、复阻抗为 Z 的三相对称电路中，若保持电源电压不变，当负载接成星形时消耗的有功功率为 P Y ，接成三角形时消耗的有功功率为 P D ，则两种接法时有功功率的关系为 ( ) 。

A、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/ueditor/jsp/upload/image/20161104/1478223751703014037_blob.png" title="7116075608499193" alt="blob.png"/>

B、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/ueditor/jsp/upload/image/20161104/1478223760337044533_blob.png" title="4171063672766968" alt="blob.png"/>

C、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/ueditor/jsp/upload/image/20161104/1478223767708007630_blob.png" title="6039599796254233" alt="blob.png"/>