单项选择题

一台三相感应电动机,定子△连接,U N =380V,f=50Hz,P N =7.5kW,n N =960r/rain,额定负载时cosφ 1 =0.824,定子铜耗474W,铁耗231W,机械损耗45W,附加损耗37.5W,则额定负载时转子铜耗P Cu2 为______


A.315.9W B.329.1W
C.312.5W D 303.3W