http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Licheng Xing (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
-
Study of Ablation of Arc Contacts and Dynamic Contact Resistance in High Current Breaker
Licheng Xing,Xiaodong Zhang,Qingbin Tong,Gaoqi Xing 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3
The fault of power circuit breaker (PCB) can lead very serious problems, especially in high voltage–power grid. The structure of contacts may be composed of main contacts and arc contacts, and this structure can avoid ablation of main contacts efciently. It is necessary to study the eroded state of the arc contacts and the dynamic contact resistance of arc contacts to estimate the operating state of the PCB. The wear of contacts contains arc ablation and mechanical wear through the characteristics of contacts. The arc ablation is caused by the high temperature of the arc and the mechanical wear is caused by the mechanical friction of static and movable contacts. Some experiments have been done under diferent size of contacts and diferent current through them. The results show that the mechanical wear increases, sometimes heavier, with the increase of the size of fxed contacts and the decrease of the size of movable ones because the force between fxed and movable contacts becomes larger. The results also show that the ablation of arc contacts increases with the increase of current, especially when the current is up to 20 kA. With the high temperature of arc reaching the hardness point of copper, the arc ablation and mechanical erosion are increasing obviously since the contacts become soft and easy to wear. Another result of the study shows it is important to choose the material of contacts and the force between movable and fxed contacts. The harder and less resistance the material of contacts, the better the operating situation. To monitor the operating situation of the breaker, the dynamic contact resistance was measured 25 times. As a result, the dynamic contact resistance is sensitive to the current and increasing with the increase of continuous experiment time because of the increasing of metal ions. Furthermore, if the SF6 in the PCB is changes, the dynamic contact resistance would be changed. The dynamic contact resistance in this experiment varies substantially within the range of 80–250 μΩ at the current of 20 kA.
-
Baoan Ding,Juanshan Zheng,Xiezhong Wang,Licheng Zhang,De Sun,Quanhu Xing,Andrea Pirone,Baldassare Fronte 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.10
Objective: This study investigated the effects of 1,3-1,6 beta-glucan added to the diet of Haidong chicks reared under hypoxic conditions, to ascertain the growth performances, immunity and intestinal morphology changes. Methods: A total of 750 chicks were divided into five groups and fed diets containing 0.5 g/kg, 1.0 g/kg, and 2.0 g/kg 1,3-1,6 beta-glucan from yeast (G1, G2, G3, respectively), 0.2 g/kg Taylor rhizomorph and a control feed. Results: The body weight and body weight gain were higher in chicks fed 1,3-1,6 beta-glucan and Taylor rhizomorph than in control group. Feed conversion ratio significantly differed for G2 and G3 groups in comparison to control group. The relative weight of bursa was higher in G1, G2, and G3 groups. The white blood cells and lymphocytes were significantly increased in groups fed 1,3-1,6 beta-glucan. The immunoglobulin G of serum peak appeared in the G3 group. The villous height of the duodenum was higher in 1,3-1,6 beta-glucan feed groups. In the jejunum, the villous height was higher in G2 and G3 groups and crypt depth for all the groups fed β-glucan. At ileum level the villous height and crypt depth was higher for groups G1, G2, and G3. Conclusion: The growth performance of Haidong chicks is improved when 10 and 20 g/kg 1,3-1,6 beta-glucan is included in the diet; hence, it is suggested that 1,3-1,6 beta-glucan be included in poultry diet to reduce and replace the use of antibiotics.
ScienceON연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
