Tracking Test ApparatusBy simulating the failure process of insulation materials under the combined action of electric field and pollution, evaluate their resistance to leakage and tracking performance. As the core component, the geometric accuracy, surface state, and stability of the electrode system directly affect the test results of CTI (compared to the tracking index) and PTI (resistance to tracking index). Optimizing electrode system design has become a key path to improving experimental accuracy and repeatability.
1、 Electrode geometric accuracy control: eliminating the source of system errors
The IEC 60112 standard strictly specifies the size (top radius 0.5 ± 0.05mm), angle (60 °± 5 °), and spacing (4.0 ± 0.1mm) of platinum electrodes. Traditional processing techniques can easily lead to electrode tip arc radius deviation>0.02mm, resulting in uneven electric field distribution and causing the droplet bridging discharge path to deviate from the theoretical value. By using CNC microelectrode grinding technology combined with laser interferometer detection, the radius error can be controlled within ± 0.005mm; The electrode angle is injection molded through a three-dimensional mold to ensure batch consistency. The experimental data shows that the fluctuation range of CTI test results of the optimized electrode system has been reduced from ± 3% to ± 1%.
2、 Surface state stability: suppresses long-term test drift
Oxidation or contamination of the platinum electrode surface can alter the contact angle and conductivity, leading to ineffective droplet volume control (standard requirement 50 ± 5 μ L). The solution includes: ① using diamond-like carbon (DLC) coating instead of traditional polishing process, which increases the surface hardness of the electrode by 10 times and extends the corrosion resistance period to over 1000 hours; ② Integrated ultrasonic cleaning module, automatically removes residues after each test to avoid cross contamination. A third-party testing agency found that the DLC coated electrode consistently had a droplet contact angle deviation of<2 ° in 100 consecutive tests, significantly better than the untreated electrode (deviation>5 °).
3、 Rigid design of mechanical structure: reducing external interference
The micrometer level displacement of electrodes during the experiment can cause a deviation in the discharge path. By optimizing the electrode support structure through finite element analysis (FEA) and using titanium alloy material (elastic modulus of 110GPa) and three-point positioning clamping method, the vibration transmission rate can be reduced to below 0.05%. In addition, a temperature compensation module is added to calibrate the thermal expansion coefficient of electrode spacing in real-time in an environment of 30-60 ℃ (the CTE of platinum is 9 × 10 ⁻⁶/℃), avoiding geometric deformation errors in high-temperature tests.
4、 Intelligent calibration and monitoring: full process quality control
The integrated machine vision system monitors the real-time status of electrode tips and identifies radius changes through image algorithms (resolution 0.001mm); The pressure sensor generates pressure fluctuations (with an accuracy of ± 0.1kPa) through the feedback of liquid droplets, and automatically triggers the calibration program. After applying this scheme, the experimental repeatability (RSD) of a certain enterprise increased from 4.2% to 1.8%, meeting the high-level requirements of ASTM D3638 standard.
The geometric accuracy, surface stability, and mechanical rigidity optimization of the electrode system, combined with intelligent calibration technology, can be significantly improvedTracking Test ApparatusAccuracy and repeatability. In the future, the combination of digital twins and AI algorithms for predictive maintenance technology will further promote the development of electrode systems towards high reliability throughout their entire lifecycle.
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