“According to the tracking test standards, the tracking resistance performance of ethylene-propylene rubber is evaluated, the characteristic quantities of tracking faults are extracted, the tracking fault diagnosis method is studied, and the surface tracking state of the ethylene-propylene rubber is evaluated.
Experiment Name: Application of High Voltage Amplifier in the Analysis of Surface Trace Corrosion Degree Based on Insulation Resistance
According to the tracking test standards, the tracking resistance performance of ethylene-propylene rubber is evaluated, the characteristic quantities of tracking faults are extracted, the tracking fault diagnosis method is studied, and the surface tracking state of the ethylene-propylene rubber is evaluated.
Experimental equipment: Ethylene-propylene rubber with different degrees of tracking treatment, ATA-7020 high-voltage amplifier, three-electrode system, drying oven
On the basis of the tracking test, after the end of the test, the insulation performance of each ethylene-propylene rubber sample was measured, and its insulation resistance was analyzed based on the volume resistance, polarization-depolarization current and recovery voltage. First, the volume resistance, polarization-depolarization current, and recovery voltage of each sample at different measurement voltages and measurement temperatures were measured in the drying oven; secondly, the volume resistance, polarization-depolarization, and the effect of different failure levels were analyzed in detail. The influence of chemical current and return voltage; finally, the insulation resistance under different measurement methods is compared to verify the reliability of the method.
(1) Polarization-depolarization current of ethylene propylene rubber;
The figure below shows the polarization-depolarization current measurement circuit diagram. During the depolarization process, the current flowing through the ethylene-propylene rubber insulation is capacitive, and the magnitude of this capacitive current is pA. Therefore, if you want to accurately measure the depolarization current, you have higher requirements on the measurement equipment. In the measurement system, the KEITHLEY-6517B is selected as the ammeter, and the ATA-7020 high-voltage amplifier is selected as the high-voltage DC power supply in the measurement. This DC source has the advantage of low noise and can ensure the reliability of the measurement data. The electrode selected in the measurement is a three-electrode structure, in which the high-voltage terminal and the measuring terminal are used for polarization-depolarization current measurement. The upper computer transmits the data collected by 6517B in real time to the upper computer for storage through the serial port.
(2) The recovery voltage of ethylene propylene rubber.
The recovery voltage method is a research based on the theory of dielectric response, and it is a way to characterize the polarization of dielectrics in the time domain. During the measurement process, the return voltage is not easily affected by external electromagnetic interference, and the measurement result is relatively stable and easy to observe.
The measuring circuit of the return voltage is shown in the figure. The DC voltage source selected for the measurement is the ATA-7020 high-voltage amplifier, and the voltage value selected during the measurement is 400V. The voltage measurement range of the KEITHLEY-6517B voltage measurement unit fully meets the measurement requirements. After the measurement, the upper computer transmits the data collected by 6517B in real time to the upper computer through the serial port to save.
(1) The influence of electric track size
In the initial stage of discharge, as the degree of tracking corrosion deepens, the initial current and the discharge speed during the depolarization process gradually increase, and the more serious the degree of tracking corrosion, the greater the current value at the time when the depolarization current decays and stabilizes. big. It can be seen from the test results that
There are obvious differences in the depolarization current curves of each sample. The attenuation of the depolarization current has a pit in the entire depolarization process.
Depolarization currents at different stages of tracking development Depolarization currents at different stages of tracking development in a logarithmic coordinate system
(2) With the increase of trace corrosion and insulation pollution, the volume resistance of ethylene-propylene rubber gradually decreases, and the polarization-depolarization current and return voltage gradually increase. That is, the magnitude and change of insulation resistance, polarization-depolarization current, and return voltage can reflect the insulation failure.
Recovery voltage under different levels of tracking corrosion Recovery voltage under different levels of toner contamination