| In response to the maintenance requirements of medium and high voltage rotating machines,combined with the research status of insulating dielectric theory and the theory of computer automatic test technology,the design goal of an automatic test system for motor insulation status based on the polarization depolarization current method is proposed to solve the field test of motor insulation The problem.The analysis and research of the polarization depolarization theory and the Debye equivalent model of motor insulation show that the polarization depolarization current can be used to measure the state of motor insulation.The automatic test system selects the virtual instrument test platform and selects the data acquisition card of the USB bus.Designed a weak current signal detection circuit.After many simulations and PCB experiment optimizations,a fully differential,multilayer filtering,and three-layer PCB design was determined,and finally a weak current signal detection with a resolution of 10 n A was realized;a DC high-voltage excitation circuit was designed and adopted The high-frequency inverter,step-up transformer and diode voltage doubler rectifier circuit have the characteristics of small size and low ripple;designed the polarization depolarization measurement circuit,using high-voltage reed switch for switching;designed the visualization based on Labview The software can realize measurement,control,data processing and display in one.Finally,the automatic test system was tested.The weak current detection circuit can achieve a resolution of 10 n A,the output voltage of the DC high voltage excitation circuit is stable,and the ripple is small.The motor stator bar is tested,and the test curve is stable and meets the design requirements. |
