Questions tagged [phasor]

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Phasor angle calculation

In this example, for Vo it first says it is lagging by -134.8 degrees, however when then calculating actual Iin, the angle for Vo becomes -138.4. I'm wondering if -134.8 is a typo, and if it isn't; ...
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1answer
57 views

Does Clarke transformation convert scalar quantity to vector quantity?

Current is a scalar quantity, is it converted to vector quantity using Clarke's transformation? If it is correct, I would like to know how transformation converts from scalar to vector? Thanks and ...
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35 views

Phasorial notation

In the phasorial notation (of a voltage or current, for example), should i use the peak value of a sinusoidal wave or its effective value (rms)? I ask this, because i get confused after reading some ...
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2answers
47 views

KVL in the frequency domain - Why is the sum of phasors 0 and not just the real part of the sum?

In many proofs of Kirchhoff's voltage law for the frequency domain, the time-domain KVL is originally used and then the time-dependent part (\$e^{jwt}\$) is removed, leaving only the real part of the ...
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38 views

About simulating an ac circuit in Pspice

Firstly, It's not homework. I already know the answer. But I couldn't see sinusoidal waves to calculate phase of voltage(V0) across the capacitor. Response of capacitor is look like damping. However, ...
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1answer
49 views

Phase angle of sine wave (confusion)

Usually, phasors are represented by Acos(ωt + φ) where φ is the phase angle. Using this convention, we need to convert sin(ωt) into cos(ωt - 90) to get its phase angle like this thumbnail on a YouTube ...
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1answer
69 views

Differential Equations vs Phasor vs Laplace

I've just read a book on basic circuit theory and I'd like to understand the pros and cons of each analysis method. Time Domain Usually ends up in differential equations for reactive circuits. Gives ...
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1answer
71 views

Band stop filter RLC circuit frequency response

Assume we have an $ RLC $ circuit as described in the picture This should be a Band-stop filter. But somethings bother me in my calculations. This is my calculations for the frequency response: Using ...
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1answer
62 views

Explaination on phasor diagram for RL circuit?

This is the phasor diagram which I had drawn from the value of phase difference(deg) from MULTISIM. I'm a bit confuse here... shouldn't by theory, when inductance is increase, thus the degree for Vl ...
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1answer
78 views

Why voltage in capacitor lags behind the source voltage in RC circuit?

Voltage across the capacitor lags behind the current through capacitor as we know. But why the voltage across the capacitor lags behind the source voltage in this circuit ? Similarly it is found that ...
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1answer
679 views

Converting from time domain to phasor domain?

If I have a voltage source of a circuit \$V_s(t) = 8\cos(24\pi*10^9t-60^{\circ})\$ (V) and I want to convert it to the phasor domain would it be this? \$8e^{-j60^{\circ}}\$?
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3answers
101 views

IQ modulation and phasors: which first?

Do we use IQ modulation because quadrature signals are a good physical implementation of phasors - or is it the other way around? To elaborate a little:I'm having a hard time getting a clear ...
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2answers
43 views

Why is the phase angle in the summation of the phasors the negative arctan?

I was reading a textbook and came across the following $$ \\I_1 = Ae^{j0} = A \\I_2 = Be^{-j\frac{\pi}{2}} \\\bf{I} = I_1 + I_2 \\If\ A=10\ and\ B=20 \\|I| = \sqrt{A^2 + B^2} \\\angle I = -tan^{-1}(B/...
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1answer
36 views

Can AC harmonic quantities be expressed as a sum of phasors of different frequencies without confusion?

https://www.electronics-tutorials.ws/accircuits/harmonics.html The problem with AC harmonics is that each term has a different frequency, being a integer factor of the first frequency. I was wondering ...
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1answer
58 views

What am I doing wrong in finding the phase angle of power?

Consider a voltage supply \$V\angle \phi_1\$ and a circut with impedance \$Z \angle \phi_2\$. Now the Apparent power(\$S\$) is given by: $$\bar S =\frac{(\bar V)^2} {\bar Z}$$ Thus phase angle of \$S\$...
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47 views

is it possible for the phase difference between voltage and current to exceed pi/2 in a RL circuit?

I did an experiment where I made a RL circuit. My IV was resistance and DV was phase difference between voltage and current. To find the phase difference, I took the difference (Δt) between time when ...
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1answer
56 views

Phase-shift a Broadband Time-Domain Function

Suppose we have an operator \$A_\phi\$ which phase-shifts a sinusoid by \$\phi\$: $$A_\phi[\cos(\omega t)] = \cos(\omega t + \phi)$$ In phasor domain, \$A_\phi = e^{+j\phi}\$ is a complex constant. I ...
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3answers
165 views

Why can't circuit breakers close across a large phase angle difference?

In power systems I understand that breakers have mechanisms preventing their closing if they detect the phase angle (and voltage) across them to be too large. This is usually called a 'sync check'. ...
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1answer
67 views

RMS values and Phasors

I need to solve these two exercises but I really have no idea where to start. How should I proceed to solve this kind of problems? I tried to find something on my teacher's files but haven't ...
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1answer
28 views

How do I transform this sinusoid in phasor?

If it is a signal like this i(t)=5*sin(100t-pi/3)A, I know how to transform. But how do I do this e(t)=2-√(2)*sin(10t+pi/4) ? I meant I don't know what to do with "2-" Thanks for the help!
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1answer
214 views

How to calculate rotor flux of the three phase squirrel cage induction motor?

I have a three phase squirrel cage induction motor with given parameters (stator winding connected in delta) nominal power: \$P_n = 22.4\,\mathrm{kW}\$ nominal stator voltage: \$V_{sn} = 230\,\mathrm{...
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1answer
69 views

RC circuit - phase current

I have a simple RC circuit as below : I'm trying to visualize current curve and voltage curve (Vout and I(R1)) vs Vin using LtSpice and I obtain the result below: It's OK that the Vout is leading ...
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4answers
75 views

can I also use phasors/concept of impedances for non sinusodial signals?

I know that phasors are great to solve circuits driven by sinusodial input signals but I was wondering if I can incorporate phasor concepts(like impedance) to circuits driven by input signals not ...
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1answer
74 views

Complex impedances of capacitors/inductors in the phasor domain

I'm trying to verify the complex impedances of passive components in the phasor domain (not s-domain). Take for example the inductor, whose element law is \$ v = L \frac{di}{dt} \$. Assuming a complex ...
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2answers
53 views

Resonant frequency and maximum signal width

I've seen resonant frequency being defined as the point where the input signal is in phase with the output signal (So reactance/susceptance is 0). However conceptually, teaching material seems to link ...
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1answer
81 views

Finding the total impedance and voltage across open terminals

The question that I'm trying to solve is the following: In the circuit shown below, what is the total impedance in ohms across the open terminals? What is \$v_{T}\$ if \$v_{L}\$ is 80 vrms? This is ...
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2answers
408 views

Calculating Phase angle from instantaneous voltage

For background info I am an EE/CE that is 10 years out of school and has since worked writing firmware and dealt mostly with digital communications and signals, so now I am having to reach back to my (...
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3answers
78 views

How can current be in different phases in the same wire at the same time?

We know that either in ideal or practical transformer in no-load condition, the exciting current has two components Ic(core loss component) and Im(magnetizing component). Now since the same current ...
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0answers
38 views

Rotating magnetic field discrepancy

This may be a noob question Lets consider a balanced 3 phase supply namely \begin{align} R&= V \sin(x)\\ Y&= V \sin(x-120)\\ B&= V \sin(x+120) \end{align} At a neutral point we would ...
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1answer
217 views

How to calculate voltage across capacitor C1?

If the voltage \$v_I = \frac{jωC1R3}{1 + jωC1R3}*Vs \$ does that mean the voltage across the capacitor would be equal to \$v_S - v_I\$ ?
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1answer
324 views

Integral of phasor

Say \$v(t) = V_m\cos(\omega t+\phi)=\Re[V_me^{j(\omega t +\phi)}] = \Re[Ve^{j\omega t}]\$, where \$V_me^{j\phi} = V\$. Integrating gives \$\int\limits_0^t v(t)\,dt = \Re\int\limits_0^t Ve^{j\omega ...
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1answer
782 views

Polar form vs phasor form?

I know that polar form has two parts. Amplitude and angle but What is difference between polar form and phasor form of complex numbers? Or phasor form just includes amplitude form of a complex number?...
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1answer
59 views

Current divider usage

I was solving this exercise where I have to find the current through each of the circuit branches. Sorry if the image is a bit confusing but after determining the current I I used the current divider ...
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2answers
60 views

Finding 70% Voltage Point

Let \$v_1\$ be the input AC voltage and \$v_2\$ be the output AC voltage such that gain \$\dfrac{v_2}{v_1} = \dfrac{A+jB}{D+jE}\$ where \$j = \sqrt{-1}\$. How should I find the 70% point (the point ...
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1answer
177 views

Help on (another) triphasic exercise

Second this week... But was it easy I wouldn't be here... A problem asked me to identify the diagrams from this picture: The following are the correct answers, acording to the test developers. a. ...
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0answers
186 views

Relation between phase angle and current direction

In a triphasic system (any), is there a way to tell if the current is entering or leaving a phase/line/load just by the angle of the phasor of the source ? In the following picture we can see the ...
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2answers
133 views

Derivation of telegrapher's equations

I'm currently going over the derivation of the telegrapher's equations shown here, but there's a step that I'm not fully grasping. I think I can follow some of how you get from eq.3 to eq.5: If the ...
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5answers
2k views

Does an oscilloscope subtract voltages as phasors?

I want to measure two voltages on an oscilloscope. They are not in phase. I want to know the magnitude of the voltage difference. The oscilloscope has an in-build math function to subtract the ...
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0answers
167 views

Superposition theorem with phasors [duplicate]

Can someone explain the superposition theorem step by step when applied with phasors (AC circuits)? I think books and websites mostly include examples of how to solve something with superposition but ...
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1answer
51 views

Complex Amplitudes and Exp'l Increase/Decrease

The following are quotes from a textbook, If S(t) is represented as a rotating phasor, the angular frequency of the phasor can be thought of as velocity at the end of the phasor. In particular ...
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4answers
161 views

Is the frequency response of a circuit only valid for steady state (phasors)?

This is my first post. I just finished a course about advanced circuit analysis techniques (the content was taken from textbooks by Sadiku, Hayt and Irwin.) As you know, phasors are used to solve ...
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1answer
323 views

Transformer's Primary and Secondary Voltages

In general, which is the phase relationship between the primary and secondary voltages of an ideal transformer? Does it depends on the dot convention?
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1answer
1k views

Phasors and Fourier Transform

I have always been told that for a sinusoidal variable (for instance a voltage signal), the fourier transform coincides with the phasor definition, and this is the reason why the analysis of ...
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1answer
44 views

AC signal analysis: Voltage dip (amplitude dip) at time = 0

I'm working on a series RLC problem where the input voltage is a sinusoidal function for all time. The catch is, for t < 0, the sinusoidal function is of greater magnitude than t >= 0. There is no ...
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33 views

What is the DC component of the sum of phasors?

I am preparing for the written test conducted by IISc Bangalore for admission into their graduate program. I happened to come across a sample paper from 2016, I think. I am struggling to understand ...
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3answers
554 views

How does one relate an RC circuit's time domain solution to phasors?

It seems to be a given for phasor analysis that the voltage across a capacitor can be defined as follows: $$ V_{C}(t) = V_{A}\cos(\omega t + \phi)\tag{1} $$ Where Vc(t) is the capacitor's voltage at ...
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5answers
480 views

Why can phasors be used simplify getting instantaneous power from instantaneous curent and voltage?

If instantanoeus power is p(t) and instantaneous voltage and current saying for a resistor are v(t) and i(t), then p(t)=i(t)*v(t). But if you convert v(t) and i(t) to their respective phasors and ...
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1answer
76 views

Is my calculated capacitor sign correct?

I have the following circuit where I would like to obtain an analytic expressions for the value of \$Cs\$ and \$Rs\$ only kowning the phasors \$\bar Vina\$ and \$\bar Vinb\$ there displayed, I don't ...
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2answers
199 views

Phasors: why is my book using sines?

When I learned phasors I learned we passed from sinusoidal to phasor this way: $$\sqrt{2} V\cos(\omega t+\phi) \rightarrow \sqrt{2} Ve^{j\phi}$$ However I'm now studying for a book that does this: $...
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2answers
103 views

Output of AC op amp circuit has unknown superimposed signal on top of expected output signal

I am trying to find the voltage gain of a certain ideal op amp circuit with a sinusoidal input. However, when I simulate the circuit, the output shown seems to be my calculated output but with a ...