Mike Krzyzewski is really a famous coach of Dream Team. She has coached north america men's basketball team for some time, that's clinched numerous medals for his country. Following Londonfl jerseys supplyn Olympic was over, Krzyzewski told The Associated Press that this game will be his final one as national coach, a job he's held for seven years. He had left open the possibility of swomen nfl jerseystaying with the team beyond the London Games, when practice on Saturday said these will be his last Olympics.When asked if he was sure, Krzyzewski didn't hesitate before again saying, "yecheap nfl jerseys wholesales," this will be his last game "If we could win it, then it might be three major championships in a row, i always do not know when that has been done because we haven't usually won http://govoriotkrito.bg/libs/nflcn08.htmthe globe championships," Krzyzewski said. "It becomes an enormous thing for the program." Whatever, he's an awesome coach. His achievement are going to be remembered by the country.cheap nfl jerseys

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              影響真空開關電壽命的因素

              2013/11/18 12:44:53      點擊:
                   目前許多國外同類產品如日本東芝公司10kV斷路器只要求彈跳小于10ms,新型觸頭材料的應用為合閘彈跳時間突破2ms創造了條件。目前許多真空滅弧室規定的合閘彈跳時間都大于2ms,僅要求小于3ms,甚至5ms。

                 真正影響真空開關的電壽命有影響的因素是:合閘過程中,觸頭剛接觸直至觸頭穩定接觸瞬間為止,這期間的觸頭斷開時間。真空斷路器合閘過程中,觸頭接觸后彈跳時間不應大于2ms,這也與實際工作有差異。
                   合閘彈跳是真空斷路器機械特性的重要參數,它影響到滅弧室的電壽命。而采用緩沖機構減小彈跳的方法又會影響到斷路器工作的可靠性。
               《35kV戶內高壓真空斷路器通用技術條件》(ZBK97004—89)將合閘彈跳定義為斷路器在合閘時觸頭剛接觸直至觸頭穩定接觸瞬間為止的時間。所有直讀數據的開關特性測試儀都是按照這個定義來設計制造的。影響滅弧室電壽命的是電弧,而電弧只有在動靜觸頭不接觸時才會產生,在動靜觸頭接觸時不會產生。
                真空斷路器分合電路的工作是由真空滅弧室來完成的,開關的參數必須滿足滅弧室的性能要求,如滅弧室要求合閘速度為0.4~1.0m/s,開關的速度能夠在0.3~0.7m/s之間,那么配該型號滅弧室的真空斷路器其合閘速度必須調整在0.4~0.7m/s之間,同樣,如果真空滅弧室合閘彈跳要求不大于5ms,那么配該型號滅弧室的斷路器其合閘彈跳的允許范圍也是不大于5ms。是不是應將合閘彈跳一律定為不大于2ms是值得探討的。技術不斷地在更新,在發展,標準也應不斷地完善,新型觸頭材料抗熔焊性能極好,在發生熔焊時,熔焊點呈脆性,熔焊層機械強度小,破壞熔焊所需的力小于真空斷路器的分閘力。

              永久免费的无码中文影视
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