1、 Fault diagnosis and solution of light source system

Unstable irradiation intensity

Phenomenon: During the testing process, the irradiation value fluctuated by more than ± 5%, resulting in an uncontrollable accelerated aging rate.

Diagnosis: Check the lifespan of the xenon arc lamp (usually ≤ 2000 hours). If the lamp turns black or both ends turn purple, it needs to be replaced; Simultaneously verify whether the filter is aging (such as when the transmittance of quartz glass drops below 85%).

Solution: Regularly replace the lamp tube (recommended to replace every 1500 hours), and calibrate the transmittance of the filter with a spectrophotometer to ensure that the energy ratio in the UV zone (280-400nm) meets the standard (such as ASTMG154 requirement of ≤ 15% error).

Spectral distribution deviation

Phenomenon: The test sample exhibits unexpected failure modes (such as plastic yellowing but not cracking).

Diagnosis: Use a spectral radiometer to scan the light source output and compare it with the standard solar spectrum (AM1.5 or AM2.5). If the proportion of UV-B (280-320nm) is too high, it may cause excessive degradation of the material.

Solution: Adjust the filter combination (such as increasing the coating layer) or replace the light source type (such as replacing xenon arc lamps with metal halide lamps) to ensure a spectral matching degree of ≥ 90%.

2、 Abnormal handling of temperature and humidity control system

Temperature overshoot or fluctuation

Phenomenon: The temperature inside the box deviates from the set value (such as setting 65 ℃ but actually reaching 70 ℃), resulting in thermal stress failure of the sample.

Diagnosis: Check if the power of the heating tube matches (e.g. a 3kW heater is required for a 500L test chamber), and verify the accuracy of the temperature sensor (PT100) (± 0.1 ℃). If the sensor drifts, it needs to be recalibrated.

Solution: Adopt PID self-tuning function to optimize control parameters (such as P=2.0, I=300s, D=50s), and increase the thickness of the insulation layer (such as increasing the density of glass fiber cotton to 32kg/m ³) to reduce heat loss.

The humidity cannot meet the standard

Phenomenon: During high humidity testing, the humidity only reaches 70% RH (set at 95% RH), which affects the simulation of hydrolysis reaction.

Diagnosis: Check if the humidifier nozzle is clogged (such as scale buildup) and verify the calibration status of the humidity sensor (capacitive). If the sensor fails, it needs to be replaced and recalibrated.

Solution: Regularly clean the humidifier (recommended once a month) and use distilled water as the humidifying medium (conductivity ≤ 5 μ S/cm); At the same time, increase the sealing performance of the box (such as replacing the silicone sealing strip and controlling the compression amount within 1.5-2mm).

3、 Cycle system and safety protection optimization

Uneven wind speed

Phenomenon: The difference in wind speed inside the box is greater than 0.5m/s, resulting in uneven heating/humidity of the sample.

Diagnosis: Check whether the fan blades are deformed (such as centrifugal fan blade angle deviation>2 °), and verify the rationality of the air duct design (such as the angle of the guide plate at the corner should be ≥ 135 °).

Solution: Adjust the fan speed (recommended wind speed of 5-10m/s) and add a flow equalization plate (porosity of 40% -60%) in the air duct to reduce turbulence intensity.

Security protection failure

Phenomenon: Over temperature protection (such as setting 85 ℃ but actually reaching 100 ℃ without triggering an alarm) or leakage protection action.

Diagnosis: Check if the wiring between the temperature controller (such as Omron E5CC) and the solid-state relay (SSR) is loose, and verify the operating current of the residual current device (RCD) (recommended ≤ 30mA).

Solution: Regularly test the safety interlock function (such as simulating over temperature/leakage scenarios once a month), and replace aging components (such as SSR contacts that need to be polished or replaced due to oxidation).

4、 Conclusion

The stable operation of the solar radiation test chamber requires the establishment of a "preventive maintenance+real-time monitoring" system: daily recording of key parameters (irradiation, temperature and humidity, wind speed), monthly equipment calibration (spectra, sensors), and quarterly comprehensive inspections (electrical, mechanical). Through data-driven fault prediction, such as wind turbine life warning based on vibration analysis, the risk of unplanned downtime can be significantly reduced, ensuring the repeatability and reliability of test results.