current excitation and the voltage measurement, collecting a series of test data through the digital multimeter. The input module of test scheme can map the original scheme and divide a large scheme into several sub-schemes. As for each sub-scheme, the position of excitation and measurement should be manually arranged beforehand. So as to realize the measurement by shifting the positions automatically. The data processing module can gether the data from the digital multimeter and commit a linear curve fitting on them to reduce the effect of the testing errors in the data. An exprimetal grouding grid with sixty branches is automatically tested and diagnosed to check the developed software, the results of which show that the software is feasible and that it not only considerably reduce the workload, but also avoid the mistakes caused by frequently changing the line connections manually. Further more, linear curve fitting approach of the collected data can remarkably improve the accuracy of the grouding grids corrosion diagnosis