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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工业上常用的继电器的功能有哪些

2013/12/11 6:22:25点击:
核心提示:继电器这种工业上常见的一种电器,我们都知道继电器是一种根据特定输入信号而动作的自动控制电器,其种类很多,有中间继电器、热继电器、时间继电器等类型继电器这种工业上常见的一种电器,我们都知道继电器是一种根据特定输入信号而动作的自动控制电器,其种类很多,有中间继电器、热继电器、时间继电器等类型。 KM中间继电器通常用来传递信号和同时控制多个电路,也可用来直接控制小容量电动机或其他电气执行元件。中间继电器的结构和工作原理与交流接触器基本相同,与交流接触器的主要区别是触点数目多些,且触点容量小,只允许通过小电流。在选用中间继电器时,主要是考虑电压等级和触点数目。 FR热继电器下层金属膨胀系数大,上层的膨胀系数小。当主电路中电流超过容许值而使双金属片受热时,双金属片的自由端便向上弯曲超出扣板,扣板在弹簧的拉力下将常闭触点断开。触点是接在电动机的控制电路中的,控制电路断开便使接触器的线圈断电,从而断开电动机的主电路。 KT时间继电器通电延时空气式时间继电器利用空气的阻尼作用达到动作延时的目的。吸引线圈通电后将衔铁吸下,使衔铁与活塞杆之间有一段距离。在释放弹簧作用下,活塞杆向下移动。在伞形活塞的表面固定有一层橡皮膜,活塞向下移动时,膜上面会造成空气稀薄的空间,活塞受到下面空气的压力,不能迅速下移。当空气由进气孔进入时,活塞才逐渐下移。移动到最后位置时,杠杆使微动开关动作。延时时间即为从电磁铁吸引线圈通电时刻起到微动开关动作时为止的这段时间。通过调节螺钉调节进气孔的大小就可调节延时时间。吸引线圈断电后,依靠复位弹簧的作用而复原。空气经出气孔被迅速排出。此时间继电器有两个延时触点:一个是延时断开的常闭触点,—个是延时闭合的常开触点,此外还有两个瞬动触点。