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)子式(shi)電(dian)(dian)能(neng)表比感(gan)應(ying)式(shi)電(dian)(dian)能(neng)表準確度高、功耗低、起動電(dian)(dian)流小、負(fu)載范圍寬、無機械磨損等諸多(duo)優點(dian)，越來越廣(guang)泛地應(ying)用。但(dan)目前市場上電(dian)(dian)子式(shi)電(dian)(dian)能(neng)表廠家繁多(duo)，質量(liang)(liang)參(can)差不齊(qi)，選擇不好(hao)，不僅不能(neng)發揮電(dian)(dian)子式(shi)電(dian)(dian)能(neng)表的(de)優點(dian)，反而會帶來不應(ying)有的(de)損失和增加維(wei)護管理的(de)工作量(liang)(liang)。

電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)與我們(men)(men)熟(shu)悉(xi)的(de)(de)感(gan)應式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(俗稱機械表(biao))，既(ji)有相(xiang)同的(de)(de)地(di)方(fang)(fang)，也有不相(xiang)同的(de)(de)地(di)方(fang)(fang)，且不同的(de)(de)地(di)方(fang)(fang)更多，特別是(shi)表(biao)的(de)(de)內部，感(gan)應式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)是(shi)采(cai)用(yong)電(dian)(dian)(dian)(dian)(dian)磁(ci)感(gan)應元件，里面是(shi)鐵芯、鐵圈加(jia)機械傳動(dong)裝置；而(er)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)則主(zhu)要是(shi)采(cai)用(yong)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(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)(zi)(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)的(de)(de)這(zhe)一特性來進行(xing)選(xuan)(xuan)擇(ze)。換句話說要以(yi)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)設備的(de)(de)技術(shu)要求進行(xing)選(xuan)(xuan)擇(ze)，而(er)不能(neng)(neng)簡單的(de)(de)照搬以(yi)前選(xuan)(xuan)用(yong)機械式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)的(de)(de)技術(shu)要求選(xuan)(xuan)擇(ze)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)(當然，也有可以(yi)借鑒(jian)的(de)(de)地(di)方(fang)(fang))。現(xian)就(jiu)我們(men)(men)在工(gong)(gong)作(zuo)中體會，談談單相(xiang)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)的(de)(de)選(xuan)(xuan)購，供(gong)有關的(de)(de)工(gong)(gong)作(zuo)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(zhuang)運(yun)行一段時(shi)(shi)(shi)間(jian)后，必須進行抽(chou)查(cha)(cha)。抽(chou)查(cha)(cha)的(de)(de)時(shi)(shi)(shi)間(jian)間(jian)隔和(he)抽(chou)查(cha)(cha)比(bi)例(li)可以根據運(yun)行中電能(neng)(neng)(neng)表(biao)的(de)(de)質(zhi)量(liang)(liang)情(qing)(qing)況而定(ding)。同一廠家同一批次的(de)(de)電能(neng)(neng)(neng)表(biao)，故障率(lv)小(xiao)、誤(wu)差變(bian)化(hua)(hua)小(xiao)、合(he)格率(lv)高的(de)(de)可以減少(shao)抽(chou)查(cha)(cha)比(bi)例(li)和(he)抽(chou)查(cha)(cha)時(shi)(shi)(shi)間(jian)間(jian)隔。一般(ban)情(qing)(qing)況下，首次選(xuan)(xuan)用(yong)(yong)的(de)(de)廠家產品(pin)半年(nian)內抽(chou)查(cha)(cha)率(lv)不能(neng)(neng)(neng)少(shao)于(yu)5%。一年(nian)內抽(chou)查(cha)(cha)比(bi)率(lv)不能(neng)(neng)(neng)少(shao)于(yu)10%。如(ru)果質(zhi)量(liang)(liang)穩定(ding)，誤(wu)差變(bian)化(hua)(hua)小(xiao)，則可以減少(shao)抽(chou)查(cha)(cha)比(bi)例(li)，但每年(nian)至少(shao)要抽(chou)檢1%，以監測電能(neng)(neng)(neng)表(biao)質(zhi)量(liang)(liang)隨(sui)時(shi)(shi)(shi)間(jian)變(bian)化(hua)(hua)情(qing)(qing)況。把(ba)電能(neng)(neng)(neng)表(biao)的(de)(de)選(xuan)(xuan)購(gou)從事(shi)前選(xuan)(xuan)擇延伸到整個(ge)使用(yong)(yong)過(guo)(guo)程之中，通過(guo)(guo)監控使用(yong)(yong)中的(de)(de)情(qing)(qing)況，進一步提高選(xuan)(xuan)購(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(neng)表(biao)是(shi)(shi)屬國家強制(zhi)檢驗計(ji)(ji)量(liang)器(qi)具，根據計(ji)(ji)量(liang)法規定，所選(xuan)電(dian)能(neng)表(biao)必須(xu)具有(you)(you)省級以(yi)上技術監督局頒發的(de)(de)制(zhi)造計(ji)(ji)量(liang)器(qi)具許可(ke)(ke)證(zheng)(CMC證(zheng))。這是(shi)(shi)電(dian)能(neng)表(biao)生產(chan)(chan)(chan)廠(chang)家所必須(xu)具備的(de)(de)條件(jian)和必須(xu)履(lv)行的(de)(de)法律手(shou)續。它可(ke)(ke)以(yi)證(zheng)明廠(chang)家具備了基本(ben)的(de)(de)設施、人(ren)員(yuan)和檢測(ce)儀器(qi)設備，是(shi)(shi)可(ke)(ke)以(yi)生產(chan)(chan)(chan)銷售的(de)(de)產(chan)(chan)(chan)品(pin)。但是(shi)(shi)在(zai)目前市(shi)場競爭激烈(lie)的(de)(de)情況下(xia)，供電(dian)企(qi)(qi)業有(you)(you)更大的(de)(de)選(xuan)擇余地(di)，因此，還可(ke)(ke)以(yi)多比較一下(xia)其他證(zheng)明產(chan)(chan)(chan)品(pin)質(zhi)(zhi)量(liang)的(de)(de)文件(jian)。如(ru)：權(quan)威部門的(de)(de)鑒定報(bao)告、壽命(ming)試(shi)驗報(bao)告、被列入國家經貿委“全國城鄉電(dian)網建設與改(gai)造所需(xu)設備產(chan)(chan)(chan)品(pin)及生產(chan)(chan)(chan)企(qi)(qi)業推薦(jian)目錄”、ISO9000質(zhi)(zhi)量(liang)認證(zheng)等等。這些都是(shi)(shi)證(zheng)明產(chan)(chan)(chan)品(pin)質(zhi)(zhi)量(liang)的(de)(de)重要(yao)文件(jian)。

對電能表實物進行檢驗

對廠家(jia)送(song)來的(de)(de)(de)電(dian)能表實物進行檢驗(yan)(yan)(yan)，主(zhu)要(yao)是從以下(xia)幾個方(fang)(fang)面(mian)(mian)進行。即(ji)：機(ji)械要(yao)求(qiu)、所能適應(ying)的(de)(de)(de)氣候條件(jian)、電(dian)氣要(yao)求(qiu)、電(dian)磁兼容性、準確(que)度要(yao)求(qiu)這五個方(fang)(fang)面(mian)(mian)。這五個方(fang)(fang)面(mian)(mian)在國家(jia)標準《1級(ji)(ji)和2級(ji)(ji)靜止式交流有(you)功電(dian)能表》(GB/T17215-1998)中都有(you)明確(que)的(de)(de)(de)規定(ding)(ding)。規定(ding)(ding)中有(you)些試驗(yan)(yan)(yan)和檢驗(yan)(yan)(yan)項(xiang)目一(yi)般地市級(ji)(ji)及縣級(ji)(ji)供(gong)電(dian)企業(ye)有(you)條件(jian)檢驗(yan)(yan)(yan)，但(dan)有(you)相當多的(de)(de)(de)項(xiang)目還不具備條件(jian)檢驗(yan)(yan)(yan)。下(xia)面(mian)(mian)將需要(yao)注(zhu)意的(de)(de)(de)地方(fang)(fang)和解決的(de)(de)(de)辦法做一(yi)簡要(yao)說明。

(1)準確度要求：

準(zhun)確度(du)要(yao)求包(bao)括，電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)及功率因(yin)數改變(bian)、電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)改變(bian)、頻率改變(bian)、起動(dong)試(shi)驗(yan)(yan)(yan)(yan)、潛力試(shi)驗(yan)(yan)(yan)(yan)、走字試(shi)驗(yan)(yan)(yan)(yan)等這些(xie)項目的(de)(de)(de)(de)(de)檢(jian)驗(yan)(yan)(yan)(yan)一般地(di)(di)市級及縣級供電(dian)(dian)(dian)(dian)(dian)企業都(dou)能(neng)進行檢(jian)驗(yan)(yan)(yan)(yan)。電(dian)(dian)(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)在規程規定的(de)(de)(de)(de)(de)負載(zai)(zai)范圍(wei)內，一般線性(xing)度(du)都(dou)比(bi)較好，但(dan)不(bu)(bu)(bu)同廠家的(de)(de)(de)(de)(de)表(biao)實際準(zhun)確計量的(de)(de)(de)(de)(de)負載(zai)(zai)范圍(wei)有(you)(you)很大差(cha)(cha)別，由于現(xian)場實際負載(zai)(zai)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)是經常變(bian)化的(de)(de)(de)(de)(de)，能(neng)準(zhun)確計量的(de)(de)(de)(de)(de)負載(zai)(zai)范圍(wei)越(yue)寬，表(biao)的(de)(de)(de)(de)(de)負載(zai)(zai)性(xing)能(neng)越(yue)好。在農村有(you)(you)些(xie)地(di)(di)區電(dian)(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)波(bo)動(dong)比(bi)較大。要(yao)注意檢(jian)查(cha)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)波(bo)動(dong)極限(xian)情況下(xia)，電(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)的(de)(de)(de)(de)(de)誤差(cha)(cha)。特(te)別是低(di)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)時的(de)(de)(de)(de)(de)輕載(zai)(zai)誤差(cha)(cha)和電(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)走字是否有(you)(you)力，檢(jian)查(cha)表(biao)內直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)能(neng)下(xia)降到計量器(qi)及芯(xin)片的(de)(de)(de)(de)(de)工作電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)以下(xia)，直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)(de)(de)波(bo)紋(wen)不(bu)(bu)(bu)能(neng)有(you)(you)明顯(xian)地(di)(di)增加，中儀電(dian)(dian)(dian)(dian)(dian)子(zi)生產的(de)(de)(de)(de)(de)單相(xiang)電(dian)(dian)(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)及三(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)子(zi)式電(dian)(dian)(dian)(dian)(dian)能(neng)表(biao)質(zhi)保一年，讓您用的(de)(de)(de)(de)(de)放心。

準確度要(yao)求還包括(kuo)，如諧波、外部磁感應、高頻電磁場影響等。一般(ban)地市級(ji)及縣(xian)級(ji)供電企業不具(ju)備條件檢驗，可以(yi)請省級(ji)電力試(shi)驗所檢驗。

(2)氣候條件和電磁兼容性能：

這兩項對(dui)電(dian)子式(shi)(shi)電(dian)能(neng)來說(shuo)都很重要(yao)。尤其是(shi)(shi)電(dian)磁兼(jian)容性(xing)能(neng)對(dui)電(dian)子式(shi)(shi)電(dian)能(neng)表影(ying)響(xiang)極為嚴重，電(dian)磁兼(jian)容性(xing)能(neng)較(jiao)差的(de)表，現場運行(xing)中(zhong)往往出現“死機(ji)”、“飛字”等(deng)現象，甚至內(nei)部電(dian)子元件損壞。這是(shi)(shi)電(dian)子式(shi)(shi)電(dian)能(neng)表有(you)(you)別于機(ji)械式(shi)(shi)電(dian)能(neng)表的(de)一個重要(yao)特性(xing)。電(dian)磁兼(jian)容檢(jian)驗(yan)(yan)一共有(you)(you)5個項目，即：靜(jing)電(dian)放電(dian)試(shi)(shi)(shi)驗(yan)(yan)、高頻電(dian)磁場試(shi)(shi)(shi)驗(yan)(yan)、電(dian)快速瞬(shun)變脈沖群試(shi)(shi)(shi)驗(yan)(yan)、浪涌試(shi)(shi)(shi)驗(yan)(yan)、無線電(dian)干擾抑制(zhi)試(shi)(shi)(shi)驗(yan)(yan)。其中(zhong)浪涌和脈沖群比較(jiao)接近電(dian)網中(zhong)的(de)一些瞬(shun)態情況，建議有(you)(you)條(tiao)件的(de)地市(shi)級及縣級供(gong)電(dian)企業購置相應設備，對(dui)電(dian)能(neng)表進行(xing)抽查檢(jian)驗(yan)(yan)。

(3)電氣要求：

電(dian)(dian)(dian)氣要求(qiu)的(de)功率消耗(hao)(hao)檢驗(yan)(yan)，包括電(dian)(dian)(dian)壓線(xian)路(lu)和(he)電(dian)(dian)(dian)流線(xian)路(lu)，可以(yi)用互感器校驗(yan)(yan)儀測量電(dian)(dian)(dian)能表的(de)電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流和(he)負載(zai)(zai)阻抗后，計算(suan)出額定電(dian)(dian)(dian)壓、額定電(dian)(dian)(dian)流下電(dian)(dian)(dian)能表的(de)功率消耗(hao)(hao)。這種(zhong)方(fang)法(fa)既準確又方(fang)便；電(dian)(dian)(dian)源影響、電(dian)(dian)(dian)壓降落(luo)和(he)短時中(zhong)斷(duan)、自熱(re)影響可以(yi)在電(dian)(dian)(dian)能表校驗(yan)(yan)臺上(shang)模(mo)擬進行；短時過電(dian)(dian)(dian)流會影響檢驗(yan)(yan)，嚴(yan)格(ge)按規程定義(yi)做(zuo)比較困(kun)難，可以(yi)在2倍(bei)最大電(dian)(dian)(dian)流下，逐步延長時間，檢測電(dian)(dian)(dian)能表的(de)溫升(sheng)(電(dian)(dian)(dian)流端子及取樣(yang)電(dian)(dian)(dian)阻)和(he)誤差(cha)。這可以(yi)了(le)解電(dian)(dian)(dian)能表過負載(zai)(zai)后的(de)損壞程度。

為(wei)防止低壓(ya)供電(dian)線路中性點斷(duan)開后，因負載不(bu)平衡引(yin)起某相(xiang)電(dian)壓(ya)升(sheng)高燒壞電(dian)能表(biao)(biao)(biao)的情況發(fa)生(sheng)，將單相(xiang)電(dian)表(biao)(biao)(biao)的輸入電(dian)壓(ya)升(sheng)高到(dao)420V，經過(guo)4小時(shi)后，再在額定電(dian)壓(ya)下檢(jian)(jian)驗(yan)電(dian)能表(biao)(biao)(biao)應合格(試驗(yan)時(shi)要(yao)有人值守，注意安全，發(fa)現有異常立即斷(duan)電(dian)檢(jian)(jian)查)。

(4)機械要求：

機(ji)械(xie)要(yao)求中的(de)(de)絕大(da)部(bu)(bu)分(fen)內(nei)容是(shi)可(ke)以通過(guo)直觀(guan)檢(jian)(jian)查(cha)和(he)(he)簡單的(de)(de)試驗(yan)方法進行檢(jian)(jian)驗(yan)的(de)(de)。如：四(si)防(fang)(防(fang)電擊；防(fang)過(guo)高溫(wen)度；防(fang)火焰(yan)蔓延；防(fang)固體異物、灰塵(chen)和(he)(he)水進入)；鉛封方便可(ke)靠(只有(you)破(po)壞鉛封后才(cai)能(neng)觸(chu)及儀表(biao)內(nei)部(bu)(bu)部(bu)(bu)件)；接線端子應有(you)足夠的(de)(de)絕緣性能(neng)和(he)(he)機(ji)械(xie)強度；表(biao)殼的(de)(de)結構和(he)(he)裝配應能(neng)保證(zheng)在出現非永久性變形時(shi)不(bu)妨礙儀表(biao)正常工作(zuo)；銘牌、接線圖、端子標志符合要(yao)求等等。這些要(yao)求都(dou)是(shi)保證(zheng)電能(neng)表(biao)安全運行的(de)(de)最基本要(yao)求，是(shi)可(ke)以憑經驗(yan)觀(guan)察和(he)(he)識別的(de)(de)。選(xuan)用決不(bu)能(neng)忽視。特別端子板要(yao)選(xuan)用阻燃材料，如選(xuan)用注射型(xing)酚醛樹脂；外殼采用ABS工程塑料時(shi)要(yao)注意檢(jian)(jian)查(cha)是(shi)否阻燃；外殼不(bu)能(neng)有(you)明顯變形影(ying)響密封性能(neng)和(he)(he)內(nei)部(bu)(bu)元件有(you)明顯的(de)(de)相(xiang)對位移。

注意事項

另外需要(yao)(yao)注意的(de)(de)(de)(de)有(you)，由于目前(qian)電(dian)子表的(de)(de)(de)(de)機(ji)械計(ji)量(liang)器(qi)，還沒有(you)從原理上根本(ben)解決卡字問(wen)題。主要(yao)(yao)是通過選(xuan)擇制造工藝好的(de)(de)(de)(de)計(ji)量(liang)器(qi)和(he)進(jin)廠時嚴格(ge)篩(shai)選(xuan)保證(zheng)電(dian)能(neng)表整(zheng)機(ji)質量(liang)。因此(ci)，要(yao)(yao)特別注意計(ji)量(liang)器(qi)的(de)(de)(de)(de)質量(liang)。步進(jin)電(dian)機(ji)有(you)屏蔽可以(yi)(yi)防電(dian)磁干(gan)擾，外殼采(cai)用(yong)鋁合金(jin)支(zhi)架、齒輪(lun)精細(xi)、無毛刺、材料不易(yi)變形、有(you)自(zi)潤滑性能(neng)、步進(jin)電(dian)機(ji)磁性能(neng)強、加工精密，都(dou)可以(yi)(yi)減少(shao)卡字的(de)(de)(de)(de)問(wen)題。要(yao)(yao)注意仔(zi)細(xi)檢查和(he)了解。再(zai)就是要(yao)(yao)進(jin)行(xing)走字檢驗。為更(geng)嚴格(ge)地(di)(di)考(kao)核計(ji)量(liang)器(qi)質量(liang)，保證(zheng)安裝到現場的(de)(de)(de)(de)電(dian)能(neng)表在電(dian)壓允許范(fan)圍內都(dou)能(neng)正確計(ji)量(liang)，建議采(cai)用(yong)本(ben)地(di)(di)區(qu)電(dian)網可能(neng)出(chu)現的(de)(de)(de)(de)最低(di)(不考(kao)慮暫態)電(dian)壓進(jin)行(xing)走字試(shi)驗。