> 基本上除非電路內有特殊的裝置,否則I&V的ω會相同
> But p=IVcosθ is correct only for "resistance",not"impedance"
> impedance Z is R+iX ,R is resistance,and X is inductive reactanc(感抗),
> and 容抗.
> 假設一電線內,三項電壓是 V(t)=Vmax*cos(ωt+θ) ,V(t)=Vmax*cos(ωt+θ+120度)
> and V(t)=Vmax*cos(ωt+θ-120度)
> θ只是在t=0時,wave在Y軸的交點位置(如θ=0 cos0=1,V在最大值Vmax)
> it doesn't mean anything.
> 而傳輸出去後,迴路中會有電感電容和電阻效應,
> so it will change the phase of the "Current"
> In the calculation,∠θ=實部+i虛部,and 電感=i虛部,電感=-i實部,
> so we can know the effect of the impedance.
> 對於交流電,P(total)=IV永遠成立
> 而p=IVcosθ的p和上一行P定義不同(以大小寫區分)(可參考任何一本基礎電路學課本)
^^^^^^^^^^^
忘了說..
此θ不同於上面的V=Vmax*cos(ωt+θ)的θ
此θ指電流和電壓的相對角度,此角度由impedance Z 決定.
> 此p 指 the power to the resistant element.
> the power to the positive or negative element(電感和電容) is "Q"
> so P(total)=I(total)*V(total)=p +iQ
> This equation is correct for any situation.
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