三相電加熱管

        380伏(fu)三(san)相四線(xian)電(dian)(dian)(dian)路中，任意兩根火(huo)(huo)線(xian)之(zhi)間(jian)的電(dian)(dian)(dian)壓都是380伏(fu)，任意一根火(huo)(huo)線(xian)與零線(xian)之(zhi)間(jian)都可以(yi)組成(cheng)220伏(fu)。這個系(xi)統可以(yi)形成(cheng)三(san)種電(dian)(dian)(dian)源(yuan)(yuan)：即(ji)單(dan)相220伏(fu)電(dian)(dian)(dian)源(yuan)(yuan)，單(dan)相380伏(fu)電(dian)(dian)(dian)源(yuan)(yuan)，三(san)相380伏(fu)電(dian)(dian)(dian)源(yuan)(yuan)，第(di) I 種家用比較多，第(di)三(san)種工廠(chang)里電(dian)(dian)(dian)機類用得多，第(di)二種用得少(shao)，只有交流電(dian)(dian)(dian)焊機經(jing)常(chang)用到單(dan)相380伏(fu)電(dian)(dian)(dian)源(yuan)(yuan)。