Study of the in situ test setup and analysis methods for self-healing properties of metallized film capacitors.

Metallized film capacitors (MFCs) are widely used in the power electronics industry due to their unique self-healing (SH) capability. SH performance is an essential assessment for MFC reliability verification in industrial production. The SH phenomenon of metallized films usually occurs rapidly in a very short period, and its real-time evolution details are often difficult to capture and analyze. In this paper, a test system for the SH performance of metallized films for capacitors was constructed. The system consists of three components: a voltage-current characteristic testing and current pulse capture device, a microscopic image real-time acquisition device, and an integrated analysis processing device. Through the voltage-current characteristic testing and current pulse capture device, the electrical parameters of the SH point, such as SH times, breakdown field strength, SH current, and SH energy, are obtained; through a microscopic image real-time acquisition device, the real-time spatial positioning of the SH point was obtained, and the interconnection between the morphology of the SH point and the electrical properties was established. The relationship between the SH point and the temperature distribution was further established using thermal imaging technology, which lays the foundation for a thorough and timely assessment and analysis of the failure mechanism and the real-time evolution of the metallized film SH process. This significantly improves the effectiveness of SH property research.

[Influencing factors of mercury emission flux from forest soil at Tieshanping, Chongqing].

To study the effect of environmental influencing factors on soil mercury emissions, intact surface soil samples (0 to 5 cm) were collected from a Masson pine forest in Tieshanping, Choningng to conduct controlled experiments, and soil mercury emission flux was measured by dynamic flux chambers under different conditions. The results showed that the mercury emission significantly increased with the enhancement of solar radiation, air temperature, and soil water content. The mercury emissions in sunlight were 3 to 9 times higher than those in shade, but the latter condition should be more similar to the actual condition in the field. The mercury emission flux was significantly higher in summer than in spring and autumn, and was the lowest in winter. Higher in air temperature, soil water content had a stronger effect on soil mercury emission. Removal of litterfall significantly decreased soil mercury emission, mainly because the mercury content of litterfall was higher than that in mineral soil layer. In addition, soil mercury emission had an obvious trend of decay during a day, indicating that relatively low mercury content in forest soil might be a limiting factor of mercury emission. The mercury emission flux in the daytime measured in this study was( 14.3 +/- 19.6) ng. (m2 .h) -1 in summer, (3.50 +/-5. 36)ng- (m2 h)-1 in spring and autumn, and (1.48 +/-3. 27)ng- (m2 h)-1 in winter. The steady-state results above might therefore be overestimation of the actual emission in the field.

[Field measurement of soil mercury emission in a Masson pine forest in Tieshanping, Chongqing in Southwestern China].

To investigate soil mercury emission characteristics in areas with high atmospheric mercury concentration, the soil-air exchanging flux of gaseous elemental mercury (Hg0) was measured for four seasons from September 2012 to July 2013 in a Masson pine forest of Tieshanping, Chongqing in Southwestern China using a dynamic flux chamber and a LUMEX RA-915+ mercury analyzer. The effects of ambient air mercury concentration and environmental factors, such as radiation intensity, air temperature, air humidity, soil temperature, and soil water content, on exchanging flux were also studied. Results showed that there was obvious seasonal variation of the Hg0 exchanging flux, with the highest value of 35.3 ng · (m2 · d)(-1) in the summer and very low values in other seasons, even negative in spring and winter. In addition to radiation intensity and air/soil temperature, ambient air mercury concentration was an important impacting factor, which was negatively correlated with the Hg0 exchanging flux, with the equilibrium concentration at 5.61 ng · m(-3). The total soil emission of Hg0 was estimated to be 2.65 µg · (m2 · a)(-1), which was much lower than that in similar forests in cleaner areas. High ambient air Hg0 concentration in Tieshanping was the main reason for the difference.