The Design And Implementation Of Grounding Resistance Monitoring Module Of The 240V DC Power Distribution System In Communication

The 240 V DC power supply system was the key equipment and important component of the computer room and communication equipment in the base station,which provided a reliable working power supply for the stable operation of the communication system.In the DC system the most harmful common fault was the ground fault.When the system appeared a little insulation drop or ground,the main control device and the protection device could work normally it would impact on the DC system and DC load.But when the two simultaneous grounded,it would cause circuit through the earth by positive and negative bus and would cause the protective device misoperation leaded to supply interrupt.So there must be a good grounding monitoring method to monitor the DC power supply system,and timely found and solved the problems,so as to improve the reliability of power supply system.The paper explained the design from three aspects.Demonstration program introduced the method of grounding resistance measurement.By comparing the advantages and disadvantages of several traditional grounding resistance detection methods,switching resistance detection method was proposed.The unbalanced bridge was formed through timing switch of the detection of positive and negative bus insulation resistance.So the insulation resistance value of the positive and negative bus to the earth could be detected.Then we could detect the fault branch combined with the DC leakage current sensor and determine the branch where the grounding faults emerged.Then the maintenance could carry on and the loss from grounding to the power system could be avoided.In the part of hardware design,the detailed circuit of detecting the grounding resistance was designed and introduced,including the power module,the main control module of the grounding resistance,the bus voltage monitoring module and so on.The part of software design was mainly the introduction of the system flow chart and the important modules of the program,so as to achieve the purpose of detection and monitoring,such as the program initialization,AD7888 AD conversion,etc.The grounding resistance monitoring module of the 240 V DC power distribution system in communication could meet the design requirements with the corresponding test and has been put into operation.The grounding resistance monitoring module,which was connected with the man-machine interface module and the display module,constitutes a complete 240 V DC power distribution monitoring device.The device could ensure the safe operation of DC system to a great extent.