正確選購單相電子式電能表 發揮電子式電能表的最優點

由于電(dian)子式電(dian)能(neng)(neng)表(biao)(biao)比感應式電(dian)能(neng)(neng)表(biao)(biao)準確度高、功耗低(di)、起動電(dian)流小、負載范圍寬、無機械磨損等諸多優(you)點(dian)，越來越廣(guang)泛地應用(yong)。但目(mu)前(qian)市場上電(dian)子式電(dian)能(neng)(neng)表(biao)(biao)廠家繁多，質(zhi)量(liang)參差不(bu)齊，選(xuan)擇不(bu)好，不(bu)僅不(bu)能(neng)(neng)發揮電(dian)子式電(dian)能(neng)(neng)表(biao)(biao)的(de)優(you)點(dian)，反而(er)會帶來不(bu)應有的(de)損失和增加維護管理的(de)工作(zuo)量(liang)。

電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)與我們熟悉的(de)(de)感應式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)(俗(su)稱機(ji)(ji)械表(biao)(biao)(biao)(biao)(biao)(biao))，既有(you)相同(tong)(tong)的(de)(de)地方，也有(you)不(bu)相同(tong)(tong)的(de)(de)地方，且不(bu)同(tong)(tong)的(de)(de)地方更多(duo)，特(te)別是(shi)表(biao)(biao)(biao)(biao)(biao)(biao)的(de)(de)內部，感應式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)是(shi)采用(yong)電(dian)(dian)(dian)(dian)(dian)磁感應元件，里面是(shi)鐵芯(xin)、鐵圈加(jia)機(ji)(ji)械傳動(dong)裝置(zhi)；而(er)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)則主要是(shi)采用(yong)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)元件，即：電(dian)(dian)(dian)(dian)(dian)阻、電(dian)(dian)(dian)(dian)(dian)容加(jia)集成電(dian)(dian)(dian)(dian)(dian)路等。因此，應根據電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)的(de)(de)這一特(te)性來(lai)進行選(xuan)(xuan)(xuan)擇(ze)(ze)。換(huan)句話說要以(yi)(yi)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)設備的(de)(de)技(ji)術(shu)(shu)要求(qiu)進行選(xuan)(xuan)(xuan)擇(ze)(ze)，而(er)不(bu)能(neng)(neng)(neng)(neng)(neng)(neng)簡單的(de)(de)照(zhao)搬以(yi)(yi)前選(xuan)(xuan)(xuan)用(yong)機(ji)(ji)械式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)的(de)(de)技(ji)術(shu)(shu)要求(qiu)選(xuan)(xuan)(xuan)擇(ze)(ze)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)(當然，也有(you)可以(yi)(yi)借鑒的(de)(de)地方)。現就我們在工作中體(ti)會，談談單相電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)(biao)(biao)(biao)的(de)(de)選(xuan)(xuan)(xuan)購，供有(you)關的(de)(de)工作人員參考(kao)。

工具/原料

目測

電工測量儀器

必要的五金工具

步驟/方法

運行中的電能表質量抽查

電(dian)(dian)表在安(an)裝運(yun)(yun)行(xing)一(yi)段時(shi)(shi)間后，必須進(jin)行(xing)抽(chou)(chou)查。抽(chou)(chou)查的(de)(de)時(shi)(shi)間間隔和(he)抽(chou)(chou)查比(bi)例(li)可(ke)以根(gen)據運(yun)(yun)行(xing)中(zhong)電(dian)(dian)能(neng)表的(de)(de)質(zhi)量(liang)情(qing)況(kuang)而定(ding)。同(tong)一(yi)廠家同(tong)一(yi)批次的(de)(de)電(dian)(dian)能(neng)表，故障率小(xiao)(xiao)、誤差變化小(xiao)(xiao)、合格率高(gao)的(de)(de)可(ke)以減少(shao)(shao)抽(chou)(chou)查比(bi)例(li)和(he)抽(chou)(chou)查時(shi)(shi)間間隔。一(yi)般情(qing)況(kuang)下(xia)，首次選(xuan)用(yong)的(de)(de)廠家產品(pin)半年內抽(chou)(chou)查率不能(neng)少(shao)(shao)于5%。一(yi)年內抽(chou)(chou)查比(bi)率不能(neng)少(shao)(shao)于10%。如果質(zhi)量(liang)穩定(ding)，誤差變化小(xiao)(xiao)，則可(ke)以減少(shao)(shao)抽(chou)(chou)查比(bi)例(li)，但每年至少(shao)(shao)要抽(chou)(chou)檢(jian)1%，以監測(ce)電(dian)(dian)能(neng)表質(zhi)量(liang)隨時(shi)(shi)間變化情(qing)況(kuang)。把(ba)電(dian)(dian)能(neng)表的(de)(de)選(xuan)購(gou)(gou)從事前選(xuan)擇延伸到(dao)整個使用(yong)過(guo)程之中(zhong)，通過(guo)監控使用(yong)中(zhong)的(de)(de)情(qing)況(kuang)，進(jin)一(yi)步提高(gao)選(xuan)購(gou)(gou)水平(ping)。

查驗生產廠家所必須具備的基本技術條件

電(dian)能表(biao)是(shi)(shi)屬國家(jia)(jia)強制(zhi)檢驗(yan)計量器具，根據(ju)計量法規定(ding)(ding)，所選電(dian)能表(biao)必須具有省級以(yi)上技(ji)術監(jian)督局頒發的(de)制(zhi)造計量器具許(xu)可證(zheng)(zheng)(CMC證(zheng)(zheng))。這是(shi)(shi)電(dian)能表(biao)生(sheng)產(chan)廠家(jia)(jia)所必須具備(bei)的(de)條件和(he)必須履行的(de)法律手續(xu)。它可以(yi)證(zheng)(zheng)明廠家(jia)(jia)具備(bei)了基本的(de)設施、人員和(he)檢測儀器設備(bei)，是(shi)(shi)可以(yi)生(sheng)產(chan)銷售的(de)產(chan)品。但是(shi)(shi)在目前市場競(jing)爭激烈(lie)的(de)情況下(xia)，供(gong)電(dian)企(qi)業有更大的(de)選擇余地，因此，還可以(yi)多比較一下(xia)其他(ta)證(zheng)(zheng)明產(chan)品質(zhi)量的(de)文件。如：權(quan)威部(bu)門(men)的(de)鑒定(ding)(ding)報(bao)告、壽命試驗(yan)報(bao)告、被列入國家(jia)(jia)經貿委“全國城鄉電(dian)網建設與(yu)改造所需設備(bei)產(chan)品及生(sheng)產(chan)企(qi)業推薦(jian)目錄”、ISO9000質(zhi)量認證(zheng)(zheng)等等。這些都是(shi)(shi)證(zheng)(zheng)明產(chan)品質(zhi)量的(de)重(zhong)要(yao)文件。

對電能表實物進行檢驗

對廠家送來的(de)電(dian)(dian)能(neng)(neng)表實物進行檢(jian)(jian)驗(yan)，主要(yao)是從以下(xia)幾個(ge)方面(mian)(mian)進行。即：機械要(yao)求(qiu)、所能(neng)(neng)適應的(de)氣候條件、電(dian)(dian)氣要(yao)求(qiu)、電(dian)(dian)磁兼容性、準確度要(yao)求(qiu)這五個(ge)方面(mian)(mian)。這五個(ge)方面(mian)(mian)在國(guo)家標準《1級(ji)和(he)2級(ji)靜止(zhi)式交流(liu)有(you)功電(dian)(dian)能(neng)(neng)表》(GB/T17215-1998)中都有(you)明確的(de)規(gui)定(ding)。規(gui)定(ding)中有(you)些試驗(yan)和(he)檢(jian)(jian)驗(yan)項目一般地市級(ji)及(ji)縣級(ji)供電(dian)(dian)企業有(you)條件檢(jian)(jian)驗(yan)，但有(you)相當多的(de)項目還不具備條件檢(jian)(jian)驗(yan)。下(xia)面(mian)(mian)將需要(yao)注意(yi)的(de)地方和(he)解決的(de)辦法做(zuo)一簡(jian)要(yao)說明。

(1)準確度要求：

準確度(du)要(yao)求包括，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)及(ji)功率因數改(gai)變、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)改(gai)變、頻(pin)率改(gai)變、起動試驗、潛力(li)試驗、走(zou)字試驗等這些(xie)項目的(de)(de)(de)(de)(de)(de)檢驗一般地市(shi)級及(ji)縣級供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)企(qi)業(ye)都能(neng)進行檢驗。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)在(zai)規(gui)程規(gui)定(ding)的(de)(de)(de)(de)(de)(de)負載(zai)范(fan)圍內，一般線性(xing)度(du)都比較好(hao)，但不同(tong)廠家的(de)(de)(de)(de)(de)(de)表(biao)實際準確計(ji)量的(de)(de)(de)(de)(de)(de)負載(zai)范(fan)圍有(you)很大差(cha)別，由于現場實際負載(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)是(shi)(shi)(shi)經常變化的(de)(de)(de)(de)(de)(de)，能(neng)準確計(ji)量的(de)(de)(de)(de)(de)(de)負載(zai)范(fan)圍越寬，表(biao)的(de)(de)(de)(de)(de)(de)負載(zai)性(xing)能(neng)越好(hao)。在(zai)農(nong)村有(you)些(xie)地區電(dian)(dian)(dian)(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)波(bo)動比較大。要(yao)注(zhu)意檢查電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)波(bo)動極限情況下(xia)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)的(de)(de)(de)(de)(de)(de)誤(wu)(wu)差(cha)。特別是(shi)(shi)(shi)低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)時(shi)的(de)(de)(de)(de)(de)(de)輕載(zai)誤(wu)(wu)差(cha)和電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)走(zou)字是(shi)(shi)(shi)否有(you)力(li)，檢查表(biao)內直(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不能(neng)下(xia)降到(dao)計(ji)量器(qi)及(ji)芯片的(de)(de)(de)(de)(de)(de)工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)以(yi)下(xia)，直(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)(de)(de)(de)波(bo)紋不能(neng)有(you)明(ming)顯地增加，中儀電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)生產的(de)(de)(de)(de)(de)(de)單相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)及(ji)三相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)質保一年，讓您(nin)用的(de)(de)(de)(de)(de)(de)放心。

準確度要求還包括，如(ru)諧(xie)波、外部(bu)磁(ci)(ci)感應、高頻電(dian)磁(ci)(ci)場影響(xiang)等。一般(ban)地(di)市級(ji)及縣級(ji)供電(dian)企業不(bu)具備條件檢(jian)驗(yan)(yan)，可以請省級(ji)電(dian)力試驗(yan)(yan)所(suo)檢(jian)驗(yan)(yan)。

(2)氣候條件和電磁兼容性能：

這兩(liang)項對電(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)(shi)(shi)電(dian)(dian)(dian)(dian)能(neng)來說都(dou)很重(zhong)要(yao)。尤其(qi)是(shi)電(dian)(dian)(dian)(dian)磁(ci)兼容性(xing)能(neng)對電(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)(shi)(shi)電(dian)(dian)(dian)(dian)能(neng)表(biao)影(ying)響(xiang)極為(wei)嚴重(zhong)，電(dian)(dian)(dian)(dian)磁(ci)兼容性(xing)能(neng)較差的表(biao)，現(xian)場(chang)運行(xing)中往(wang)往(wang)出現(xian)“死機”、“飛字”等現(xian)象，甚至內部電(dian)(dian)(dian)(dian)子(zi)(zi)元件(jian)損壞。這是(shi)電(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)(shi)(shi)電(dian)(dian)(dian)(dian)能(neng)表(biao)有別于機械(xie)式(shi)(shi)(shi)電(dian)(dian)(dian)(dian)能(neng)表(biao)的一個(ge)重(zhong)要(yao)特性(xing)。電(dian)(dian)(dian)(dian)磁(ci)兼容檢驗(yan)(yan)(yan)一共有5個(ge)項目，即(ji)：靜電(dian)(dian)(dian)(dian)放電(dian)(dian)(dian)(dian)試驗(yan)(yan)(yan)、高頻電(dian)(dian)(dian)(dian)磁(ci)場(chang)試驗(yan)(yan)(yan)、電(dian)(dian)(dian)(dian)快速瞬變(bian)脈(mo)沖群試驗(yan)(yan)(yan)、浪涌試驗(yan)(yan)(yan)、無線電(dian)(dian)(dian)(dian)干擾抑制試驗(yan)(yan)(yan)。其(qi)中浪涌和脈(mo)沖群比較接近(jin)電(dian)(dian)(dian)(dian)網(wang)中的一些瞬態情況(kuang)，建議有條(tiao)件(jian)的地市級及縣級供電(dian)(dian)(dian)(dian)企業購置相(xiang)應設備，對電(dian)(dian)(dian)(dian)能(neng)表(biao)進行(xing)抽(chou)查(cha)檢驗(yan)(yan)(yan)。

(3)電氣要求：

電(dian)(dian)(dian)(dian)(dian)(dian)氣要(yao)求的(de)(de)功率(lv)消耗檢驗(yan)(yan)，包括電(dian)(dian)(dian)(dian)(dian)(dian)壓線路和電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)線路，可以(yi)用互感器校驗(yan)(yan)儀(yi)測(ce)量(liang)電(dian)(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)和負(fu)載阻抗后(hou)，計算(suan)出(chu)額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)壓、額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)下(xia)電(dian)(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)的(de)(de)功率(lv)消耗。這種方(fang)法既準確(que)又方(fang)便(bian)；電(dian)(dian)(dian)(dian)(dian)(dian)源影響(xiang)、電(dian)(dian)(dian)(dian)(dian)(dian)壓降落和短時中斷、自熱影響(xiang)可以(yi)在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)校驗(yan)(yan)臺上模(mo)擬進行；短時過電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)會影響(xiang)檢驗(yan)(yan)，嚴格按規(gui)程(cheng)定(ding)義(yi)做(zuo)比(bi)較(jiao)困(kun)難，可以(yi)在(zai)2倍最大電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)下(xia)，逐步(bu)延(yan)長(chang)時間，檢測(ce)電(dian)(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)的(de)(de)溫升(電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)端子及取樣(yang)電(dian)(dian)(dian)(dian)(dian)(dian)阻)和誤(wu)差。這可以(yi)了解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)過負(fu)載后(hou)的(de)(de)損壞程(cheng)度(du)。

為防(fang)止低壓(ya)供電(dian)線(xian)路中性(xing)點(dian)斷開后，因負載不平衡引起某相電(dian)壓(ya)升(sheng)高(gao)燒壞電(dian)能表的情況發生，將(jiang)單相電(dian)表的輸入電(dian)壓(ya)升(sheng)高(gao)到420V，經(jing)過(guo)4小時后，再(zai)在額定(ding)電(dian)壓(ya)下檢(jian)驗電(dian)能表應合格(ge)(試驗時要有人值守(shou)，注意安全，發現(xian)有異(yi)常立即斷電(dian)檢(jian)查(cha))。

(4)機械要求：

機(ji)械要求(qiu)中的(de)(de)絕大部分內容是(shi)可(ke)以(yi)通過(guo)直觀檢(jian)(jian)查和簡單(dan)的(de)(de)試驗(yan)方法(fa)進(jin)行(xing)檢(jian)(jian)驗(yan)的(de)(de)。如：四防(fang)(防(fang)電擊(ji)；防(fang)過(guo)高溫度；防(fang)火焰蔓延；防(fang)固體異物、灰塵和水進(jin)入(ru))；鉛封(feng)(feng)方便可(ke)靠(只有破壞鉛封(feng)(feng)后才能(neng)觸及儀表內部部件)；接(jie)線(xian)端子應有足(zu)夠的(de)(de)絕緣性(xing)能(neng)和機(ji)械強度；表殼的(de)(de)結構和裝配應能(neng)保證(zheng)在出現非永久(jiu)性(xing)變(bian)形時(shi)不妨礙儀表正常工(gong)作；銘(ming)牌、接(jie)線(xian)圖、端子標志符合要求(qiu)等等。這些要求(qiu)都是(shi)保證(zheng)電能(neng)表安(an)全(quan)運行(xing)的(de)(de)最(zui)基本要求(qiu)，是(shi)可(ke)以(yi)憑經驗(yan)觀察和識別的(de)(de)。選用決不能(neng)忽視。特別端子板要選用阻(zu)燃材料，如選用注(zhu)射型酚醛樹脂；外(wai)殼采用ABS工(gong)程塑料時(shi)要注(zhu)意檢(jian)(jian)查是(shi)否阻(zu)燃；外(wai)殼不能(neng)有明顯變(bian)形影響密(mi)封(feng)(feng)性(xing)能(neng)和內部元件有明顯的(de)(de)相對(dui)位移。

注意事項

另外需(xu)要(yao)注(zhu)意的(de)(de)有(you)，由(you)于目前(qian)電(dian)(dian)(dian)子表(biao)(biao)的(de)(de)機械計量(liang)器(qi)，還(huan)沒有(you)從原理(li)上(shang)根(gen)本解決卡(ka)字問題。主要(yao)是通過(guo)選擇制(zhi)造工藝好的(de)(de)計量(liang)器(qi)和進廠時嚴格篩選保(bao)證(zheng)電(dian)(dian)(dian)能表(biao)(biao)整機質量(liang)。因此，要(yao)特別注(zhu)意計量(liang)器(qi)的(de)(de)質量(liang)。步進電(dian)(dian)(dian)機有(you)屏蔽可(ke)以(yi)防電(dian)(dian)(dian)磁(ci)干擾，外殼采用鋁合金支架、齒輪精細、無毛刺、材(cai)料不(bu)易變形、有(you)自潤滑性能、步進電(dian)(dian)(dian)機磁(ci)性能強、加工精密，都可(ke)以(yi)減少卡(ka)字的(de)(de)問題。要(yao)注(zhu)意仔細檢查和了解。再就是要(yao)進行走字檢驗。為(wei)更嚴格地考核計量(liang)器(qi)質量(liang)，保(bao)證(zheng)安(an)裝到現場(chang)的(de)(de)電(dian)(dian)(dian)能表(biao)(biao)在電(dian)(dian)(dian)壓允許范圍內(nei)都能正確計量(liang)，建議采用本地區電(dian)(dian)(dian)網可(ke)能出現的(de)(de)最低(不(bu)考慮暫態)電(dian)(dian)(dian)壓進行走字試驗。