9th Week: "AC Power Analysis"

"AC Power Analysis"

Our study in ac circuit analysis so far has been focused mainly on calculating voltage and current. Our major concern in here is power analysis.

Instantaneous and Average Power

The instantaneous power p(t) absorbed by an
element is the product of the instantaneous voltage v(t) across the element and the instantaneous current i(t) through it. Assuming the passive sign convention,

p(t) = v(t) i(t)

Where,

v(t) = Vm cos(ωt + θv)
i(t) = Im cos(ωt + θi)

Average Power

The average power is the average of the instantaneous power over one period.

Maximum Average Power Transfer 

We solved the problem of maximizing the power delivered by a power-supplying resistive network to a load RL. Representing the circuit by its Thevenin equivalent, we proved that the maximum load if the load resistance is equal to the Thevenin resistance RL = RTh. We now extend that result to ac circuits.


In rectangular form, the Thevenin impedance ZTh and the load impedance ZL are,

ZTh = RTh + jXTh

ZL = RL + jXL

For maximum average power transfer, the load impedance ZL must be equal to the complex conjugate ofthe Thevenin impedance ZTh.

Effective or RMS Value

The effective value of a periodic current is the dc current that delivers the same average power to a resistor as the periodic current.

The effective value of a periodic signal is its root mean square (rms) value.

Learning:

• Power analysis is another chapter and view of understanding in our class since it has lesser circuit analysis. Power is the most important quantity in electric utilities, electronic, and communication systems, because such systems involve transmission of power from one point to another.

Videos:

For more information, watch the video below:

That's all. Thank You for visiting my blog.

GOD Bless! :)

By:

AYALA, ARNY  S.   BSECE -3

ECE 321

Professor:

ENGR. JAY S. VILLAN, MEP - EE