Power in RLC Circuits Flashcards
What is the equation for resistive power of an AC circuit?
P = iv P = Vsin(ωt)Isin(ωt) P = (V^2/R)((1-cos(2ωt))/2)
How does voltage and current vary in an AC circuit with just resistive components?
They vary sinusoidally in phase
What is the equation for reactive power of an AC circuit for a capacitor?
P = iv P = Vsin(ωt)Icos(ωt) P = (IV/2)sin(2ωt) P = (V^2/2Xc)sin(2ωt)
Prove I = V/Xc
I = V/Z Z = 1/jωC I = V/(1/jωC) I = V/(-j/ωC) I = V/-jXc I = V/Xc
What is the equation for the peak reactive power of a capacitor?
Q = V^2/2Xc
For an AC circuit with a capacitor, who leads who?
Current leads voltage
What is the equation for reactive power of an inductor?
P = iv P = Vsin(ωt)(-Icos(ωt)) P = (IV/2)(-sin(2ωt)) P = -(V^2/2Xl)sin(2ωt)
Prove I = V/Xl
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What is the equation for the peak reactive power of an inductor?
Q = V^2/2Xl
For an AC circuit with a capacitor, who leads who?
Current leads Voltage
What is the equation for calculating power in an RC circuit?
P = iv P = Vsin(ωt)Isin(ωt + ϕ) P = (IV/2)[cos(ϕ) - cos(2ωt + ϕ)]
How is the phase angle calculated for an RC circuit?
ϕ = tan^-1(Xc/R)
What is the equation for calculating power in an RL circuit?
P = iv P = Vsin(ωt)Isin(ωt + ϕ) P = (IV/2)[cos(ϕ) - cos(2ωt + ϕ)]
How is the phase angle calculated for an RL circuit?
ϕ = - tan^-1(Xl/R)
[REMEMBER THE NEGATIVE SIGN]
What is active power? What are its other names, its symbol, and units?
This is the power that the circuit dissipates.
Symbol: P
Unit: Watts, W
What are the 2 equation to calculate active power?
P = IV P = Apparent power × Power factor
What is reactive power? What is its symbol and units?
This is the power that is not dissipated by the circuit but is transferred between components.
Symbol: Q
Unit: var (VAreactive)
What is apparent power?
This is the combination of active and reactive power.
It is complex because of both the active and reactive component.
What is the symbol and unit for apparent power?
Symbol: S
Unit: VA (VoltAmpere)
What are the equations to calculate apparent power?
S = P + jQ S = V × I*
What is the equation for power factor?
Power factor = Real power/Apparent power