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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电力变压器安装工艺

2014-1-21 8:32:56      点击:
电力变压器 安装工艺变压器英文名称(transformer) [trAns'fC:mE(r),tra:-]。
变压器是变换交流电压、电流和阻抗的器件,当初级线圈中通有交流电流时,铁芯(或磁芯)中便产生交流磁通,使次级线圈中感应出电压(或电流)。变压器由铁芯(或磁芯)和线圈组成,线圈有两个或两个的绕组,其中接电源的绕组叫初级线圈,其余的绕组叫次级线圈。变压器是一种常见的电子元件和电气设备, 可用来把某种数值的交变电压变换为同频率的另一数值的交变电压,也可以改变交流电的数值及变换阻抗或改变相位或变换频率。为什么需要电力变压器。发电厂欲将P=sqrt(3)*UIcosφ的电功率输送到用电的区域,在P、cosφ为一定值时,若采用的电压愈高,则输电线路中的电流愈小,因而可以减少输电线路上的损耗,节约导电材料。所以远距离输电采用高电压是最为经济的。我国交流输电的电压最高已达500kV。这样高的电压,无论从发电机的安全运行方面或是从制造成本方面考虑,都不允许由发电机直接生产。发电机的输出电压一般3.15kV6.3kV、10.5 kV、 15.75 kV等几种,因此必须用升压变压器将电压升高才能远距离输送。为什么需要配电变压器:电能输送到用电区域后,为了适应用电设备的电压要求,还需通过各级变电站(所)利用变压器将电压降低为各类电器所需要的电压值。
在用电方面,多数用电器所需电压是380V、220V或36 V,少数电机也采用3kV、6kV等。