AC Power Calculations: Understanding Real & Reactive Powers

[Dissonance in E]

Hi, I am a bit lost with AC circuits on the whole and could use some dumbed down explanation on the matter.

Taking an example from course material:

(Components connected in parallel. "Ladder connection")

------
l l l l l
J C L R
l l l l l
------

Where
J = 1 (30 degrees) currentsource driving current in the clockwise direction
C = 0.05 F capacitor
L = 0,2 H inductor
w = 10 rad/s

If I am asked to find the real and reactive powers for each component how would i go about solving these?
I could also use a clarification on the difference between real and reactive powers.

Thanks.

ps: sory for the dingy "diagram"
Edit/Delete Message

 

[tiny-tim]

If I am asked to find the real and reactive powers for each component how would i go about solving these?
I could also use a clarification on the difference between real and reactive powers.

Hi Dissonance in E!

Reactive power is just the imaginary part of the complex power, which is the (instantaneous) voltage times current.

(and reactive or imaginary power involves no net transfer of energy)

 

[Mene]

Sure, I'd be happy to explain AC power calculations and the difference between real and reactive powers.

First, let's start with the basics. In an AC circuit, the current and voltage are constantly changing, unlike in a DC circuit where they remain constant. This is because AC stands for "alternating current," meaning the direction of the current switches back and forth.

Now, let's talk about power. Power is the rate at which energy is transferred or used. In an AC circuit, there are two types of power - real power and reactive power.

Real power, also known as active power, is the power that is actually being used by the circuit to do work. It is measured in watts (W) and is represented by the symbol P. In your example, the real power would be the power being used by the components (J, C, L, and R) to do work.

Reactive power, on the other hand, is the power that is not being used to do work, but rather is being stored and released by the components. It is measured in volt-amperes reactive (VAR) and is represented by the symbol Q. In your example, the reactive power would be the power being stored and released by the capacitor (C) and inductor (L).

Now, to find the real and reactive powers for each component in your example, you would need to use the following formulas:

Real Power (P) = Voltage (V) x Current (I) x Cosine of the phase angle (cosθ)

Reactive Power (Q) = Voltage (V) x Current (I) x Sine of the phase angle (sinθ)

In your example, the phase angle (θ) for the current source (J) is given as 30 degrees, so you would use this angle in the formulas.

I hope this helps to clarify the concept of real and reactive powers in AC circuits. Let me know if you have any other questions or need further explanation. Good luck with your studies!