Drive a formula of instantaneous power for single-phase AC power system in the following different loads. i. Pure resistive load ii. Pure inductive load iii. Pure capacitive load iv. RLC load
The instantaneous power is the power at the moment. Assume that we have a current and voltage of
The power for the pure resistive load will be
Pure inductive load: since current lags voltage for , the instantaneous active power is 0.
Pure capacitive load: since voltage lags current for 90°, the instantaneous power is 0.
For an RLC circuit, the impedance is
The phase shift then is
Substitute this value in the common equation for power above to find the numerical value of instantaneous power.