Multi channel insulation resistance testing solution

1、 研制背景
Insulation testing is a part of the bus mainline safety inspection system. Due to the fact that most railway depots currently use shaking meters to measure the insulation of bus power supply lines in the absence of electricity, there are disadvantages such as manual switching and measurement for each three-phase four wire line, large manual reading errors, and data storage. Therefore, our company proposes a solution for insulation measurement of AC380V and DC600V passenger car power supply lines in the railway system, in order to further improve work efficiency and measurement accuracy.
2Design concept
In order to achieve the ability to measure the insulation values of multiple lines between AC380 (500V) and DC600 (1000V) respectively, as well as between lines and ground; Based on our mature insulation testing section, we have added channel switching function and connected it to the bus power connector to meet various combinations of insulation testing with one click. Please refer to the following figure for details:


3Overall plan
The multi-channel insulation resistance testing scheme consists of a testing system and a digital system. As shown in the figure below, the measurement system includes units such as insulation measurement, port voltage monitoring, temperature and humidity measurement, channel switching control, and power management. The digital system includes ARM core processors, WiFi modules, TFT touch displays, data storage, and communication units.
The 12V power module in the circuit can provide 5V power to the digital system on one hand, and on the other hand, it can be converted into 500V and 1000V voltages for measurement through the boost module; The information obtained from multi-channel insulation resistance value sampling, temperature and humidity detection, and clock module can be processed by the CPU, and the results can be displayed on the screen. At the same time, they can be automatically saved, uploaded to the PC, or transmitted back to the command center through WiFi; It can compare and judge the measured insulation value with the standard value under different humidity conditions, and achieve automatic alarm function for non conformance.



4Conclusion
In summary, the multi-channel insulation measuring instrument for railway passenger car power supply lines has the characteristics of small size, light weight, simple operation, friendly interface, stable performance, and high measurement accuracy. It can replace traditional megohmmeters to measure the insulation value of railway passenger car power supply lines with AC 380V and DC 600V power supply methods. During measurement, information such as train number, train number, work number, power supply system, and full/single row can be input in sequence. Its built-in software can judge whether the insulation resistance value of the passenger car power supply line is qualified based on the insulation value under different temperature and humidity conditions. The measurement data can be saved, queried, and uploaded. The customized instrument was tested on site in the railway system for two years, and its technical performance meets the requirements of relevant maintenance processes for passenger cars, and has been recognized by relevant departments.