三相電加熱管

        380伏(fu)(fu)三相四線(xian)電(dian)(dian)路中，任(ren)意(yi)兩(liang)根(gen)火(huo)線(xian)之間的電(dian)(dian)壓都是380伏(fu)(fu)，任(ren)意(yi)一根(gen)火(huo)線(xian)與零線(xian)之間都可(ke)以組成220伏(fu)(fu)。這個系統可(ke)以形成三種(zhong)(zhong)電(dian)(dian)源(yuan)(yuan)：即(ji)單相220伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，單相380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，三相380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)(zhong)家用比較多，第(di)三種(zhong)(zhong)工廠里電(dian)(dian)機類用得多，第(di)二(er)種(zhong)(zhong)用得少，只有交流電(dian)(dian)焊機經常用到單相380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)。