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)(dian)(dian)子(zi)式(shi)電(dian)(dian)(dian)能表(biao)比(bi)感應式(shi)電(dian)(dian)(dian)能表(biao)準確度高、功耗低(di)、起(qi)動電(dian)(dian)(dian)流小、負載(zai)范(fan)圍寬、無機(ji)械(xie)磨損等(deng)諸多(duo)優點，越來越廣泛地應用。但目(mu)前(qian)市場上電(dian)(dian)(dian)子(zi)式(shi)電(dian)(dian)(dian)能表(biao)廠家(jia)繁(fan)多(duo)，質量參差(cha)不(bu)(bu)(bu)(bu)齊，選擇不(bu)(bu)(bu)(bu)好(hao)，不(bu)(bu)(bu)(bu)僅不(bu)(bu)(bu)(bu)能發(fa)揮電(dian)(dian)(dian)子(zi)式(shi)電(dian)(dian)(dian)能表(biao)的優點，反(fan)而(er)會帶來不(bu)(bu)(bu)(bu)應有的損失和增加維護管理(li)的工作量。

電(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)與(yu)我們熟悉(xi)的(de)(de)感(gan)應(ying)(ying)式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)(俗稱機(ji)械(xie)表(biao)(biao))，既有(you)相同的(de)(de)地(di)(di)方(fang)(fang)，也有(you)不相同的(de)(de)地(di)(di)方(fang)(fang)，且不同的(de)(de)地(di)(di)方(fang)(fang)更多，特(te)別是表(biao)(biao)的(de)(de)內部，感(gan)應(ying)(ying)式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)是采用電(dian)(dian)磁(ci)感(gan)應(ying)(ying)元(yuan)件，里(li)面是鐵芯(xin)、鐵圈加機(ji)械(xie)傳動裝置；而(er)電(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)則主要是采用電(dian)(dian)子元(yuan)件，即：電(dian)(dian)阻、電(dian)(dian)容加集成電(dian)(dian)路等。因此，應(ying)(ying)根據電(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)的(de)(de)這一特(te)性(xing)來進(jin)行選擇(ze)(ze)。換句話說(shuo)要以(yi)電(dian)(dian)子設(she)備的(de)(de)技(ji)術(shu)要求進(jin)行選擇(ze)(ze)，而(er)不能(neng)(neng)簡(jian)單(dan)(dan)的(de)(de)照搬以(yi)前選用機(ji)械(xie)式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)的(de)(de)技(ji)術(shu)要求選擇(ze)(ze)電(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)(當然，也有(you)可(ke)以(yi)借鑒的(de)(de)地(di)(di)方(fang)(fang))。現就我們在(zai)工作中體會(hui)，談(tan)談(tan)單(dan)(dan)相電(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)能(neng)(neng)表(biao)(biao)的(de)(de)選購，供(gong)有(you)關的(de)(de)工作人員參考。

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)表(biao)在安(an)裝運行一(yi)段時(shi)間(jian)(jian)(jian)后，必須(xu)進(jin)行抽(chou)(chou)(chou)查(cha)。抽(chou)(chou)(chou)查(cha)的(de)(de)時(shi)間(jian)(jian)(jian)間(jian)(jian)(jian)隔和抽(chou)(chou)(chou)查(cha)比例可以根據(ju)運行中電(dian)能(neng)表(biao)的(de)(de)質(zhi)量(liang)情(qing)(qing)況而定。同一(yi)廠(chang)家(jia)同一(yi)批次的(de)(de)電(dian)能(neng)表(biao)，故障率(lv)小、誤差(cha)變化(hua)小、合格率(lv)高(gao)的(de)(de)可以減少抽(chou)(chou)(chou)查(cha)比例和抽(chou)(chou)(chou)查(cha)時(shi)間(jian)(jian)(jian)間(jian)(jian)(jian)隔。一(yi)般情(qing)(qing)況下，首次選(xuan)(xuan)用的(de)(de)廠(chang)家(jia)產品半年(nian)內抽(chou)(chou)(chou)查(cha)率(lv)不能(neng)少于(yu)5%。一(yi)年(nian)內抽(chou)(chou)(chou)查(cha)比率(lv)不能(neng)少于(yu)10%。如(ru)果質(zhi)量(liang)穩定，誤差(cha)變化(hua)小，則(ze)可以減少抽(chou)(chou)(chou)查(cha)比例，但每年(nian)至少要抽(chou)(chou)(chou)檢1%，以監(jian)(jian)測電(dian)能(neng)表(biao)質(zhi)量(liang)隨時(shi)間(jian)(jian)(jian)變化(hua)情(qing)(qing)況。把電(dian)能(neng)表(biao)的(de)(de)選(xuan)(xuan)購(gou)從事前選(xuan)(xuan)擇延伸(shen)到整個使(shi)用過(guo)程之中，通(tong)過(guo)監(jian)(jian)控使(shi)用中的(de)(de)情(qing)(qing)況，進(jin)一(yi)步(bu)提高(gao)選(xuan)(xuan)購(gou)水平。

查驗生產廠家所必須具備的基本技術條件

電(dian)(dian)能(neng)(neng)表(biao)(biao)是屬國家強制檢(jian)驗(yan)(yan)計(ji)量(liang)器(qi)具(ju)，根據計(ji)量(liang)法規定，所選電(dian)(dian)能(neng)(neng)表(biao)(biao)必(bi)須(xu)具(ju)有(you)省級以上技術(shu)監督局(ju)頒發(fa)的(de)(de)制造(zao)(zao)計(ji)量(liang)器(qi)具(ju)許可證(zheng)(CMC證(zheng))。這(zhe)(zhe)是電(dian)(dian)能(neng)(neng)表(biao)(biao)生(sheng)(sheng)產(chan)(chan)廠(chang)家所必(bi)須(xu)具(ju)備(bei)的(de)(de)條件(jian)和必(bi)須(xu)履行的(de)(de)法律手續。它可以證(zheng)明廠(chang)家具(ju)備(bei)了基本的(de)(de)設(she)施(shi)、人(ren)員和檢(jian)測儀(yi)器(qi)設(she)備(bei)，是可以生(sheng)(sheng)產(chan)(chan)銷(xiao)售(shou)的(de)(de)產(chan)(chan)品。但是在(zai)目前市(shi)場競爭激烈的(de)(de)情(qing)況下，供電(dian)(dian)企業有(you)更大的(de)(de)選擇(ze)余地，因此，還可以多比較一下其他證(zheng)明產(chan)(chan)品質(zhi)量(liang)的(de)(de)文件(jian)。如：權(quan)威部門的(de)(de)鑒定報(bao)告(gao)、壽命試驗(yan)(yan)報(bao)告(gao)、被列入國家經貿委“全國城鄉電(dian)(dian)網建設(she)與改(gai)造(zao)(zao)所需設(she)備(bei)產(chan)(chan)品及生(sheng)(sheng)產(chan)(chan)企業推薦目錄”、ISO9000質(zhi)量(liang)認證(zheng)等(deng)等(deng)。這(zhe)(zhe)些都(dou)是證(zheng)明產(chan)(chan)品質(zhi)量(liang)的(de)(de)重(zhong)要(yao)文件(jian)。

對電能表實物進行檢驗

對廠家送來的(de)電(dian)能表實(shi)物進行檢驗(yan)，主要(yao)是(shi)從以下(xia)(xia)幾(ji)個(ge)(ge)方面(mian)進行。即：機械要(yao)求(qiu)、所能適應的(de)氣(qi)候條件、電(dian)氣(qi)要(yao)求(qiu)、電(dian)磁兼容性、準確(que)度要(yao)求(qiu)這五個(ge)(ge)方面(mian)。這五個(ge)(ge)方面(mian)在國(guo)家標(biao)準《1級(ji)和2級(ji)靜止式交流有(you)(you)功電(dian)能表》(GB/T17215-1998)中都有(you)(you)明(ming)確(que)的(de)規定。規定中有(you)(you)些試驗(yan)和檢驗(yan)項(xiang)目一(yi)般地市級(ji)及縣級(ji)供電(dian)企業有(you)(you)條件檢驗(yan)，但有(you)(you)相當多的(de)項(xiang)目還不具備(bei)條件檢驗(yan)。下(xia)(xia)面(mian)將需要(yao)注(zhu)意的(de)地方和解決的(de)辦(ban)法(fa)做一(yi)簡(jian)要(yao)說明(ming)。

(1)準確度要求：

準(zhun)(zhun)確(que)度要求包括，電(dian)(dian)(dian)流(liu)及(ji)功率因數改變(bian)、電(dian)(dian)(dian)壓(ya)改變(bian)、頻率改變(bian)、起動(dong)(dong)試驗(yan)、潛力(li)試驗(yan)、走(zou)字(zi)試驗(yan)等這些項目的(de)(de)檢(jian)驗(yan)一(yi)(yi)般地市(shi)級及(ji)縣級供電(dian)(dian)(dian)企(qi)業都能(neng)(neng)進行檢(jian)驗(yan)。電(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)能(neng)(neng)表(biao)在規程規定的(de)(de)負載(zai)范圍內(nei)，一(yi)(yi)般線(xian)性度都比(bi)較好，但(dan)不(bu)同廠(chang)家(jia)的(de)(de)表(biao)實(shi)際準(zhun)(zhun)確(que)計量的(de)(de)負載(zai)范圍有(you)很大(da)差別，由于現場實(shi)際負載(zai)電(dian)(dian)(dian)流(liu)是經常(chang)變(bian)化的(de)(de)，能(neng)(neng)準(zhun)(zhun)確(que)計量的(de)(de)負載(zai)范圍越(yue)寬，表(biao)的(de)(de)負載(zai)性能(neng)(neng)越(yue)好。在農村有(you)些地區電(dian)(dian)(dian)網電(dian)(dian)(dian)壓(ya)波(bo)動(dong)(dong)比(bi)較大(da)。要注意檢(jian)查電(dian)(dian)(dian)壓(ya)波(bo)動(dong)(dong)極限情況(kuang)下(xia)，電(dian)(dian)(dian)能(neng)(neng)表(biao)的(de)(de)誤差。特(te)別是低電(dian)(dian)(dian)壓(ya)時的(de)(de)輕載(zai)誤差和電(dian)(dian)(dian)能(neng)(neng)表(biao)走(zou)字(zi)是否有(you)力(li)，檢(jian)查表(biao)內(nei)直流(liu)電(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)壓(ya)不(bu)能(neng)(neng)下(xia)降到計量器(qi)及(ji)芯片的(de)(de)工作電(dian)(dian)(dian)壓(ya)以(yi)下(xia)，直流(liu)電(dian)(dian)(dian)源(yuan)的(de)(de)波(bo)紋不(bu)能(neng)(neng)有(you)明顯(xian)地增(zeng)加，中(zhong)儀電(dian)(dian)(dian)子(zi)生(sheng)產(chan)的(de)(de)單(dan)相電(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)能(neng)(neng)表(biao)及(ji)三相電(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)能(neng)(neng)表(biao)質保一(yi)(yi)年，讓您用的(de)(de)放心(xin)。

準確度要求(qiu)還包括，如諧波、外部磁(ci)感應、高頻電(dian)磁(ci)場影響(xiang)等。一般地市級(ji)及縣級(ji)供電(dian)企(qi)業不具(ju)備條件檢(jian)驗，可以(yi)請省(sheng)級(ji)電(dian)力試驗所(suo)檢(jian)驗。

(2)氣候條件和電磁兼容性能：

這(zhe)兩項對(dui)電(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)電(dian)(dian)(dian)(dian)能(neng)(neng)(neng)來說都很重(zhong)要(yao)。尤其是電(dian)(dian)(dian)(dian)磁兼(jian)容(rong)性能(neng)(neng)(neng)對(dui)電(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)電(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)影響極為嚴重(zhong)，電(dian)(dian)(dian)(dian)磁兼(jian)容(rong)性能(neng)(neng)(neng)較差的(de)(de)表(biao)(biao)，現(xian)場(chang)運行(xing)中往往出現(xian)“死機(ji)”、“飛(fei)字”等現(xian)象，甚至(zhi)內(nei)部電(dian)(dian)(dian)(dian)子(zi)(zi)元件損壞。這(zhe)是電(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)電(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)有別于(yu)機(ji)械式(shi)電(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)的(de)(de)一個(ge)重(zhong)要(yao)特性。電(dian)(dian)(dian)(dian)磁兼(jian)容(rong)檢驗(yan)(yan)(yan)一共有5個(ge)項目，即：靜(jing)電(dian)(dian)(dian)(dian)放電(dian)(dian)(dian)(dian)試驗(yan)(yan)(yan)、高頻電(dian)(dian)(dian)(dian)磁場(chang)試驗(yan)(yan)(yan)、電(dian)(dian)(dian)(dian)快速瞬(shun)變脈(mo)沖(chong)群試驗(yan)(yan)(yan)、浪涌(yong)試驗(yan)(yan)(yan)、無(wu)線電(dian)(dian)(dian)(dian)干(gan)擾抑制試驗(yan)(yan)(yan)。其中浪涌(yong)和脈(mo)沖(chong)群比(bi)較接近電(dian)(dian)(dian)(dian)網(wang)中的(de)(de)一些瞬(shun)態情況(kuang)，建議有條件的(de)(de)地市(shi)級及縣級供電(dian)(dian)(dian)(dian)企業購置相應設備，對(dui)電(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)進(jin)行(xing)抽(chou)查檢驗(yan)(yan)(yan)。

(3)電氣要求：

電(dian)氣(qi)要求的功率消(xiao)耗檢(jian)驗，包(bao)括電(dian)壓線路和電(dian)流(liu)(liu)線路，可以用(yong)互感器校驗儀(yi)測量電(dian)能(neng)表(biao)的電(dian)壓、電(dian)流(liu)(liu)和負載阻抗后，計(ji)算出額(e)定電(dian)壓、額(e)定電(dian)流(liu)(liu)下(xia)電(dian)能(neng)表(biao)的功率消(xiao)耗。這種方法既準(zhun)確(que)又方便；電(dian)源影(ying)響、電(dian)壓降(jiang)落和短(duan)時中斷、自熱影(ying)響可以在電(dian)能(neng)表(biao)校驗臺上模(mo)擬進(jin)行；短(duan)時過(guo)電(dian)流(liu)(liu)會(hui)影(ying)響檢(jian)驗，嚴(yan)格按規(gui)程定義做比較困難，可以在2倍最大電(dian)流(liu)(liu)下(xia)，逐步延長時間，檢(jian)測電(dian)能(neng)表(biao)的溫(wen)升(電(dian)流(liu)(liu)端子及取(qu)樣電(dian)阻)和誤(wu)差。這可以了解電(dian)能(neng)表(biao)過(guo)負載后的損(sun)壞程度。

為防(fang)止低壓供電(dian)(dian)線路中(zhong)性點斷開(kai)后，因負載不平衡引起某(mou)相電(dian)(dian)壓升高(gao)燒壞(huai)電(dian)(dian)能表(biao)的(de)情況發生，將單相電(dian)(dian)表(biao)的(de)輸入電(dian)(dian)壓升高(gao)到420V，經過4小時(shi)后，再在額定電(dian)(dian)壓下檢(jian)驗電(dian)(dian)能表(biao)應(ying)合(he)格(試驗時(shi)要有人值守，注意安全，發現有異常立即(ji)斷電(dian)(dian)檢(jian)查)。

(4)機械要求：

機械要(yao)求中的(de)絕大(da)部分內容(rong)是可(ke)以(yi)通過直觀(guan)檢查(cha)和(he)簡單的(de)試驗(yan)(yan)方法進行檢驗(yan)(yan)的(de)。如：四防(fang)(防(fang)電擊；防(fang)過高溫度(du)；防(fang)火焰蔓(man)延；防(fang)固體異物、灰塵和(he)水進入)；鉛封方便(bian)可(ke)靠(只(zhi)有破壞鉛封后才(cai)能(neng)(neng)觸及儀(yi)表(biao)(biao)內部部件(jian))；接線(xian)端子應有足夠(gou)的(de)絕緣性能(neng)(neng)和(he)機械強度(du)；表(biao)(biao)殼的(de)結構和(he)裝配應能(neng)(neng)保證(zheng)(zheng)在出現非永久性變(bian)形時(shi)不妨礙儀(yi)表(biao)(biao)正常工作(zuo)；銘牌、接線(xian)圖、端子標(biao)志符合要(yao)求等等。這些要(yao)求都是保證(zheng)(zheng)電能(neng)(neng)表(biao)(biao)安全運行的(de)最基本要(yao)求，是可(ke)以(yi)憑經驗(yan)(yan)觀(guan)察和(he)識別(bie)的(de)。選用(yong)決(jue)不能(neng)(neng)忽視(shi)。特別(bie)端子板(ban)要(yao)選用(yong)阻(zu)燃材料，如選用(yong)注射(she)型酚醛樹脂(zhi)；外殼采用(yong)ABS工程(cheng)塑料時(shi)要(yao)注意檢查(cha)是否阻(zu)燃；外殼不能(neng)(neng)有明顯變(bian)形影(ying)響(xiang)密(mi)封性能(neng)(neng)和(he)內部元件(jian)有明顯的(de)相對位移。

注意事項

另外需要(yao)注意的(de)(de)有(you)，由(you)于目前(qian)電(dian)(dian)子表的(de)(de)機(ji)(ji)械(xie)計量(liang)器(qi)，還沒(mei)有(you)從原理(li)上根本解決卡(ka)字(zi)問(wen)題。主(zhu)要(yao)是通(tong)過選(xuan)擇(ze)制造工藝好的(de)(de)計量(liang)器(qi)和(he)進廠時嚴格(ge)篩(shai)選(xuan)保證電(dian)(dian)能表整機(ji)(ji)質量(liang)。因(yin)此，要(yao)特別(bie)注意計量(liang)器(qi)的(de)(de)質量(liang)。步(bu)進電(dian)(dian)機(ji)(ji)有(you)屏(ping)蔽(bi)可以(yi)防(fang)電(dian)(dian)磁干擾，外殼采用鋁合金支(zhi)架、齒輪精細(xi)、無(wu)毛刺、材(cai)料(liao)不易(yi)變(bian)形、有(you)自潤滑性能、步(bu)進電(dian)(dian)機(ji)(ji)磁性能強、加工精密，都可以(yi)減少卡(ka)字(zi)的(de)(de)問(wen)題。要(yao)注意仔細(xi)檢查(cha)和(he)了解。再就是要(yao)進行走字(zi)檢驗。為更嚴格(ge)地考(kao)核計量(liang)器(qi)質量(liang)，保證安裝到現場的(de)(de)電(dian)(dian)能表在(zai)電(dian)(dian)壓允許范圍(wei)內(nei)都能正確計量(liang)，建議采用本地區電(dian)(dian)網可能出現的(de)(de)最(zui)低(不考(kao)慮暫態)電(dian)(dian)壓進行走字(zi)試驗。