Design Of Non-contact Electroscope With Multiple Voltage Levels

The high-voltage electroscope is a special safety tool necessary for power maintenance,used to check whether the equipment under test is voltage-carrying.At present,contact electroscopes are commonly used in the electric power industry,which are simple in structure and economical.However,they need to be in direct contact with the line when checking the voltage.The insulation requirements are harsh,and there are blind zone of power inspection,which may easily lead to false alarms.In addition,most electroscopes can only test the voltage of equipment of one voltage level.For substations with multiple voltage levels,more than six electroscopes are required,which is very inconvenient for maintenance.Therefore,it is of practical significance to study non-contact electroscopes with multiple voltage levels.Firstly,the paper analyzes the applicable places and advantages and disadvantages of ultraviolet,optical and electrical sensors,studies the principle of electrostatic induction,and derives the proportional relationship between the induced voltage of the sensor and the intensity of the electric field.On this basis,considering the measurement error,the size of the volume and the difficulty of manufacture,the flat capacitor is adopted as the electric field sensor.In view of the edge effect of the flat capacitor,the equipotential ring is added to improve its structure to reduce the power frequency electric field distortion and improve the stability of the output voltage between the plates of the sensor.Secondly,transmission line models with different voltage levels,different arrangement modes and different circuit numbers are established to analyze the distribution law of electric field from vertical path and horizontal path respectively.The anti-interference performance of the sensor is analyzed under the condition of line erection on the same pole and line lack of phase.Considering the problems existing in the current high-voltage electroscope — blind zone of power inspection and alarm for power failure,the alarm threshold range of different voltage levels is analyzed and set,and realize the safe and reliable electrical inspection of the line.Thirdly,establish system framework,design and debug hardware circuit and software program,realize circuit self-check,voltage grade selection,data acquisition and processing,sound and light alarm and other functions.Develop an electrical inspection monitoring platform,through Bluetooth wireless transmission of electrical inspection data,to achieve multiple alarm methods.In addition to the above work,the paper designs and prints the three-dimensional shell,and completes the overall debugging and assembly of the electroscope.Finally,the experiment platform was established to calibrate and test the electroscope.The simulation test includes the conditioning circuit test and the linearity test.In the conditioning circuit test,the ideal input signal is applied to detect the performance of the circuit.The output voltage waveform of voltage following,filtering and full-wave precision rectification is good and meets the expectation.The linear correlation coefficient between the output voltage and the input voltage is approximately 1,and the working performance is normal.The linearity experiment results showed that the induction voltage of the sensor changes synchronously with the electric field strength of the environment,which meets the requirement of non-contact measurement.The performance experiment is carried out in the high-voltage test platform.The results showed that the accuracy of the electrical test under the voltage levels of 10 k V,66 k V,110 k V and 220 k V was 100%,and the linear correlation coefficients of induced voltage and electric field strength were 0.9991,0.9954,0.9984 and0.9988,both greater than 0.99.The sensor’s induced voltage has a high linear relationship with the electric field intensity,which can accurately and reliably verify the voltage.In summary,the designed non-contact electroscope with multiple voltage levels is suitable for electrical equipment with voltage levels of 10 k V,66 k V,110 k V and 220 k V.The electrical test results are reliable and intuitive,and the operation is safe and convenient.