三相電加熱管

        380伏三(san)相(xiang)四線(xian)電(dian)(dian)(dian)(dian)(dian)路中，任意(yi)兩根(gen)火線(xian)之間的電(dian)(dian)(dian)(dian)(dian)壓都是380伏，任意(yi)一根(gen)火線(xian)與零線(xian)之間都可以組成(cheng)220伏。這個(ge)系(xi)統可以形(xing)成(cheng)三(san)種電(dian)(dian)(dian)(dian)(dian)源：即單(dan)相(xiang)220伏電(dian)(dian)(dian)(dian)(dian)源，單(dan)相(xiang)380伏電(dian)(dian)(dian)(dian)(dian)源，三(san)相(xiang)380伏電(dian)(dian)(dian)(dian)(dian)源，第(di) I 種家用(yong)比(bi)較(jiao)多，第(di)三(san)種工廠里電(dian)(dian)(dian)(dian)(dian)機(ji)類用(yong)得(de)多，第(di)二種用(yong)得(de)少，只有交流電(dian)(dian)(dian)(dian)(dian)焊機(ji)經常用(yong)到(dao)單(dan)相(xiang)380伏電(dian)(dian)(dian)(dian)(dian)源。