三相电路的有功功率、无功功率、视在功率、三相负载的功率因数计算公式

一般的三相电路，无论它对称与否，其瞬时功率、平均功率和无功功率分别为各相的对应功率之和。

1．有功功率

在三相电路中，三相负载吸收的有功功率等于各相有功功率之和，即文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

在对称三相电路中，各相负载吸收的有功功率相等，即，所以三相有功功率文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

对称三相电路无论负载是星形连接还是三角形连接总有文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

所以对称三相电路的有功功率也可以表示为文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

２．无功功率

与三相有功功率相类似，三相负载的无功功率为文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

在对称三相电路中，三相无功功率文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

文章源自公式库网-https://www.gongshiku.com/html/201808/sanxiangdianludeyougonggongshuaiwugonggongshuaishizaigongshuaisanxiangfuzaidegongshuaiyinshujisuangongshi.html

3．视在功率

三相视在功率为：

在对称情况下：

4．三相负载的功率因数