單相電功率功課

交流電源
電壓 = 220V
頻率 = 50Hz
電阻器的電流 IR = 12A
電感器的電流 IL = 18A
電容器的電流 IC = 3A
IX = (IL - IC) = 18A - 3A = 15A

圖片參考：http://imgcld.yimg.com/8/n/HA00639401/o/700912170161813873385500.jpg


求電路
1.總電流 = √ IX + IR
= √ (15x15) + (12x12)
= √ 225 + 144
= √ 369
= 19.2A

2.功率因數 = tanφ = toa = o/a
= 12/15 = 0.8tanφ = 0.78cosφ

3.視在功率 = VA = V x I
= 220 x 19.2
= 4224VA

4.有功功率 = W = V x I x PF
= 220 x 19.2 x 0.78
= 3294.72W

5.無功功率 = W x tanφ
= 3294.72 x 0.8
= 2635.78VAR

2.單相電動機之輸入功率2kW,功率因數是0.8,接於電壓220V,頻率50HZ的電源上,

1.求電動機???
唔明你問咩

2.輸入電流 = I = P/(VxPF)
= 2000 / (220 x 0.8 )
= 2000 / 176
= 11.36A

3.視在功率 = VA = V x I
= 220 x 11.36
= 2499.2VA

4.無功功率 = VAR = W x tanφ
= 2000 x 0.75
= 1500VAR


### 0.8cosφ = 0.78tanφ φφφ


如有錯漏, 祈請更正, 差錯相坐