Design Of Multi-channel Insulation Automatic Detection System For Mine 3.3kV Direct Distribution Lines

With the development of high-yield and high-efficient comprehensive mining technology of coal mine in China,the large-scale,super-hug scale modernization mine is built up gradually.While the mine scale is enlarging gradually,the quantity of the high voltage electrical equipment is also increasing substantially.The security operation of the coal mine high voltage electrical equipment is the signification premise for guaranteeing mine safety in production and decreasing mine disasters and accidents.Insulation resistance detection is the major method to reflect the insulation situation about the equipment and confirm the security operation of the equipment.It is quite meaningful to expand research on such subject for the practical engineering.Aiming at the problems of heavy workload,high risk and low efficiency in the existing insulation resistance detection,this paper designs a 12-channel insulation resistance automatic detection system for mine 3.3kV direct distribution lines,which is used to accurately detect the ground insulation resistance before the line is closed,that is,to detect the ground insulation resistance of all equipment connected with the line outlet.In this paper,the scheme of 12-channel lines to be measured for access to the detection system is studied,and the insulation resistance detection scheme of sampling current signal at high voltage side is put forward,which can avoid the influence of the remaining multi-channel non-measured lines on the detection result of the line to be measured,and the overall work flow of the detection system and the specific division of each module are established.In this paper,the hardware circuit design scheme of the detection system is introduced in detail,which mainly includes the design of power module,current signal sampling circuit,logic interlock circuit and hardware anti-interference,and then the software program design idea of the detection system is expounded,which mainly includes the selection of ADC clock frequency,the code and decode of digital signal,the establishment of communication protocol,the design of operation platform of upper computer and software anti-interference.Finally,the detection system is tested in the laboratory environment,the test results show that the detection system could accurately detect the resistance of the line to be measured according to the detection command,and send the result to the upper computer to display and storage by RS485 bus,which meets the design requirements of the detection system.In addition,this paper also uses EWB software to simulate the actual measuring environment to analyze that the influence of the measurement line and remaining non-measured lines on the detection result.The simulation results show that the AC vacuum contactor of the line to be measured will affect the detection result of the measuring loop,then shall to calculate the insulation resistance to the ground according to the equivalent insulation resistance of the AC contactor,the remaining 11-channel non-measured lines would not affect the detection result,which can meet the requirement of field measurement in practical engineering.