三相電加熱管

        380伏(fu)三相(xiang)四線(xian)電(dian)(dian)(dian)(dian)路中(zhong)，任意(yi)兩(liang)根火線(xian)之間的電(dian)(dian)(dian)(dian)壓都是380伏(fu)，任意(yi)一根火線(xian)與零(ling)線(xian)之間都可以組(zu)成220伏(fu)。這(zhe)個(ge)系統可以形(xing)成三種(zhong)(zhong)電(dian)(dian)(dian)(dian)源(yuan)(yuan)：即單(dan)相(xiang)220伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，單(dan)相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，三相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，第 I 種(zhong)(zhong)家用(yong)比較多(duo)，第三種(zhong)(zhong)工廠里電(dian)(dian)(dian)(dian)機類用(yong)得多(duo)，第二(er)種(zhong)(zhong)用(yong)得少，只有交(jiao)流電(dian)(dian)(dian)(dian)焊機經常用(yong)到單(dan)相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)。