功率表的使用可(ke)分(fen)為三個步驟

1、正確選(xuan)擇(ze)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)的(de)(de)(de)(de)(de)量(liang)(liang)程(cheng)(cheng)。 選(xuan)擇(ze)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)的(de)(de)(de)(de)(de)量(liang)(liang)程(cheng)(cheng)就是(shi)選(xuan)擇(ze)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)中(zhong)的(de)(de)(de)(de)(de)電(dian)(dian)流(liu)量(liang)(liang)程(cheng)(cheng)和電(dian)(dian)壓(ya)(ya)(ya)量(liang)(liang)程(cheng)(cheng)。使(shi)(shi)用時(shi)應使(shi)(shi)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)中(zhong)的(de)(de)(de)(de)(de) 電(dian)(dian)流(liu)表(biao)(biao) 程(cheng)(cheng)不小于(yu)(yu)負(fu)載電(dian)(dian)流(liu)，電(dian)(dian)壓(ya)(ya)(ya)量(liang)(liang)程(cheng)(cheng)不低于(yu)(yu)負(fu)載電(dian)(dian)壓(ya)(ya)(ya)，而不能(neng)僅從功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)量(liang)(liang)程(cheng)(cheng)來考慮。例(li)如(ru)，兩只功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)，量(liang)(liang)程(cheng)(cheng)分(fen)別是(shi)ia、300v和2a、150v，由(you)計算可(ke)知其(qi)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)量(liang)(liang)程(cheng)(cheng)均(jun)為(wei)(wei)30ow，如(ru)果要(yao)測量(liang)(liang)一負(fu)載電(dian)(dian)壓(ya)(ya)(ya)為(wei)(wei)220v、電(dian)(dian)流(liu)為(wei)(wei)ia的(de)(de)(de)(de)(de)負(fu)載功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)時(shi)應逸用ia、300v的(de)(de)(de)(de)(de)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)，而2a、150v的(de)(de)(de)(de)(de)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)雖功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)量(liang)(liang)程(cheng)(cheng)也大于(yu)(yu)負(fu)載功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)，但是(shi)由(you)于(yu)(yu)負(fu)載電(dian)(dian)壓(ya)(ya)(ya)高于(yu)(yu)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)所能(neng)承受的(de)(de)(de)(de)(de)電(dian)(dian)壓(ya)(ya)(ya)150v，故不能(neng)使(shi)(shi)用。所以，在(zai)測量(liang)(liang)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)前要(yao)根(gen)據負(fu)載的(de)(de)(de)(de)(de)額定(ding)電(dian)(dian)壓(ya)(ya)(ya)和額定(ding)電(dian)(dian)流(liu)來選(xuan)擇(ze)功(gong)(gong)(gong)率(lv)(lv)(lv)(lv)表(biao)(biao)的(de)(de)(de)(de)(de)量(liang)(liang)程(cheng)(cheng)。

2、正確連接(jie)測(ce)量線路。 電(dian)(dian)動系測(ce)量機構的(de)(de)轉動力矩方(fang)向和兩線圈(quan)中的(de)(de)電(dian)(dian)流(liu)方(fang)向有關，為了防止電(dian)(dian)動系功率表(biao)的(de)(de)指針反(fan)偏(pian)，接(jie)線時功率表(biao)電(dian)(dian)流(liu)線標有“·"號的(de)(de)端鈕(niu)必須接(jie)到電(dian)(dian)源的(de)(de)正極(ji)，而(er)電(dian)流線(xian)(xian)圈的(de)另(ling)(ling)一(yi)端(duan)(duan)(duan)則與負載(zai)相連，電(dian)流線(xian)(xian)圈以(yi)串聯形式接(jie)入電(dian)路中。功率表電(dian)壓(ya)線(xian)(xian)圈標有“·"號的(de)端(duan)(duan)(duan)鈕可以(yi)接(jie)到(dao)電(dian)源(yuan)端(duan)(duan)(duan)鈕的(de)任(ren)一(yi)端(duan)(duan)(duan)上，而(er)另(ling)(ling)一(yi)電(dian)壓(ya)端(duan)(duan)(duan)鈕則跨(kua)接(jie)到(dao)負載(zai)的(de)另(ling)(ling)一(yi)端(duan)(duan)(duan)。

3、正確讀數。 一般安裝式功率表為直讀單量程式，表上的示數即為功率數。但便攜式功率表一般為多量程式，在表的標度尺上不直接標注示數，只標注分格。在選用不同的電流與電壓量程時，每一分格都可以表示不同的功率數。在讀數時，應先根據所選的電壓量程u、電流量程i以及標度尺滿量程時的格數，求出每格瓦數(又稱功率表常數)c，然后再乘上指針偏轉的格數，就可得到所測功率p。