Power is defined as the
time rate of doing work. In an AC circuit, power quantities are continuously varying.
Capacitive, resistive, and inductive loads help us identify the amount of power
in the circuit and in its elements. Power can be absorbed or supplied by circuit
elements. There are formulas for finding the Instantaneous, Average, and
Maximum power in an AC circuit.
For Instantaneous Power:
P(t)= ½ Vm Im cos(Ѳv – Ѳi) + ½ Vm Im cos(2ῳt
+ Ѳv + Ѳi)
-To solve the instantaneous power, you just simply
substitute the solved/given voltage, current and their phase angles and also
the angular frequency. P is also not time dependent.
For Average Power:
P(t)= ½ Vm Im cos(Ѳv – Ѳi)
-This formula is just similar to instantaneous power, but
the ½ Vm Im cos(2ῳt + Ѳv + Ѳi) was removed.
For
Maximum Power:
P(t)= ½ (I^2) Rl
But if you substitute other formulas, expand, and use
derivation, the final formula would be:
1/8 (Vth^2 / Rth)
-Vth and Rth are only the real part of the obtained
voltage and Impedance.
