# Questions tagged [phasor]

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### Why is one current reading ~20% higher than the other two in a balanced high-leg delta load?

We are using eGuage watthourmeters to monitor the outdoor unit on five VRF systems powered by two different 3P4W 120/208V high-leg delta panels. The neutral is not connected to the outdoor units. We ...
73 views

### How can I solve the following phasor analysis question?

How can I solve part B? Obviously, since the two sources have different frequencies I started off by killing the voltage source (short-circuit) and then tried to apply KCL. My goal was to find the ...
77 views

### Series RLC circuit - Phase difference between voltages across inductor and resistor is not exactly 180, why?

In phasor analysis we put inductor voltage along positive $j$ axis and capacitor voltage along negative $j$. So these two voltages are exactly $180$ degrees apart. But in simulation below, the ...
121 views

### How does a driving voltage affect an LC circuit?

I need help understanding how the drive voltage $V_d$ and the coupling capacitor $C_d$ in the circuit above affect the total energy of the LC circuit. The author arrives at the following equation ...
78 views

### CT showing different reading at phase and neutral

simulate this circuit – Schematic created using CircuitLab I have attached a simplified version of my test circuit. When the current transformer is connected to the neutral side like in the ...
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### Why use vector sum for calculating neutral current?

In a three phase system, we use a vector sum to calculate resulting neutral current. I don't understand why we use vector sum. The resulting neutral current is actually the sum of instantaneous values ...
47 views

### Combined Space and Time Phasor Diagram of a Synchronous machine

Consider a synchronous generator with its electrical and mechanical angles between them In the left diagram δ is in mechanical domain but delta is also the electrical angle between Ef and Er in the ...
55 views

### 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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### 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 ...
45 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 ...
1 vote
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### 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 ...
60 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, ...
100 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 ...
1 vote
135 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 ...
1 vote
150 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 ...
1 vote
218 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 ...
255 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 ...
3k 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? $8e^{-j60^{\circ}}$?
164 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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### 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'. ...
77 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 ...
1 vote
33 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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### 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?...
1 vote
68 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 ...
63 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 ...
182 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. ...
276 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 ...
224 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 ...
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 ...
183 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 ...
52 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 ...
237 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 ...
1 vote