Research on two-dimensional electric field measurement system for electrical tree detection in insulating materials

At present, there is a lack of effective means to observe the growth and development of electrical trees growing inside opaque insulating materials such as oil-impregnated pressboards in real time, which hampers the defect diagnosis and insulation fault warning. The previous one-dimensional direction electric field measurement system has successfully realized the real-time detection and recording of the electrical trees growth process, which also provides experience and feasibility guarantee for the two-dimensional boundary electric field measurement system proposed in this paper for the long-term real-time detection of the electrical tree growth process on the two-dimensional plane. Seventy-two measuring electrodes were arranged on a two-dimensional plane as voltage sampling points, and two STM32F407ZGT6 micro controllers were used as control chips and sampling chips respectively. The control chip sends PWM waves to trigger the ADCs of the acquisition and storage chip to sample and control the 8-choice analog switch 74HC4051 to expand the ADC channel, and the acquisition and storage chip samples voltage signals at the sampling point in real time, and uses its own USB OTG HS function module to store the collected data to the USB disk. The signal sent by the signal generator is used to replace the voltage signal of the sampling point in the high voltage partial discharge experiment to verify the function realization degree of the system, and the back-end software is used to draw the waveform of the collected data. The experimental results show that the system can sample and store 72 voltage signals completely in real time.