发布时间:2025-02-09 05:08:23
首先,mm2是指电缆截面即圆的面积(平方毫米),由面积公式:
S=π * r2=3.14*1/2R2=???mm2
比如:你说得如果不是四等芯的、不带钢带的即:由4.5CM=45mm便是3*150+1*70=520mm2的电缆。按照公式计算:r=√S/π=√520mm2/3.14==45mm==4.5CM
刚装修的房子 开门后墙体烈缝 不开门异味重 咋办 具体什时候房子才能完全凝固好
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