三相四线电能表有功功率表达式是( )。
AP=UaIacosφa+UbIbcosφb+UcIccosφc
BP=UaIasinφa+UbIbsinφb+UcIccosφc
CP=UaIatgφa+UbIbtgφb+UcIctgφc
DP=UaIactgφa+UbIbctgφb+UcIcctgφc
AP=UaIacosφa+UbIbcosφb+UcIccosφc
BP=UaIasinφa+UbIbsinφb+UcIccosφc
CP=UaIatgφa+UbIbtgφb+UcIctgφc
DP=UaIactgφa+UbIbctgφb+UcIcctgφc