摘要
在确定电力电缆额定载流量时,必须精确计算金属护套、铠装等结构的损耗因数,尤其对于金属护套采取两端直接互联接地的高压单芯电缆线路,如大长度海底电缆。简单对称敷设情况下护套和磁性铠装结构的损耗因数可以根据IEC 60287中推荐的公式进行计算;若铠装采用非磁性材料,可按照标准中推荐的处理方法获得总的损耗因数,再按两者并联的方式进行分配,获得各自的损耗因数。其它非磁性金属结构按照类似方法处理。当然,也可从基本的等效电路出发,求解电缆金属护套、加强层、铠装层等结构中流过的环流,从而获得损耗因数,这种方法可应用于更复杂或一般性的电缆结构和敷设情况。两种计算方法各有优缺点,可根据需要选用。
When determining the nominal current rating of power cables, loss factors of metal layers such as the sheath and armour must be calculated accurately, especially for high-voltage single-core cables whose metal layers are collected and grounded directly at both sides of the cable line. Some calculation methods for loss factors of cables in simple symmetric configurations such as those in flat or trefoil arrangements are recommended by IEC 60287. For more complex cable structures and complicated practical arrangements, an equivalent circuit should be established and an equation set be created whose solutions are circulating currents in the metal layers such as sheath, strengthen and armour, and accordingly loss factors can be obtained. Selection between these two methods is condition-based.
出处
《电线电缆》
2013年第2期1-3,20,共4页
Wire & Cable
关键词
电力电缆
金属护套
铠装
环流
损耗因数
power cables
metal sheath
armour
circulating current
loss factors
