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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影响真空开关电寿命的因素

2013/11/18 12:44:53      点击:
     目前许多国外同类产品如日本东芝公司10kV断路器只要求弹跳小于10ms,新型触头材料的应用为合闸弹跳时间突破2ms创造了条件。目前许多真空灭弧室规定的合闸弹跳时间都大于2ms,仅要求小于3ms,甚至5ms。

   真正影响真空开关的电寿命有影响的因素是:合闸过程中,触头刚接触直至触头稳定接触瞬间为止,这期间的触头断开时间。真空断路器合闸过程中,触头接触后弹跳时间不应大于2ms,这也与实际工作有差异。
     合闸弹跳是真空断路器机械特性的重要参数,它影响到灭弧室的电寿命。而采用缓冲机构减小弹跳的方法又会影响到断路器工作的可靠性。
 《35kV户内高压真空断路器通用技术条件》(ZBK97004—89)将合闸弹跳定义为断路器在合闸时触头刚接触直至触头稳定接触瞬间为止的时间。所有直读数据的开关特性测试仪都是按照这个定义来设计制造的。影响灭弧室电寿命的是电弧,而电弧只有在动静触头不接触时才会产生,在动静触头接触时不会产生。
  真空断路器分合电路的工作是由真空灭弧室来完成的,开关的参数必须满足灭弧室的性能要求,如灭弧室要求合闸速度为0.4~1.0m/s,开关的速度能够在0.3~0.7m/s之间,那么配该型号灭弧室的真空断路器其合闸速度必须调整在0.4~0.7m/s之间,同样,如果真空灭弧室合闸弹跳要求不大于5ms,那么配该型号灭弧室的断路器其合闸弹跳的允许范围也是不大于5ms。是不是应将合闸弹跳一律定为不大于2ms是值得探讨的。技术不断地在更新,在发展,标准也应不断地完善,新型触头材料抗熔焊性能极好,在发生熔焊时,熔焊点呈脆性,熔焊层机械强度小,破坏熔焊所需的力小于真空断路器的分闸力。

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