當把電(dian)(dian)(dian)能(neng)(neng)表(biao)接入被測電(dian)(dian)(dian)路時,電(dian)(dian)(dian)流(liu)(liu)(liu)線圈(quan)和電(dian)(dian)(dian)壓線圈(quan)中(zhong)(zhong)就(jiu)有交變(bian)電(dian)(dian)(dian)流(liu)(liu)(liu)流(liu)(liu)(liu)過(guo),這兩(liang)個交變(bian)電(dian)(dian)(dian)流(liu)(liu)(liu)分別(bie)在(zai)它們(men)的(de)(de)(de)(de)(de)(de)鐵(tie)芯中(zhong)(zhong)產生(sheng)交變(bian)的(de)(de)(de)(de)(de)(de)磁通(tong);交變(bian)磁通(tong)穿(chuan)過(guo)鋁(lv)(lv)盤(pan)(pan)(pan),在(zai)鋁(lv)(lv)盤(pan)(pan)(pan)中(zhong)(zhong)感應出(chu)渦(wo)(wo)流(liu)(liu)(liu);渦(wo)(wo)流(liu)(liu)(liu)又(you)在(zai)磁場(chang)中(zhong)(zhong)受(shou)到力(li)(li)的(de)(de)(de)(de)(de)(de)作用(yong),從而使(shi)(shi)鋁(lv)(lv)盤(pan)(pan)(pan)得到轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)矩(ju)(ju)(主(zhu)動(dong)(dong)(dong)力(li)(li)矩(ju)(ju))而轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)動(dong)(dong)(dong)。負載消(xiao)耗的(de)(de)(de)(de)(de)(de)功(gong)率(lv)(lv)越(yue)大,通(tong)過(guo)電(dian)(dian)(dian)流(liu)(liu)(liu)線圈(quan)的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)流(liu)(liu)(liu)越(yue)大,鋁(lv)(lv)盤(pan)(pan)(pan)中(zhong)(zhong)感應出(chu)的(de)(de)(de)(de)(de)(de)渦(wo)(wo)流(liu)(liu)(liu)也(ye)越(yue)大,使(shi)(shi)鋁(lv)(lv)盤(pan)(pan)(pan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)動(dong)(dong)(dong)的(de)(de)(de)(de)(de)(de)力(li)(li)矩(ju)(ju)就(jiu)越(yue)大。即轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)矩(ju)(ju)的(de)(de)(de)(de)(de)(de)大小(xiao)跟(gen)負載消(xiao)耗的(de)(de)(de)(de)(de)(de)功(gong)率(lv)(lv)成正比(bi)。功(gong)率(lv)(lv)越(yue)大,轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)矩(ju)(ju)也(ye)越(yue)大,鋁(lv)(lv)盤(pan)(pan)(pan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)動(dong)(dong)(dong)也(ye)就(jiu)越(yue)快(kuai)。鋁(lv)(lv)盤(pan)(pan)(pan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)動(dong)(dong)(dong)時,又(you)受(shou)到磁鐵(tie)產生(sheng)的(de)(de)(de)(de)(de)(de)制動(dong)(dong)(dong)力(li)(li)矩(ju)(ju)的(de)(de)(de)(de)(de)(de)作用(yong),制動(dong)(dong)(dong)力(li)(li)矩(ju)(ju)與(yu)主(zhu)動(dong)(dong)(dong)力(li)(li)矩(ju)(ju)方(fang)向相反;制動(dong)(dong)(dong)力(li)(li)矩(ju)(ju)的(de)(de)(de)(de)(de)(de)大小(xiao)與(yu)鋁(lv)(lv)盤(pan)(pan)(pan)的(de)(de)(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)速成正比(bi),鋁(lv)(lv)盤(pan)(pan)(pan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)動(dong)(dong)(dong)得越(yue)快(kuai),制動(dong)(dong)(dong)力(li)(li)矩(ju)(ju)也(ye)越(yue)大。當主(zhu)動(dong)(dong)(dong)力(li)(li)矩(ju)(ju)與(yu)制動(dong)(dong)(dong)力(li)(li)矩(ju)(ju)達到暫時平衡(heng)時,鋁(lv)(lv)盤(pan)(pan)(pan)將(jiang)勻速轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)動(dong)(dong)(dong)。負載所(suo)消(xiao)耗的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)能(neng)(neng)與(yu)鋁(lv)(lv)盤(pan)(pan)(pan)的(de)(de)(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)數成正比(bi)。鋁(lv)(lv)盤(pan)(pan)(pan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)動(dong)(dong)(dong)時,帶動(dong)(dong)(dong)計數器,把所(suo)消(xiao)耗的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)能(neng)(neng)指示出(chu)來。這就(jiu)是電(dian)(dian)(dian)能(neng)(neng)表(biao)工作的(de)(de)(de)(de)(de)(de)簡單(dan)過(guo)程。 [3]
(2)寬量程電能表。近年來,由于居民生活水平的提高,裝設的家用電器日益增多,容量很大,但同時使用的可能性較小。如果選用舊式的單量程電能表,額定電流選擇偏大,在實際負荷很小時,運行電流可能低于電能表額定電流的10*而使計量不準;反之若電能表額定電流選擇偏小,一旦家用電器同時使用,電能表就可能因過負載而燒毀。而寬量程電能表就能克服以上問題,只要所使用家用電器的電流總和在電能表的額定電流范圍之
內(nei),都(dou)可(ke)以**準確(que)的(de)計量(liang)。因此農網(wang)和城網(wang)改造中居民安裝(zhuang)的(de)電(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)一(yi)(yi)般(ban)(ban)為長壽命、寬(kuan)量(liang)程(cheng)電(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)。寬(kuan)量(liang)程(cheng)電(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)又叫高過(guo)載(zai)(zai)倍(bei)數電(dian)能(neng)(neng)(neng)(neng)(neng)表(biao),其過(guo)載(zai)(zai)能(neng)(neng)(neng)(neng)(neng)力(li)可(ke)達2~4倍(bei)。即這種電(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)的(de)額定電(dian)流并非一(yi)(yi)個固定值,而(er)是一(yi)(yi)個彈(dan)性(xing)范(fan)圍。如單相(xiang)表(biao)銘(ming)牌標有(you)(you):2.0級,220V,10(40)A,則說明該表(biao)過(guo)載(zai)(zai)能(neng)(neng)(neng)(neng)(neng)力(li)為4倍(bei);電(dian)能(neng)(neng)(neng)(neng)(neng)表(biao)的(de)額定電(dian)流在(zai)10~40A以內(nei)時,準確(que)性(xing)仍能(neng)(neng)(neng)(neng)(neng)滿足2.0級的(de)要求。而(er)2.0級,220V,10A的(de)普通電(dian)能(neng)(neng)(neng)(neng)(neng)表(biao),其過(guo)載(zai)(zai)能(neng)(neng)(neng)(neng)(neng)力(li)一(yi)(yi)般(ban)(ban)只有(you)(you)1.5~2倍(bei)。