# Questions tagged [phasor]

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• 83
1 vote
175 views

### How to use the equivalent circuit of an induction motor?

I have met a data sheet for a three phase induction motor intended for the traction applications. The data sheet contains below given table I have chosen the column operating point - continuous point ...
• 1,113
1 vote
240 views

### Explanation of 4-wire Delta Transformer Phasor Diagram

I have been studying some of the Tx configurations for metering. I've been looking at a booklet called the Power Measurements Handbook, which is sort of an informal resource in the metering world. I ...
60 views

### How can I find the I1 phase angle provided?

A 240/110V transformer has a no-load primary current of 0.2A. When a purely resistive load is connected to the secondary, the primary current is 1.5A. Ignoring all losses and leakage effects, find the ...
• 19
125 views

### Find the voltage and the current in the circuit

Find $v_2(t)$ and $i_5(t)$ Data: $i_4(t)= 3\cos(2t+150^\circ)$ Solution: $v_2(t)= 68.807\cos(2t+7^\circ)~\mathrm{mV}$ $i_5(t)= 2.481\cos(2t-177^\circ)~\mathrm{A}$ What I need is the ...
39 views

### Does a phasor of composite sinusoid give information?

I have a circuit with multiple supplies and each power supply has a different frequency. Would adding the rectangular form of the output give useful information about the composite sinusoid waveform? ...
• 97
1 vote
73 views

### Please explain solution (TEM waves in spherical coordinates)

I have a question and a solution, I don’t know how the solution came up with the variables and values highlighted in blue in the solution part. Question: Solution:
• 11
260 views

### Why do I get the wrong phase shift?

I am trying to compare theory vs simulation values and it seems to be that there are differences. I am using Multisim to simulate a RLC circuit, the LC are in parallel and in series to the resistor. ...
• 97
121 views

### Phasor of transfer function

Say I have the following transfer function: $$\mathcal{H}(s) = \frac{Bs^2}{a^2 + \frac{a}{Q}s +s^2}$$ I want to prove it is a Low-Pass filter. In order to do it I'd like to change it to phasor form so ...
• 1,163
131 views

### Phasor format vs time domain format question

I have a quick question regarding phasor format vs time domain format. Whenever we write in the phasor format, the magnitude that we use must be the RMS value for voltage/current, correct? Then we ...
1 vote
155 views

### Why is the instantaneous magnitude of current and voltage in a phasor diagram given by the vertical components of the phasor vectors?

In general, if a phasor is rotating, the instantaneous voltage is given by $i_m\sin(\omega t)$ where $i_m$ is the amplitude of the current. Similarly, voltage is given by $v_m\sin(\omega t)$ ...
355 views

### Phasor calculation doubles frequency?

When working with phasors we have $$\bar{Z} = A\cos(\omega t + \phi) = Re(Ae^{j(\omega t + \phi)}) = Re(Ae^{j\phi}e^{j\omega t})$$ where $$\bar{P}_1 = Ae^{j\phi}$$ is the phasor. But when we multiply ...
• 1,163
2k views

### What is the imaginary part of a phasor expressing?

Lets say we have a sinusoidal signal in the form $V = A e^{j\omega t}$ We can also write this as $V = A(\cos(\omega t) + i\sin(\omega t))$ If we plot this signal, we see the real part of above ...
• 167
408 views

### Current source in parallel with a short circuit

If a Dependent current source is placed in parallel with a short circuit, to solve our calculations would we assume that no current will flow through the dependent source and hence we remove it. For ...
231 views

### 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 ...
• 881
1 vote
204 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 ...
• 221
273 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 ...
• 1,150
254 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 ...
• 141
617 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 ...
• 2,519
962 views

### 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 ...
275 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 ...
194 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; ...
102 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 ...
• 43
800 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 ...
• 115
1 vote
205 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 ...
• 445
470 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, ...
1 vote
561 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 ...
• 33
1 vote
526 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
479 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 ...
• 173
1 vote
1k 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 ...
• 21
1k 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 ...
• 1,498
7k 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? $8e^{-j60^{\circ}}$?
• 341
380 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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329 views

• 101
1 vote
964 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'. ...
• 486
275 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
264 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!
2k 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{...
• 1,113
131 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 ...
• 197