The influence factors experiment of poor contact discharge in indoor power grid
In order to achieve monitoring on poor contact in indoor power grid and avoid electrical fires, the discharge phenomenon caused by poor contact is experimented systematically. A discharge experiment model of poor contact is developed, in which the influence of the structural parameters of contact type and the gap distance on poor contact discharges are experimented, and the influence of the operating parameters of load type (cos φ), load current and voltage phase are experimented too. The influence factors of initial discharge and the influence regular patterns with various parameters have been obtained from a large number of experiments. Statistical results show that the discharge trend increases first and then decreases. In the range of experiment load, poor contact discharge is very sensitive to the structure parameters of contact model, in comparison, it is not sensitive to operation parameters such as load type and load current. When the phase of experiment-voltage is in the vicinity of 0°, 60°, 120°, 180°, 240°, 300°, it has intensive discharge region of poor contact, and this phenomenon has the similarity under different factors.
Electrical contact phenomena in switching technology - Arc discharges in switching contacts
Arc discharge phenomena upon opening and closure of switching contacts operated in load current ranges up to several tens amps are briefly summarized. Based on the electrical circuit conditions, different types of arc discharges will occur when contacts are opened. Such arc discharges will have certain influences on contact reliability and lifetime through material transfer and erosion, formation and deposition of arc products, and resultant increases in contact resistance. Arc discharges upon contact closure can be basically considered as breakdown, although break arc discharges can be also observed at contact bounces. Moreover, the author's recent studies indicate that the “minimum arc current value” of contact materials is not actually the lower limit of break arc occurrence and its interpretation should be changed.
Gold-alumina cermet photothermal films
Cermet films of gold and aluminum oxide were sputter deposited onto silicon substrates. These films consisted of nanometer-sized gold grains embedded in a matrix of aluminum oxide and were designed to absorb visible radiation and minimally emit infrared radiation. Ex situ and in situ spectroscopic ellipsometry were used to characterize film optical constants from deep ultraviolet to middle infrared. The optical constants, for cermet films with gold volume fractions ranging from 0 to 1, were used in predictive optical models. Thermal performance was optimized using a new algorithm based on energy balances. This algorithm weights the parameter fit in predictive optical models to an ideal reflectance spectrum. This weighting factor emphasizes fitting in more significant spectral ranges and de-emphasizes fitting in less significant wavelength ranges. Absorptivity, emissivity, and their ratio were calculated for optimized film structures.