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(zi)式(shi)(shi)電(dian)能(neng)(neng)表比感應式(shi)(shi)電(dian)能(neng)(neng)表準確度高、功耗低、起動電(dian)流小、負載范圍寬、無(wu)機械磨損等諸(zhu)多(duo)(duo)優點(dian)，越(yue)(yue)來越(yue)(yue)廣泛地(di)應用。但目前市場上電(dian)子(zi)式(shi)(shi)電(dian)能(neng)(neng)表廠(chang)家繁(fan)多(duo)(duo)，質量參差不(bu)(bu)齊，選擇不(bu)(bu)好，不(bu)(bu)僅不(bu)(bu)能(neng)(neng)發揮電(dian)子(zi)式(shi)(shi)電(dian)能(neng)(neng)表的(de)(de)優點(dian)，反而會帶(dai)來不(bu)(bu)應有的(de)(de)損失和增加維(wei)護管理的(de)(de)工作(zuo)量。

電(dian)(dian)子式電(dian)(dian)能(neng)表(biao)與我(wo)們熟悉的(de)(de)(de)感應(ying)(ying)式電(dian)(dian)能(neng)表(biao)(俗稱(cheng)機械(xie)(xie)表(biao))，既有(you)相(xiang)同(tong)的(de)(de)(de)地(di)方(fang)，也有(you)不相(xiang)同(tong)的(de)(de)(de)地(di)方(fang)，且不同(tong)的(de)(de)(de)地(di)方(fang)更多，特(te)別(bie)是(shi)表(biao)的(de)(de)(de)內部(bu)，感應(ying)(ying)式電(dian)(dian)能(neng)表(biao)是(shi)采用(yong)電(dian)(dian)磁感應(ying)(ying)元件，里面是(shi)鐵芯、鐵圈加(jia)機械(xie)(xie)傳動裝置(zhi)；而電(dian)(dian)子式電(dian)(dian)能(neng)表(biao)則主要(yao)(yao)是(shi)采用(yong)電(dian)(dian)子元件，即：電(dian)(dian)阻、電(dian)(dian)容加(jia)集成(cheng)電(dian)(dian)路(lu)等。因(yin)此，應(ying)(ying)根據電(dian)(dian)子式電(dian)(dian)能(neng)表(biao)的(de)(de)(de)這(zhe)一(yi)特(te)性來(lai)進行(xing)選(xuan)(xuan)擇(ze)。換句話說要(yao)(yao)以(yi)電(dian)(dian)子設(she)備的(de)(de)(de)技術(shu)要(yao)(yao)求(qiu)(qiu)進行(xing)選(xuan)(xuan)擇(ze)，而不能(neng)簡單(dan)的(de)(de)(de)照搬以(yi)前選(xuan)(xuan)用(yong)機械(xie)(xie)式電(dian)(dian)能(neng)表(biao)的(de)(de)(de)技術(shu)要(yao)(yao)求(qiu)(qiu)選(xuan)(xuan)擇(ze)電(dian)(dian)子式電(dian)(dian)能(neng)表(biao)(當然，也有(you)可以(yi)借鑒(jian)的(de)(de)(de)地(di)方(fang))。現就(jiu)我(wo)們在(zai)工作中體會，談談單(dan)相(xiang)電(dian)(dian)子式電(dian)(dian)能(neng)表(biao)的(de)(de)(de)選(xuan)(xuan)購，供有(you)關的(de)(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)(dian)表(biao)在安裝(zhuang)運行(xing)(xing)一(yi)段時間后(hou)，必須進行(xing)(xing)抽(chou)(chou)查(cha)。抽(chou)(chou)查(cha)的(de)時間間隔(ge)和(he)抽(chou)(chou)查(cha)比例(li)可以(yi)根據運行(xing)(xing)中(zhong)電(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)的(de)質(zhi)量情況(kuang)而定。同一(yi)廠家同一(yi)批次(ci)的(de)電(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)，故障率(lv)小、誤(wu)差(cha)變化小、合(he)格(ge)率(lv)高的(de)可以(yi)減(jian)少(shao)(shao)抽(chou)(chou)查(cha)比例(li)和(he)抽(chou)(chou)查(cha)時間間隔(ge)。一(yi)般(ban)情況(kuang)下，首次(ci)選用(yong)的(de)廠家產品半年內抽(chou)(chou)查(cha)率(lv)不(bu)能(neng)(neng)(neng)少(shao)(shao)于5%。一(yi)年內抽(chou)(chou)查(cha)比率(lv)不(bu)能(neng)(neng)(neng)少(shao)(shao)于10%。如(ru)果質(zhi)量穩定，誤(wu)差(cha)變化小，則可以(yi)減(jian)少(shao)(shao)抽(chou)(chou)查(cha)比例(li)，但每年至少(shao)(shao)要抽(chou)(chou)檢(jian)1%，以(yi)監測電(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)質(zhi)量隨時間變化情況(kuang)。把電(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)的(de)選購從事前選擇延(yan)伸到整(zheng)個(ge)使(shi)用(yong)過(guo)(guo)程(cheng)之中(zhong)，通過(guo)(guo)監控使(shi)用(yong)中(zhong)的(de)情況(kuang)，進一(yi)步(bu)提高選購水(shui)平。

查驗生產廠家所必須具備的基本技術條件

電能表是屬國家強(qiang)制檢驗計(ji)量(liang)(liang)器(qi)(qi)具，根據計(ji)量(liang)(liang)法規定，所選(xuan)電能表必須具有省級以上技術監督局(ju)頒(ban)發的(de)(de)(de)制造(zao)計(ji)量(liang)(liang)器(qi)(qi)具許(xu)可(ke)證(zheng)(CMC證(zheng))。這是電能表生產(chan)廠家所必須具備(bei)(bei)的(de)(de)(de)條件和必須履行的(de)(de)(de)法律手續。它可(ke)以證(zheng)明(ming)廠家具備(bei)(bei)了基本(ben)的(de)(de)(de)設施、人員(yuan)和檢測儀器(qi)(qi)設備(bei)(bei)，是可(ke)以生產(chan)銷售的(de)(de)(de)產(chan)品。但是在目前市(shi)場競爭激烈(lie)的(de)(de)(de)情況(kuang)下，供(gong)電企業有更大的(de)(de)(de)選(xuan)擇(ze)余地，因此(ci)，還可(ke)以多比較一下其他證(zheng)明(ming)產(chan)品質(zhi)量(liang)(liang)的(de)(de)(de)文件。如：權威部門(men)的(de)(de)(de)鑒定報告、壽命試驗報告、被列入(ru)國家經貿委“全國城鄉電網建設與改造(zao)所需設備(bei)(bei)產(chan)品及生產(chan)企業推(tui)薦(jian)目錄”、ISO9000質(zhi)量(liang)(liang)認證(zheng)等等。這些都是證(zheng)明(ming)產(chan)品質(zhi)量(liang)(liang)的(de)(de)(de)重要文件。

對電能表實物進行檢驗

對廠家送來的(de)電(dian)能(neng)表實物進行(xing)(xing)檢(jian)(jian)驗(yan)，主要(yao)(yao)是(shi)從以下幾個方(fang)(fang)面(mian)進行(xing)(xing)。即：機(ji)械要(yao)(yao)求(qiu)、所能(neng)適應的(de)氣候條件、電(dian)氣要(yao)(yao)求(qiu)、電(dian)磁兼(jian)容性、準確(que)度要(yao)(yao)求(qiu)這五個方(fang)(fang)面(mian)。這五個方(fang)(fang)面(mian)在國家標準《1級和(he)2級靜止式(shi)交流有(you)(you)功(gong)電(dian)能(neng)表》(GB/T17215-1998)中(zhong)都有(you)(you)明確(que)的(de)規定。規定中(zhong)有(you)(you)些(xie)試驗(yan)和(he)檢(jian)(jian)驗(yan)項(xiang)目一(yi)般地(di)市級及縣級供電(dian)企業有(you)(you)條件檢(jian)(jian)驗(yan)，但有(you)(you)相當(dang)多的(de)項(xiang)目還不具備條件檢(jian)(jian)驗(yan)。下面(mian)將需(xu)要(yao)(yao)注意的(de)地(di)方(fang)(fang)和(he)解決的(de)辦(ban)法做一(yi)簡要(yao)(yao)說明。

(1)準確度要求：

準(zhun)確(que)度要求包括，電(dian)(dian)(dian)流(liu)(liu)及功率(lv)因數改變(bian)、電(dian)(dian)(dian)壓改變(bian)、頻(pin)率(lv)改變(bian)、起(qi)動試驗(yan)(yan)(yan)、潛力(li)試驗(yan)(yan)(yan)、走字試驗(yan)(yan)(yan)等這些項目的(de)檢(jian)(jian)驗(yan)(yan)(yan)一(yi)(yi)般地市級及縣級供電(dian)(dian)(dian)企業(ye)都能(neng)(neng)(neng)(neng)(neng)進行(xing)檢(jian)(jian)驗(yan)(yan)(yan)。電(dian)(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)在規(gui)程規(gui)定的(de)負(fu)載(zai)范(fan)圍(wei)(wei)內(nei)，一(yi)(yi)般線性度都比較好，但(dan)不(bu)(bu)同(tong)廠家(jia)的(de)表(biao)(biao)(biao)實際準(zhun)確(que)計(ji)量的(de)負(fu)載(zai)范(fan)圍(wei)(wei)有很大(da)差(cha)別，由于現場實際負(fu)載(zai)電(dian)(dian)(dian)流(liu)(liu)是經常變(bian)化的(de)，能(neng)(neng)(neng)(neng)(neng)準(zhun)確(que)計(ji)量的(de)負(fu)載(zai)范(fan)圍(wei)(wei)越(yue)寬(kuan)，表(biao)(biao)(biao)的(de)負(fu)載(zai)性能(neng)(neng)(neng)(neng)(neng)越(yue)好。在農村有些地區電(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)壓波動比較大(da)。要注意(yi)檢(jian)(jian)查(cha)電(dian)(dian)(dian)壓波動極限情(qing)況下(xia)(xia)，電(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)的(de)誤差(cha)。特別是低(di)電(dian)(dian)(dian)壓時的(de)輕載(zai)誤差(cha)和電(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)走字是否有力(li)，檢(jian)(jian)查(cha)表(biao)(biao)(biao)內(nei)直流(liu)(liu)電(dian)(dian)(dian)源電(dian)(dian)(dian)壓不(bu)(bu)能(neng)(neng)(neng)(neng)(neng)下(xia)(xia)降到(dao)計(ji)量器及芯片的(de)工作電(dian)(dian)(dian)壓以下(xia)(xia)，直流(liu)(liu)電(dian)(dian)(dian)源的(de)波紋(wen)不(bu)(bu)能(neng)(neng)(neng)(neng)(neng)有明(ming)顯地增加，中儀電(dian)(dian)(dian)子生產(chan)的(de)單相(xiang)電(dian)(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)及三相(xiang)電(dian)(dian)(dian)子式(shi)(shi)(shi)電(dian)(dian)(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)(biao)(biao)質保一(yi)(yi)年，讓您用的(de)放心(xin)。

準(zhun)確度要求還包括，如(ru)諧波、外部磁(ci)感應、高頻電(dian)(dian)磁(ci)場影(ying)響(xiang)等。一般地市級(ji)及(ji)縣(xian)級(ji)供電(dian)(dian)企(qi)業不具備條件檢驗(yan)，可以請省級(ji)電(dian)(dian)力試驗(yan)所檢驗(yan)。

(2)氣候條件和電磁兼容性能：

這(zhe)兩項對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)來(lai)說都很重(zhong)(zhong)要(yao)。尤(you)其(qi)是電(dian)(dian)(dian)(dian)(dian)(dian)磁兼容(rong)性能(neng)(neng)(neng)對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)(biao)影響極為嚴(yan)重(zhong)(zhong)，電(dian)(dian)(dian)(dian)(dian)(dian)磁兼容(rong)性能(neng)(neng)(neng)較(jiao)差的(de)表(biao)(biao)(biao)，現場(chang)運行中(zhong)(zhong)往往出現“死機”、“飛字(zi)”等現象，甚至(zhi)內部電(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)元(yuan)件損壞。這(zhe)是電(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)(biao)有(you)別(bie)于機械式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)(biao)的(de)一(yi)個重(zhong)(zhong)要(yao)特性。電(dian)(dian)(dian)(dian)(dian)(dian)磁兼容(rong)檢驗(yan)一(yi)共有(you)5個項目，即：靜電(dian)(dian)(dian)(dian)(dian)(dian)放電(dian)(dian)(dian)(dian)(dian)(dian)試驗(yan)、高頻電(dian)(dian)(dian)(dian)(dian)(dian)磁場(chang)試驗(yan)、電(dian)(dian)(dian)(dian)(dian)(dian)快速瞬變脈沖(chong)群試驗(yan)、浪涌試驗(yan)、無(wu)線電(dian)(dian)(dian)(dian)(dian)(dian)干(gan)擾(rao)抑制(zhi)試驗(yan)。其(qi)中(zhong)(zhong)浪涌和脈沖(chong)群比較(jiao)接近(jin)電(dian)(dian)(dian)(dian)(dian)(dian)網中(zhong)(zhong)的(de)一(yi)些瞬態情(qing)況，建議有(you)條件的(de)地(di)市級及縣級供電(dian)(dian)(dian)(dian)(dian)(dian)企業購置相應設備，對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)表(biao)(biao)(biao)進(jin)行抽查檢驗(yan)。

(3)電氣要求：

電(dian)(dian)(dian)(dian)(dian)氣(qi)要求的(de)(de)功(gong)(gong)率(lv)消耗(hao)檢(jian)驗(yan)(yan)，包(bao)括電(dian)(dian)(dian)(dian)(dian)壓線(xian)(xian)路和(he)電(dian)(dian)(dian)(dian)(dian)流(liu)線(xian)(xian)路，可(ke)以(yi)(yi)用互(hu)感器校驗(yan)(yan)儀(yi)測量電(dian)(dian)(dian)(dian)(dian)能表(biao)的(de)(de)電(dian)(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)(dian)流(liu)和(he)負載阻抗后(hou)，計算(suan)出(chu)額定(ding)電(dian)(dian)(dian)(dian)(dian)壓、額定(ding)電(dian)(dian)(dian)(dian)(dian)流(liu)下電(dian)(dian)(dian)(dian)(dian)能表(biao)的(de)(de)功(gong)(gong)率(lv)消耗(hao)。這(zhe)種方(fang)(fang)法(fa)既準(zhun)確又(you)方(fang)(fang)便；電(dian)(dian)(dian)(dian)(dian)源影(ying)響、電(dian)(dian)(dian)(dian)(dian)壓降(jiang)落和(he)短時中斷、自熱影(ying)響可(ke)以(yi)(yi)在電(dian)(dian)(dian)(dian)(dian)能表(biao)校驗(yan)(yan)臺上模擬(ni)進(jin)行(xing)；短時過(guo)電(dian)(dian)(dian)(dian)(dian)流(liu)會影(ying)響檢(jian)驗(yan)(yan)，嚴(yan)格按規程定(ding)義做比較困難，可(ke)以(yi)(yi)在2倍最大電(dian)(dian)(dian)(dian)(dian)流(liu)下，逐步延長時間(jian)，檢(jian)測電(dian)(dian)(dian)(dian)(dian)能表(biao)的(de)(de)溫升(sheng)(電(dian)(dian)(dian)(dian)(dian)流(liu)端子及取樣(yang)電(dian)(dian)(dian)(dian)(dian)阻)和(he)誤差。這(zhe)可(ke)以(yi)(yi)了解電(dian)(dian)(dian)(dian)(dian)能表(biao)過(guo)負載后(hou)的(de)(de)損壞(huai)程度。

為防止(zhi)低壓(ya)供(gong)電(dian)(dian)線(xian)路中性(xing)點(dian)斷(duan)開后，因負載(zai)不平(ping)衡引(yin)起某相電(dian)(dian)壓(ya)升(sheng)(sheng)高燒壞電(dian)(dian)能(neng)(neng)表(biao)(biao)(biao)的(de)情況發(fa)生(sheng)，將單相電(dian)(dian)表(biao)(biao)(biao)的(de)輸入(ru)電(dian)(dian)壓(ya)升(sheng)(sheng)高到420V，經過4小(xiao)時后，再(zai)在(zai)額(e)定電(dian)(dian)壓(ya)下檢(jian)驗電(dian)(dian)能(neng)(neng)表(biao)(biao)(biao)應合格(試驗時要(yao)有人值守(shou)，注意安全，發(fa)現有異常(chang)立即斷(duan)電(dian)(dian)檢(jian)查)。

(4)機械要求：

機械要(yao)求中的(de)(de)(de)絕大部分內容是(shi)可以通過直觀檢查和(he)簡單的(de)(de)(de)試驗方(fang)法進行檢驗的(de)(de)(de)。如(ru)：四(si)防(防電擊；防過高溫度；防火焰蔓(man)延；防固體(ti)異物、灰塵(chen)和(he)水進入(ru))；鉛(qian)封方(fang)便可靠(只(zhi)有破壞鉛(qian)封后才能(neng)觸及儀表內部部件(jian))；接(jie)線端子(zi)(zi)應有足(zu)夠(gou)的(de)(de)(de)絕緣性能(neng)和(he)機械強(qiang)度；表殼的(de)(de)(de)結構(gou)和(he)裝配(pei)應能(neng)保(bao)證在出(chu)現非(fei)永久性變(bian)形時不(bu)(bu)妨礙儀表正常工(gong)作；銘牌、接(jie)線圖、端子(zi)(zi)標志符合要(yao)求等等。這些(xie)要(yao)求都是(shi)保(bao)證電能(neng)表安全運行的(de)(de)(de)最基本要(yao)求，是(shi)可以憑經驗觀察(cha)和(he)識別的(de)(de)(de)。選用(yong)(yong)(yong)決(jue)不(bu)(bu)能(neng)忽視。特別端子(zi)(zi)板(ban)要(yao)選用(yong)(yong)(yong)阻燃(ran)材(cai)料，如(ru)選用(yong)(yong)(yong)注射型酚醛樹(shu)脂；外(wai)殼采用(yong)(yong)(yong)ABS工(gong)程塑料時要(yao)注意檢查是(shi)否阻燃(ran)；外(wai)殼不(bu)(bu)能(neng)有明顯變(bian)形影響密封性能(neng)和(he)內部元件(jian)有明顯的(de)(de)(de)相對位移。

注意事項

另外(wai)需要注(zhu)意的有，由(you)于目前電(dian)(dian)子(zi)表(biao)的機械計(ji)量(liang)器(qi)，還沒有從原理(li)上根本解決(jue)卡字(zi)問題。主(zhu)要是通過(guo)選擇制造工藝好的計(ji)量(liang)器(qi)和進(jin)(jin)廠(chang)時嚴格篩(shai)選保(bao)證電(dian)(dian)能表(biao)整機質(zhi)量(liang)。因此，要特(te)別注(zhu)意計(ji)量(liang)器(qi)的質(zhi)量(liang)。步進(jin)(jin)電(dian)(dian)機有屏蔽可(ke)(ke)以防電(dian)(dian)磁干擾，外(wai)殼(ke)采用(yong)鋁(lv)合金支架、齒輪精細、無毛刺、材料不易(yi)變形(xing)、有自潤滑性(xing)能、步進(jin)(jin)電(dian)(dian)機磁性(xing)能強(qiang)、加工精密，都可(ke)(ke)以減(jian)少(shao)卡字(zi)的問題。要注(zhu)意仔細檢查和了解。再就(jiu)是要進(jin)(jin)行(xing)走(zou)字(zi)檢驗。為(wei)更嚴格地考(kao)(kao)核計(ji)量(liang)器(qi)質(zhi)量(liang)，保(bao)證安裝(zhuang)到現(xian)場的電(dian)(dian)能表(biao)在電(dian)(dian)壓允許范圍內(nei)都能正確計(ji)量(liang)，建(jian)議采用(yong)本地區電(dian)(dian)網可(ke)(ke)能出現(xian)的最(zui)低(不考(kao)(kao)慮暫態)電(dian)(dian)壓進(jin)(jin)行(xing)走(zou)字(zi)試驗。