怎樣計算高壓電纜載流量

     在(zai)理論(lun)上(shang)講，高壓(ya)電(dian)(dian)(dian)(dian)(dian)纜載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)計(ji)算(suan)(suan)(suan)(suan)(suan)公(gong)式(shi)：最(zui)(zui)(zui)大(da)載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)＝電(dian)(dian)(dian)(dian)(dian)纜斷面(mian)積（mm2）×這種電(dian)(dian)(dian)(dian)(dian)纜材質的(de)(de)(de)(de)(de)(de)允(yun)許最(zui)(zui)(zui)大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)度（A/mm2）導線(xian)(xian)截(jie)面(mian)積與載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)的(de)(de)(de)(de)(de)(de)計(ji)算(suan)(suan)(suan)(suan)(suan)：一般(ban)銅(tong)(tong)導線(xian)(xian)載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)導線(xian)(xian)的(de)(de)(de)(de)(de)(de)安(an)(an)全載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)是(shi)根據所允(yun)許的(de)(de)(de)(de)(de)(de)線(xian)(xian)芯最(zui)(zui)(zui)高溫度、冷卻條(tiao)件(jian)、敷設條(tiao)件(jian)來確定(ding)的(de)(de)(de)(de)(de)(de)；一般(ban)銅(tong)(tong)導線(xian)(xian)的(de)(de)(de)(de)(de)(de)安(an)(an)全載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)為(wei)5~8A/mm2，鋁導線(xian)(xian)的(de)(de)(de)(de)(de)(de)安(an)(an)全載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)為(wei)3~5A/mm2。如(ru)(ru)：2.5 mm2 BVV銅(tong)(tong)導線(xian)(xian)安(an)(an)全載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)的(de)(de)(de)(de)(de)(de)推(tui)薦(jian)值(zhi)2.5×8A/mm2=20A 4 mm2 BVV銅(tong)(tong)導線(xian)(xian)安(an)(an)全載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)的(de)(de)(de)(de)(de)(de)推(tui)薦(jian)值(zhi)4×8A/mm2=32A計(ji)算(suan)(suan)(suan)(suan)(suan)銅(tong)(tong)導線(xian)(xian)截(jie)面(mian)積利(li)用(yong)(yong)銅(tong)(tong)導線(xian)(xian)的(de)(de)(de)(de)(de)(de)安(an)(an)全載(zai)(zai)(zai)流(liu)(liu)(liu)量(liang)(liang)的(de)(de)(de)(de)(de)(de)推(tui)薦(jian)值(zhi)5~8A/mm2，計(ji)算(suan)(suan)(suan)(suan)(suan)出所選取銅(tong)(tong)導線(xian)(xian)截(jie)面(mian)積S的(de)(de)(de)(de)(de)(de)上(shang)下范圍： S=< I /（5~8）>=0.125 I ~0.2 I（mm2） S-----銅(tong)(tong)導線(xian)(xian)截(jie)面(mian)積（mm2） I-----負(fu)載(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)（A）功(gong)率(lv)計(ji)算(suan)(suan)(suan)(suan)(suan)一般(ban)負(fu)載(zai)(zai)(zai)（也可以(yi)(yi)成為(wei)用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)器，如(ru)(ru)點燈(deng)、冰箱等等）分為(wei)兩種，一種式(shi)電(dian)(dian)(dian)(dian)(dian)阻性負(fu)載(zai)(zai)(zai)，一種是(shi)電(dian)(dian)(dian)(dian)(dian)感性負(fu)載(zai)(zai)(zai)。對(dui)于(yu)電(dian)(dian)(dian)(dian)(dian)阻性負(fu)載(zai)(zai)(zai)的(de)(de)(de)(de)(de)(de)計(ji)算(suan)(suan)(suan)(suan)(suan)公(gong)式(shi)：P=UI 對(dui)于(yu)日(ri)光(guang)燈(deng)負(fu)載(zai)(zai)(zai)的(de)(de)(de)(de)(de)(de)計(ji)算(suan)(suan)(suan)(suan)(suan)公(gong)式(shi)：P=UIcosф，其(qi)中日(ri)光(guang)燈(deng)負(fu)載(zai)(zai)(zai)的(de)(de)(de)(de)(de)(de)功(gong)率(lv)因(yin)數cosф=0.5。 不同(tong)電(dian)(dian)(dian)(dian)(dian)感性負(fu)載(zai)(zai)(zai)功(gong)率(lv)因(yin)數不同(tong)，統一計(ji)算(suan)(suan)(suan)(suan)(suan)家庭(ting)用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)器時可以(yi)(yi)將功(gong)率(lv)因(yin)數cosф取0.8。也就是(shi)說如(ru)(ru)果(guo)一個家庭(ting)所有用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)器加(jia)上(shang)總(zong)功(gong)率(lv)為(wei)6000瓦(wa)，則最(zui)(zui)(zui)大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)是(shi) I=P/Ucosф=6000/220*0.8=34(A) 但(dan)是(shi)，一般(ban)情況下，家里的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)器不可能(neng)同(tong)時使用(yong)(yong)，所以(yi)(yi)加(jia)上(shang)一個公(gong)用(yong)(yong)系數，公(gong)用(yong)(yong)系數一般(ban)0.5。所以(yi)(yi)，上(shang)面(mian)的(de)(de)(de)(de)(de)(de)計(ji)算(suan)(suan)(suan)(suan)(suan)應該(gai)改(gai)寫成 I=P*公(gong)用(yong)(yong)系數/Ucosф=6000*0.5/220*0.8=17(A) 也就是(shi)說，這個家庭(ting)總(zong)的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)值(zhi)為(wei)17A。則總(zong)閘空氣開關不能(neng)使用(yong)(yong)16A，應該(gai)用(yong)(yong)大(da)于(yu)17A的(de)(de)(de)(de)(de)(de)。