Design And Implementation Of Dual Channel Automatic High Voltage Direct Current Insulation Resistance Tester

The insulation resistance test project of cable network is the necessary process before cable workshop production to be put to use.Cable network is generally composed of multiple multi-core cables,outer insulation skin and related electrical connectors.By testing the insulation resistance of cable network,we can find out whether there are any cable network connection errors in the production process or the connectors should not be connected by mistake before the products leave the factory to ensure the quality of products.At present,the instrument for measuring the insulation resistance of the complex large-scale cable network produced by our factory is an old-fashioned manual megohm meter produced in 1990 s,which occupies a lot of labor costs and material resources and can not meet the requirements of workshop production and inspection tasks.Through visiting and investigating the workshop operators and quality inspectors,it is found that they have urgent needs to test the complex cable network quickly.In this paper,the principle of the previous generation megaohmmeter is investigated,and a scheme of the insulation resistance tester is put forward,which is composed of the upper computer software to control human-computer interaction,the lower computer hardware to switch test points according to test and collect resistance data.The host computer software includes four parts: insulation test module,test result save module,calibration resistance module and voltage calibration channel module.The insulation test module tests the insulation resistance of the cable network and displays it on the system desktop;the test result save module saves the test results to the computer hard disk for viewing or printing;the voltage calibration channel module calibrates the power supply voltage generated by the power board;and the calibration resistance module obtains the calibration data of the resistance test through the standard resistance box.The slave computer is composed of the control board of the FPGA,the sampling board of ADC,the relay switch board and the high voltage power supply board.The control board of the FPGA receives the control command from the upper computer and transmits the test data back to the upper computer.The high voltage power supply board generates different voltages.The relay switch board controls the switch of relays at different points by the command from the control board of the FPGA.The ADC sampling board collects the total voltage value and the voltage value across the device.After the development of the equipment,the staff of the workshop and the megaohmmeter being used in the workshop been compared under the same conditions.The staff generally think that the insulation resistance tester have simply operation,friendly human-cumputer interface,fast testing speed,high testing accuracy,no leakage and error detection,and greatly improved work efficiency.Overall,the research goal of the subject was realized.