AC Nodal Analysis Adding source phase angles AFTER calculation?

In summary, the conversation revolves around finding Vth, Rth and Vo for a circuit with a source phase angle of 30 degrees. The method of solving involves ignoring the phase angle and adding it back at the end. The person initially doubts the validity of this method but later realizes their mistake and confirms that it does work.
  • #1
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Just to clarify the title... Basically for the below circuit we are required to find Vth, Rth and Vo. However, the method of solving this problem is a little strange to me, because as you can see, the source has a phase angle of 30 degrees. The solution to this problem basically says (to find Vth), ignore the 30 degree phase angle, and jam it back onto the final solution at the very end. Ie, solve the circuit with the phase angle from the source equal to 0, and add it back at the very end.

http://img577.imageshack.us/img577/6463/ecquestion.png Something doesn't seem quite right, because I can't actually get my answer computed with everything in place to equal the answer with the angle added in later.

So what I really want to ask is, is this a valid method of solving the equation or not? Any help would be appreciated.
 
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  • #2
Nevermind... I confirmed this actually does work. For some reason I was setting Io equal to (V1-20)/4 instead of (20-V1)/4. I seemed to have not taken into account the current direction.
 

FAQ: AC Nodal Analysis Adding source phase angles AFTER calculation?

What is AC nodal analysis?

AC nodal analysis is a method used to analyze circuits in alternating current (AC) circuits. It involves using Kirchhoff's current law (KCL) and Kirchhoff's voltage law (KVL) to determine the unknown voltages and currents in a circuit.

How is AC nodal analysis different from DC nodal analysis?

The main difference between AC and DC nodal analysis is that AC nodal analysis takes into account the frequency of the alternating current, while DC nodal analysis only considers direct current. This means that in AC nodal analysis, phasors and complex numbers are used to represent the voltage and current values, while in DC nodal analysis, simple scalar values are used.

What is the purpose of adding source phase angles after calculation in AC nodal analysis?

Adding source phase angles after calculation in AC nodal analysis is necessary because AC circuits involve sinusoidal waveforms that have a specific phase angle. By adding the source phase angles, the overall phase shift in the circuit can be determined and used to calculate the correct voltage and current values.

How are source phase angles determined in AC nodal analysis?

Source phase angles can be determined by using the circuit's impedance values and the voltage and current values at the source. By calculating the impedance and using the complex representation of the voltage and current, the phase angle can be found using trigonometric functions.

Are there any limitations to using AC nodal analysis with source phase angles?

Yes, there are limitations to using AC nodal analysis with source phase angles. This method is only applicable to linear circuits, meaning that the components in the circuit must have a linear relationship between voltage and current. Additionally, the circuit must be in steady-state, meaning that all voltages and currents have reached their steady-state values and are not changing over time.

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