三相電加熱管

        380伏三(san)(san)相(xiang)四線電(dian)(dian)(dian)路中(zhong)，任意兩根火(huo)線之間的(de)電(dian)(dian)(dian)壓都是380伏，任意一根火(huo)線與零線之間都可以組成220伏。這個系統(tong)可以形成三(san)(san)種(zhong)(zhong)電(dian)(dian)(dian)源(yuan)：即(ji)單相(xiang)220伏電(dian)(dian)(dian)源(yuan)，單相(xiang)380伏電(dian)(dian)(dian)源(yuan)，三(san)(san)相(xiang)380伏電(dian)(dian)(dian)源(yuan)，第 I 種(zhong)(zhong)家用(yong)比較多，第三(san)(san)種(zhong)(zhong)工(gong)廠里電(dian)(dian)(dian)機類用(yong)得(de)多，第二種(zhong)(zhong)用(yong)得(de)少，只有交流電(dian)(dian)(dian)焊機經常用(yong)到單相(xiang)380伏電(dian)(dian)(dian)源(yuan)。