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
<td id="gu7nx"><input id="gu7nx"></input></td>
<form id="gu7nx"><optgroup id="gu7nx"></optgroup></form>

    1. <style id="gu7nx"><kbd id="gu7nx"></kbd></style>

    高壓真空斷路器特點(diǎn)

    2014/1/3 8:17:43      點(diǎn)擊:
    高壓真空斷路器 的特點(diǎn)①觸頭開(kāi)距小,10KV真空斷路器的觸頭開(kāi)距只有10mm左右,操作機(jī)構(gòu)的操作功就小,機(jī)械部分行程小,其機(jī)械壽命就長(zhǎng)。
    ②燃弧時(shí)間短,且與開(kāi)關(guān)電流大小無(wú)關(guān),一般只有半周波。
    ③熄弧后觸頭間隙介質(zhì)恢復(fù)速度快,對(duì)開(kāi)斷近區(qū)故障性能較好。
    ④由于疏通在開(kāi)斷電流時(shí)磨損量較小,所以觸頭的電氣壽命長(zhǎng),滿容量開(kāi)斷達(dá)30-50次,額定電流開(kāi)斷達(dá)5000次以上,噪音小適于頻繁操作。
    ⑤體積小、重量輕。
    ⑥適用于開(kāi)斷容性負(fù)荷電流。
    由于其優(yōu)點(diǎn)很多,所以廣泛應(yīng)用于變電站中,目前型號(hào)主要有:ZN12-10型、ZN28A-10型、ZN65A-12型、ZN12A-12型、VS1型、ZN30型等。
    具體介紹

    真空斷路器技術(shù)標(biāo)準(zhǔn)真空斷路器在我國(guó)近十年來(lái)得到了蓬勃的發(fā)展。產(chǎn)品從過(guò)去的ZN1~ZN5幾個(gè)品種發(fā)展到數(shù)十多個(gè)型號(hào)、品種,額定電流達(dá)到5000A,開(kāi)斷電流達(dá)到50kA的較好水平,并已發(fā)展到電壓達(dá)35kV等級(jí)。
    80年代以前,真空斷路器處于發(fā)展的起步階段,技術(shù)上在不斷摸索,還不能制定技術(shù)標(biāo)準(zhǔn),直到1985年后才制定相關(guān)的產(chǎn)品標(biāo)準(zhǔn)。
    國(guó)內(nèi)主要依據(jù)標(biāo)準(zhǔn):
    JP3855-96《3.6~40.5kV交流高壓真空斷路器通用技術(shù)條件》
    DL403-91《10~35kV戶內(nèi)高壓斷路器訂貨技術(shù)條件》
    這里需要說(shuō)明:IEC標(biāo)準(zhǔn)中并無(wú)與我國(guó)JB3855相對(duì)應(yīng)的專用標(biāo)準(zhǔn),只是套用《IEC56交流高壓斷路器》。因此,我國(guó)真空斷路器的標(biāo)準(zhǔn)至少在下列幾個(gè)方面高于或嚴(yán)于IEC標(biāo)準(zhǔn):
    (1) 絕緣水平: 試驗(yàn)電壓 IEC 中國(guó)
    1min工頻耐壓(kV) 28 42(極間、極對(duì)地)48(斷口間)
    1.2/50沖擊耐壓(kV) 75 75(極間、極對(duì)地)84(斷口間)
    (2)電壽命試驗(yàn)結(jié)束后真空滅弧室斷口的耐壓水平:IEC56中無(wú)規(guī)定。我國(guó)JB3855一96規(guī)定為:完成電壽命次數(shù)試驗(yàn)后的真空斷路器,其斷口間絕緣能力應(yīng)不低于初始絕緣水平的80%,即工頻1min33.6kV和沖擊60kV。
    (3)觸頭合閘彈跳時(shí)間:IEC無(wú)規(guī)定,而我國(guó)規(guī)定要求不大于2ms。
    (4)溫升試驗(yàn)的試驗(yàn)電流:IEC標(biāo)準(zhǔn)中,試驗(yàn)電流就等于產(chǎn)品的額定電流。我國(guó)DL403-91中規(guī)定試驗(yàn)電流為產(chǎn)品額定電流的110%。
    2.真空斷路器的主要技術(shù)參數(shù) 真空斷路器的參數(shù),大致可劃分為選用參數(shù)和運(yùn)行參數(shù)兩個(gè)方面。前者供用戶設(shè)計(jì)選型時(shí)使用;后者則是斷路器本身的機(jī)械特性或運(yùn)動(dòng)特性,為運(yùn)行、調(diào)整的技術(shù)指標(biāo)。
    下表是選用參數(shù)的列項(xiàng)說(shuō)明,并以三種真空斷路器數(shù)據(jù)為例。
    表中所列各項(xiàng)參數(shù),均須按JB3855和DL403標(biāo)準(zhǔn)的要求,在產(chǎn)品的型式試驗(yàn)中逐項(xiàng)加以驗(yàn)證,最終數(shù)據(jù)以型式試驗(yàn)報(bào)告為準(zhǔn)。
    工作原理

    真空斷路器的工作原理是:當(dāng)動(dòng)、靜觸頭在操作機(jī)構(gòu)的作用下分閘時(shí),觸頭間產(chǎn)生電弧,觸頭表面在高溫下?lián)]發(fā)出蒸汽,由于觸頭設(shè)計(jì)為特殊形狀,在電流通過(guò)時(shí)產(chǎn)生一磁場(chǎng),電弧在此磁場(chǎng)作用下沿觸頭表面切線方向快速運(yùn)動(dòng),在金屬圓筒(屏蔽罩)上凝結(jié)了部分金屬蒸汽,電弧在自然過(guò)零時(shí)就熄滅了,觸頭間的介質(zhì)強(qiáng)度又迅速恢復(fù)起來(lái)。
    亚洲色欲大片AAA无码,欧美精品一区三区在线观看,久久精品人人做人人爽不卡,国产日韩伦精无码一区二区
    <td id="gu7nx"><input id="gu7nx"></input></td>
    <form id="gu7nx"><optgroup id="gu7nx"></optgroup></form>

    1. <style id="gu7nx"><kbd id="gu7nx"></kbd></style>