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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时间继电器继电保护

2014/1/22 19:15:13点击:
时间继电器继电保护
电力系统继电保护时间继电器分为电磁式时间继电器和集成电路静态时间继电器两种,时间继电器专用于电力系统二次回路继电保护及自动控制回路中,时间继电器作为延时装置, 使被控元件得到所需延时。
继电器是带有延时机构的螺管线圈式继电器,时间继电器具有交流和直流规格。继电器的交流规格继电器内部装有桥式整流器,将交流电源整流后供给电磁机构,每台继电器具有两副瞬时转换触点,一副滑动延时触点,一副延时主触点。当加电压于线圈两端时,唧子(铁心)克服塔形弹簧的反作用力被吸入,瞬时转换触点进行瞬时转换,同时延时机构启动,经过一定的延时,然后闭合滑动延时触点和延时主触点。主触点接触后由于上挡限制机构的转动,机构停止,时间继电器从而得到所需延时。当线圈断电时,在塔形弹簧的作用下,使唧子和延时机构返回原位。
继电器通常不带电,施加额定电压后,继电器内部瞬动继电器动作、同时晶振起振, 产生时钟脉冲,经分频后由计数器计脉冲数,时间继电器当所计脉冲数达到延时整 定值时,触发器翻转,时间继电器驱动出口继电器动作,实现所需延时,时间继电器由于采用了晶体振荡器并增加时间补偿预置电路,时间继电器对于极短的延时值也严格符合整定值,具有极高的精度。