회로이론
회로이론
역률
2003.8 기출
\(V=80+j60\)[V], \(I=4+j2\)[A]인 부하의 역률·무효율은?
- ① 0.8, 0.6
- ② 0.894, 0.448
- ③ 0.916, 0.401
- ④ 0.984, 0.178 정답
📖 해설
복소전력 \(S=VI^*\)
\(I^*=4-j2\), \(S=(80+j60)(4-j2)=320-j160+j240+120=440+j80\).
\(\cos\theta=\dfrac{440}{\sqrt{440^2+80^2}}=\dfrac{440}{447}\approx0.984\), 무효율 \(\approx0.178\).
\(I^*=4-j2\), \(S=(80+j60)(4-j2)=320-j160+j240+120=440+j80\).
\(\cos\theta=\dfrac{440}{\sqrt{440^2+80^2}}=\dfrac{440}{447}\approx0.984\), 무효율 \(\approx0.178\).