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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    避雷器特性

    2014/1/14 8:37:16      點擊:
    避雷器 七大特性:
    一、氧化鋅避雷器的通流能力大
    這主要體現(xiàn)在避雷器具有吸收各種雷電過電壓、工頻暫態(tài)過電壓、操作過電壓的能力。川泰生產(chǎn)的氧化鋅避雷器的通流能力完全符合甚至高于國家標準的要求。線路放電等級、能量吸收能力、4/10納秒大電流沖擊耐受、2ms方波通流能力等指標達到了國內(nèi)領(lǐng)先水平。
    二、氧化鋅避雷器的保護特性優(yōu)異
    氧化鋅避雷器是用來保護電力系統(tǒng)中各種電器設(shè)備免受過電壓損壞的電器產(chǎn)品,具有良好保護性能。因為氧化鋅閥片的非線性伏安特性十分優(yōu)良,使得在正常工作電壓下僅有幾百微安的電流通過,便于設(shè)計成無間隙結(jié)構(gòu),使其具備保護性能好、重量輕、尺寸小的特征。當過電壓侵入時,流過閥片的電流迅速增大,同時限制了過電壓的幅值,釋放了過電壓的能量,此后氧化鋅閥片又恢復(fù)高阻狀態(tài),使電力系統(tǒng)正常工作。
    三、氧化鋅避雷器的密封性能良好
    避雷器元件采用老化性能好、氣密性好的優(yōu)質(zhì)復(fù)合外套,采用控制密封圈壓縮量和增涂密封膠等措施,陶瓷外套作為密封材料,確保密封可靠,使避雷器的性能穩(wěn)定。
    四、氧化鋅避雷器的機械性能
    主要考慮以下三方面因素:
    ⑴承受的地震力;
    ⑵作用于避雷器上的最大風(fēng)壓力
    ⑶避雷器的頂端承受導(dǎo)線的最大允許拉力。
    五、氧化鋅避雷器的良好的解污穢性能
    無間隙氧化鋅避雷器具有較高的耐污穢性能。
    目前國家標準規(guī)定的爬電比距等級為:
    ⑴II級 中等污穢地區(qū):爬電比距20mm/kv
    ⑵III級 重污穢地區(qū):爬電比距25mm/kv
    ⑶IV級 特重污穢地區(qū):爬電比距31mm/kv
    六、氧化鋅避雷器的高運行可靠性
    長期運行的可靠性取決于產(chǎn)品的質(zhì)量,及對產(chǎn)品的選型是否合理。影響它的產(chǎn)品質(zhì)量主要有以下三方面:
    A 避雷器整體結(jié)構(gòu)的合理性;
    B 氧化鋅閥片的伏安特性及耐老化特性
    C 避雷器的密封性能。
    七、工頻耐受能力
    由于電力系統(tǒng)中如單相接地、長線電容效應(yīng)以及甩負荷等各種原因,會引起工頻電壓的升高或產(chǎn)生幅值較高的暫態(tài)過電壓,避雷器具有在一定時間內(nèi)承受一定工頻電壓升高能力。
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