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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相序继电器概述

2013/12/21 16:30:58点击:
相序继电器概述
相序保护用相序继电器
工作原理介绍:由运放器组成的一个相序比较器,比较电压幅值、频率高低和相位。如果条件附合放大器导通,要是有单个条件不附合放大器闭合。相序继电器主要用于相序检测或断相保护中当相序为正确时,继电器动作获得输出当相序为不正确时或交流回路任一相断线时继电器闭锁。
一般情况下,电动机工作的接线顺序是有规定的,如果由于某种原因,导致相序发生错乱,电动机将无法正常工作甚至损坏。三相电源中有A相、B相、C相,假如按ABC相序电源接入电动机,电动机是正转,那么按ACB相序电源接入电动机,电动机就是反转了。为了防止电动机反转,就加入了相序继电器,来防止进来电源相序反相,造成电动机反转。
相序保护可采用相序继电器,当电路中相序与指定相序不符时,相序继电器将触发动作,切断控制电路的电源从而达到切断电动机电源、保护电动机的目的。