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
你的位置:首页 > 新闻动态 > 行业新闻

选购真空断路器的要点

2013/11/18 12:46:25      点击:
    目前真空开关在国内外各个领域得到了广泛的应用,随着真空开关使用的普及和提高,广大用户愈来愈急需了解和掌握真空开关的原理、结构、使用和维护等方面的知识。

一、触头接触行程
  触头接触行程的选择必须保证触头在磨损后仍能保持一定的压力;在分闸时使动触头获得一定的初始动能,提高开关的初始分闸速度,拉断熔焊点,减小燃弧时间,提高介质恢复速度;在合闸时能利用触头弹簧得到平滑的缓冲,减小弹跳。
  开关的接触行程太小,不能保证触头在烧毁后具有的触头压力,开关的初始速度太小,影响真空断路器的开断和动热稳定性,同时产生严重的合闸弹振。开关的接触行程太大,将增加操作机构的合闸功,或者使合闸变的极不可靠。通常真空断路器的触头接触行程一般取额定开距的20%~40%,10kV真空断路器的接触行程一般取3~4mm。
二、额定开距
  真空断路器处于分闸状态时,真空开关管动、静触头之间的距离选择与真空断路器的额定电压、使用条件、开断电流的性质及触头材料、真空间隙的耐压强度等因素有关,主要取决于额定电压和触头材料。
  由于真空开关管的额定开距对绝缘性能的影响较大,当额定开距从零开距增大时,其绝缘水平也将提高,但当开距增大到一定数值时,开距对绝缘性能的影响就不大了,若进一步增大开距,将严重影响开关管的机械寿命。