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)子式(shi)電(dian)(dian)(dian)能(neng)(neng)(neng)表比感(gan)應(ying)式(shi)電(dian)(dian)(dian)能(neng)(neng)(neng)表準確度高、功耗低(di)、起動電(dian)(dian)(dian)流小(xiao)、負載范圍寬、無機械磨損等諸多優點，越(yue)來越(yue)廣泛(fan)地(di)應(ying)用。但目前市場(chang)上電(dian)(dian)(dian)子式(shi)電(dian)(dian)(dian)能(neng)(neng)(neng)表廠家(jia)繁多，質(zhi)量(liang)參差不(bu)(bu)齊，選擇(ze)不(bu)(bu)好，不(bu)(bu)僅(jin)不(bu)(bu)能(neng)(neng)(neng)發揮電(dian)(dian)(dian)子式(shi)電(dian)(dian)(dian)能(neng)(neng)(neng)表的(de)優點，反而會帶(dai)來不(bu)(bu)應(ying)有的(de)損失和(he)增加維護管理的(de)工(gong)作量(liang)。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)與(yu)我們熟悉(xi)的(de)(de)(de)感(gan)(gan)應式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)(俗稱(cheng)機械(xie)表(biao)(biao))，既有相同的(de)(de)(de)地(di)方，也有不相同的(de)(de)(de)地(di)方，且不同的(de)(de)(de)地(di)方更(geng)多，特別是(shi)表(biao)(biao)的(de)(de)(de)內部，感(gan)(gan)應式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)是(shi)采用電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁感(gan)(gan)應元件，里面(mian)是(shi)鐵芯、鐵圈加機械(xie)傳動(dong)裝(zhuang)置(zhi)；而電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)則主要是(shi)采用電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)元件，即：電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容加集成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路等。因此，應根據電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)的(de)(de)(de)這一(yi)特性來進行選(xuan)(xuan)擇(ze)。換句話說(shuo)要以(yi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)設(she)備的(de)(de)(de)技術要求(qiu)進行選(xuan)(xuan)擇(ze)，而不能(neng)(neng)簡單的(de)(de)(de)照搬以(yi)前選(xuan)(xuan)用機械(xie)式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)的(de)(de)(de)技術要求(qiu)選(xuan)(xuan)擇(ze)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)(當(dang)然，也有可以(yi)借(jie)鑒的(de)(de)(de)地(di)方)。現(xian)就我們在(zai)工作中體會，談談單相電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(biao)的(de)(de)(de)選(xuan)(xuan)購(gou)，供(gong)有關的(de)(de)(de)工作人(ren)員參(can)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

電表(biao)在安裝運行(xing)一(yi)段時(shi)間(jian)(jian)后，必須進行(xing)抽(chou)查(cha)(cha)。抽(chou)查(cha)(cha)的(de)時(shi)間(jian)(jian)間(jian)(jian)隔和抽(chou)查(cha)(cha)比例可以(yi)根據運行(xing)中電能(neng)表(biao)的(de)質量(liang)情(qing)(qing)況而定。同一(yi)廠家同一(yi)批次的(de)電能(neng)表(biao)，故障率小(xiao)(xiao)、誤差變化(hua)小(xiao)(xiao)、合格(ge)率高的(de)可以(yi)減少抽(chou)查(cha)(cha)比例和抽(chou)查(cha)(cha)時(shi)間(jian)(jian)間(jian)(jian)隔。一(yi)般情(qing)(qing)況下，首次選用(yong)的(de)廠家產品半年(nian)(nian)內抽(chou)查(cha)(cha)率不(bu)能(neng)少于5%。一(yi)年(nian)(nian)內抽(chou)查(cha)(cha)比率不(bu)能(neng)少于10%。如果質量(liang)穩定，誤差變化(hua)小(xiao)(xiao)，則可以(yi)減少抽(chou)查(cha)(cha)比例，但每年(nian)(nian)至少要(yao)抽(chou)檢1%，以(yi)監(jian)測(ce)電能(neng)表(biao)質量(liang)隨(sui)時(shi)間(jian)(jian)變化(hua)情(qing)(qing)況。把電能(neng)表(biao)的(de)選購(gou)從事(shi)前選擇延伸到整(zheng)個使用(yong)過(guo)程之(zhi)中，通過(guo)監(jian)控使用(yong)中的(de)情(qing)(qing)況，進一(yi)步(bu)提高選購(gou)水(shui)平(ping)。

查驗生產廠家所必須具備的基本技術條件

電(dian)(dian)(dian)能(neng)表是(shi)屬國家強(qiang)制檢驗計量器具(ju)，根據計量法(fa)(fa)規定(ding)，所選電(dian)(dian)(dian)能(neng)表必(bi)須(xu)具(ju)有(you)省級以上(shang)技術監督局頒發的(de)(de)制造計量器具(ju)許(xu)可證(zheng)(zheng)(zheng)(CMC證(zheng)(zheng)(zheng))。這是(shi)電(dian)(dian)(dian)能(neng)表生(sheng)產(chan)(chan)(chan)廠家所必(bi)須(xu)具(ju)備的(de)(de)條件和(he)必(bi)須(xu)履行的(de)(de)法(fa)(fa)律(lv)手續(xu)。它可以證(zheng)(zheng)(zheng)明(ming)廠家具(ju)備了(le)基(ji)本的(de)(de)設(she)施、人員和(he)檢測儀(yi)器設(she)備，是(shi)可以生(sheng)產(chan)(chan)(chan)銷售的(de)(de)產(chan)(chan)(chan)品。但是(shi)在(zai)目(mu)前市場競爭(zheng)激(ji)烈的(de)(de)情況下，供(gong)電(dian)(dian)(dian)企(qi)業有(you)更(geng)大的(de)(de)選擇余地，因此，還可以多(duo)比較一下其他證(zheng)(zheng)(zheng)明(ming)產(chan)(chan)(chan)品質(zhi)量的(de)(de)文件。如：權(quan)威部門的(de)(de)鑒定(ding)報(bao)(bao)告(gao)、壽命試驗報(bao)(bao)告(gao)、被列入(ru)國家經(jing)貿委“全國城鄉電(dian)(dian)(dian)網建設(she)與改造所需設(she)備產(chan)(chan)(chan)品及(ji)生(sheng)產(chan)(chan)(chan)企(qi)業推薦目(mu)錄”、ISO9000質(zhi)量認證(zheng)(zheng)(zheng)等(deng)等(deng)。這些都是(shi)證(zheng)(zheng)(zheng)明(ming)產(chan)(chan)(chan)品質(zhi)量的(de)(de)重要(yao)文件。

對電能表實物進行檢驗

對廠(chang)家送來的(de)電(dian)能(neng)表實物(wu)進行檢(jian)(jian)(jian)驗(yan)，主(zhu)要是從以下(xia)幾個(ge)方面進行。即：機械要求、所能(neng)適(shi)應的(de)氣候條件(jian)、電(dian)氣要求、電(dian)磁兼容性、準確度要求這(zhe)五個(ge)方面。這(zhe)五個(ge)方面在國家標準《1級和2級靜(jing)止式交流有功電(dian)能(neng)表》(GB/T17215-1998)中(zhong)都有明確的(de)規(gui)定。規(gui)定中(zhong)有些試驗(yan)和檢(jian)(jian)(jian)驗(yan)項目(mu)一(yi)般地市級及(ji)縣(xian)級供電(dian)企業有條件(jian)檢(jian)(jian)(jian)驗(yan)，但(dan)有相(xiang)當多的(de)項目(mu)還不具(ju)備條件(jian)檢(jian)(jian)(jian)驗(yan)。下(xia)面將(jiang)需要注意的(de)地方和解決的(de)辦法做一(yi)簡(jian)要說明。

(1)準確度要求：

準(zhun)確度(du)要求包括，電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)及(ji)(ji)(ji)功率因數改(gai)(gai)變、電(dian)(dian)(dian)(dian)(dian)壓改(gai)(gai)變、頻率改(gai)(gai)變、起動試(shi)(shi)驗(yan)、潛力試(shi)(shi)驗(yan)、走字試(shi)(shi)驗(yan)等這些項(xiang)目的(de)(de)(de)(de)檢驗(yan)一般(ban)地市級及(ji)(ji)(ji)縣(xian)級供電(dian)(dian)(dian)(dian)(dian)企業都(dou)能(neng)(neng)(neng)(neng)進行檢驗(yan)。電(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)表(biao)在規(gui)程(cheng)規(gui)定的(de)(de)(de)(de)負(fu)載(zai)(zai)范圍(wei)內(nei)，一般(ban)線性(xing)度(du)都(dou)比較好(hao)(hao)，但不同廠(chang)家的(de)(de)(de)(de)表(biao)實(shi)際準(zhun)確計量(liang)的(de)(de)(de)(de)負(fu)載(zai)(zai)范圍(wei)有(you)(you)很大差別(bie)(bie)，由于(yu)現場實(shi)際負(fu)載(zai)(zai)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)是經常變化的(de)(de)(de)(de)，能(neng)(neng)(neng)(neng)準(zhun)確計量(liang)的(de)(de)(de)(de)負(fu)載(zai)(zai)范圍(wei)越(yue)寬，表(biao)的(de)(de)(de)(de)負(fu)載(zai)(zai)性(xing)能(neng)(neng)(neng)(neng)越(yue)好(hao)(hao)。在農村有(you)(you)些地區電(dian)(dian)(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)(dian)(dian)壓波(bo)動比較大。要注意檢查電(dian)(dian)(dian)(dian)(dian)壓波(bo)動極限情況下(xia)，電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)表(biao)的(de)(de)(de)(de)誤差。特(te)別(bie)(bie)是低電(dian)(dian)(dian)(dian)(dian)壓時的(de)(de)(de)(de)輕載(zai)(zai)誤差和電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)表(biao)走字是否有(you)(you)力，檢查表(biao)內(nei)直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)壓不能(neng)(neng)(neng)(neng)下(xia)降(jiang)到計量(liang)器及(ji)(ji)(ji)芯片的(de)(de)(de)(de)工作電(dian)(dian)(dian)(dian)(dian)壓以(yi)下(xia)，直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)(de)波(bo)紋不能(neng)(neng)(neng)(neng)有(you)(you)明顯地增加，中儀(yi)電(dian)(dian)(dian)(dian)(dian)子(zi)生產的(de)(de)(de)(de)單相電(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)表(biao)及(ji)(ji)(ji)三相電(dian)(dian)(dian)(dian)(dian)子(zi)式(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)表(biao)質保一年，讓您用的(de)(de)(de)(de)放心。

準確度要(yao)求還包括(kuo)，如諧波、外部磁感應、高頻(pin)電磁場影響等(deng)。一(yi)般地(di)市級(ji)及(ji)縣級(ji)供電企業不具備條(tiao)件檢(jian)驗(yan)，可以請省級(ji)電力試驗(yan)所檢(jian)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)子式(shi)電(dian)(dian)(dian)(dian)能來說都(dou)很(hen)重要。尤其是電(dian)(dian)(dian)(dian)磁兼(jian)容(rong)性(xing)能對(dui)電(dian)(dian)(dian)(dian)子式(shi)電(dian)(dian)(dian)(dian)能表影響極(ji)為(wei)嚴重，電(dian)(dian)(dian)(dian)磁兼(jian)容(rong)性(xing)能較(jiao)(jiao)差的表，現(xian)(xian)場運行(xing)(xing)中往往出現(xian)(xian)“死(si)機(ji)”、“飛字”等(deng)現(xian)(xian)象，甚至內部電(dian)(dian)(dian)(dian)子元(yuan)件(jian)損壞。這(zhe)是電(dian)(dian)(dian)(dian)子式(shi)電(dian)(dian)(dian)(dian)能表有別于(yu)機(ji)械(xie)式(shi)電(dian)(dian)(dian)(dian)能表的一個(ge)重要特(te)性(xing)。電(dian)(dian)(dian)(dian)磁兼(jian)容(rong)檢驗(yan)(yan)一共(gong)有5個(ge)項目(mu)，即：靜電(dian)(dian)(dian)(dian)放(fang)電(dian)(dian)(dian)(dian)試(shi)(shi)(shi)驗(yan)(yan)、高頻電(dian)(dian)(dian)(dian)磁場試(shi)(shi)(shi)驗(yan)(yan)、電(dian)(dian)(dian)(dian)快速瞬變脈沖群(qun)試(shi)(shi)(shi)驗(yan)(yan)、浪涌試(shi)(shi)(shi)驗(yan)(yan)、無線電(dian)(dian)(dian)(dian)干擾(rao)抑(yi)制試(shi)(shi)(shi)驗(yan)(yan)。其中浪涌和脈沖群(qun)比(bi)較(jiao)(jiao)接近電(dian)(dian)(dian)(dian)網中的一些瞬態(tai)情況，建(jian)議有條件(jian)的地市級(ji)(ji)及縣級(ji)(ji)供電(dian)(dian)(dian)(dian)企業購置相應設備，對(dui)電(dian)(dian)(dian)(dian)能表進行(xing)(xing)抽查檢驗(yan)(yan)。

(3)電氣要求：

電(dian)(dian)(dian)(dian)(dian)氣要求(qiu)的(de)(de)功率(lv)消耗檢驗(yan)，包括電(dian)(dian)(dian)(dian)(dian)壓(ya)線路和電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)線路，可(ke)以(yi)用互感器校(xiao)驗(yan)儀(yi)測量(liang)電(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)的(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)和負載阻抗后，計算出額定電(dian)(dian)(dian)(dian)(dian)壓(ya)、額定電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)下(xia)電(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)的(de)(de)功率(lv)消耗。這種方(fang)(fang)法(fa)既準確又方(fang)(fang)便(bian)；電(dian)(dian)(dian)(dian)(dian)源(yuan)影響(xiang)、電(dian)(dian)(dian)(dian)(dian)壓(ya)降落和短(duan)時(shi)中斷、自(zi)熱影響(xiang)可(ke)以(yi)在電(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)校(xiao)驗(yan)臺上模擬(ni)進行；短(duan)時(shi)過電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)會影響(xiang)檢驗(yan)，嚴格(ge)按規程定義做比較困難，可(ke)以(yi)在2倍最大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)下(xia)，逐步(bu)延長時(shi)間，檢測電(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)的(de)(de)溫升(電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)端子(zi)及取樣(yang)電(dian)(dian)(dian)(dian)(dian)阻)和誤差。這可(ke)以(yi)了解電(dian)(dian)(dian)(dian)(dian)能表(biao)(biao)過負載后的(de)(de)損壞程度。

為防止(zhi)低壓(ya)供電(dian)(dian)線路(lu)中性點斷(duan)開后，因(yin)負(fu)載不(bu)平衡引起某相(xiang)電(dian)(dian)壓(ya)升高(gao)燒壞(huai)電(dian)(dian)能(neng)表(biao)的(de)情(qing)況發生，將單相(xiang)電(dian)(dian)表(biao)的(de)輸入電(dian)(dian)壓(ya)升高(gao)到(dao)420V，經(jing)過4小時后，再在額定電(dian)(dian)壓(ya)下(xia)檢驗電(dian)(dian)能(neng)表(biao)應合格(試(shi)驗時要(yao)有(you)人值(zhi)守，注(zhu)意安全，發現有(you)異常(chang)立即(ji)斷(duan)電(dian)(dian)檢查(cha))。

(4)機械要求：

機械要求(qiu)中的(de)(de)絕大部(bu)分內(nei)容(rong)是(shi)可以通過(guo)直(zhi)觀(guan)檢查(cha)和(he)簡單的(de)(de)試驗方法進行(xing)檢驗的(de)(de)。如(ru)(ru)：四防(防電擊；防過(guo)高溫(wen)度；防火焰蔓延；防固(gu)體異物、灰塵和(he)水進入)；鉛封方便(bian)可靠(只有(you)破壞(huai)鉛封后才能(neng)觸(chu)及儀(yi)表內(nei)部(bu)部(bu)件)；接線(xian)端子應有(you)足夠的(de)(de)絕緣性能(neng)和(he)機械強度；表殼(ke)的(de)(de)結(jie)構和(he)裝(zhuang)配應能(neng)保證在出現非永久性變形(xing)時不妨礙儀(yi)表正(zheng)常工作；銘牌、接線(xian)圖、端子標(biao)志符合要求(qiu)等等。這(zhe)些(xie)要求(qiu)都(dou)是(shi)保證電能(neng)表安全運(yun)行(xing)的(de)(de)最基本要求(qiu)，是(shi)可以憑經(jing)驗觀(guan)察和(he)識別(bie)的(de)(de)。選(xuan)用(yong)(yong)(yong)決不能(neng)忽視(shi)。特別(bie)端子板要選(xuan)用(yong)(yong)(yong)阻燃(ran)材(cai)料，如(ru)(ru)選(xuan)用(yong)(yong)(yong)注射型酚醛樹脂；外(wai)(wai)殼(ke)采用(yong)(yong)(yong)ABS工程塑(su)料時要注意檢查(cha)是(shi)否阻燃(ran)；外(wai)(wai)殼(ke)不能(neng)有(you)明(ming)顯變形(xing)影(ying)響密封性能(neng)和(he)內(nei)部(bu)元件有(you)明(ming)顯的(de)(de)相對位移。

注意事項

另(ling)外需要(yao)注(zhu)意(yi)的(de)(de)有，由于(yu)目前電(dian)(dian)(dian)子表(biao)的(de)(de)機械(xie)計(ji)量器，還沒有從原理上根本解決(jue)卡(ka)字問題(ti)。主要(yao)是通過選擇制造工藝好的(de)(de)計(ji)量器和(he)進(jin)廠(chang)時(shi)嚴格篩(shai)選保(bao)證電(dian)(dian)(dian)能(neng)(neng)表(biao)整機質(zhi)量。因此(ci)，要(yao)特別注(zhu)意(yi)計(ji)量器的(de)(de)質(zhi)量。步進(jin)電(dian)(dian)(dian)機有屏蔽可(ke)以(yi)防(fang)電(dian)(dian)(dian)磁干(gan)擾，外殼采用鋁合金支架、齒輪(lun)精細、無(wu)毛刺、材料不易變(bian)形(xing)、有自潤滑性能(neng)(neng)、步進(jin)電(dian)(dian)(dian)機磁性能(neng)(neng)強(qiang)、加工精密，都可(ke)以(yi)減少卡(ka)字的(de)(de)問題(ti)。要(yao)注(zhu)意(yi)仔細檢(jian)查(cha)和(he)了(le)解。再就是要(yao)進(jin)行走字檢(jian)驗。為(wei)更(geng)嚴格地考核計(ji)量器質(zhi)量，保(bao)證安裝(zhuang)到現場的(de)(de)電(dian)(dian)(dian)能(neng)(neng)表(biao)在電(dian)(dian)(dian)壓允(yun)許范圍內都能(neng)(neng)正(zheng)確計(ji)量，建議(yi)采用本地區(qu)電(dian)(dian)(dian)網可(ke)能(neng)(neng)出現的(de)(de)最低(不考慮暫態)電(dian)(dian)(dian)壓進(jin)行走字試驗。