Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

Three-phase power is commonly used in power generation and distribution, as well as to drive industrial-sized motor loads. Most residences do not have three-phase power. Loads and transformers can be configured as line-to-line (delta) or line-to-neutral (wye).

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Y or Delta connections advantages / disadvantages

I have been studying three-phase systems for the whole course of a subject (on the first year of the university degree). I have finished now, and I know both "Y" (star) or "Delta" (triangle) connections. I have made a lot of computations with them,…
user3780731
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Is there a convention for the ordering of phases in three-phase power in the US?

I recently moved my small machine shop to a new location. Both locations had 3-phase power, and I wired up a 3-phase air compressor in both locations. In both locations, I used the convention of black-red-blue wiring on L1-L2-L3 bus bars in the…
Rick
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3-phase explanation

I have been reading about single phase and three phase power. I'm completely confused now. Can someone please give me a working example of when I would use three phase power instead of single phase (some sort of common situation I could relate to)…
Baldrick
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Determining phase sequence in software

We have 3-phase electric network. How to determine phase sequence (L123 or L132) from 2 line-to-line voltages U12 and U32? I prefer computationally simple solutions. Is it possible to determine phase sequence without computing phase voltages (which…
truthseeker
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Unbalanced three phase system - Neutral fails/opens/disconnects - consequence?

I have a very basic question about three phase system. I am not an electrical engineer hence I might not have a good understanding of the subject. So, please be bit lenient in answering and asking clarifications. My home receives a 220v (between one…
Narayanan
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Phase Voltage Confusion

Here's a question that I was asked with the answer keys. From the problem I deduced the net load impedance for one of the elements in the delta configuration will turn out to be 172.767|_3.66194 Ohms. Assuming that the voltage and current will be…
Nick Yarn
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Per Unit System: what details am I missing

Ok, so I had a problem about a three-phase system with the following data $$V=220kV$$ $$S=150MVA$$ $$\cos \phi=0.85$$ where V is the phase-phase voltage, S is apparent power, and \$\phi \$ is positive (inductive load). Ok I was asked to find out…
Granger Obliviate
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Balanced three phase circuit Y-Y with neutral

Here is my equivalent balanced three phase circuit Y-Y with neutral: Rla + jXla is my line impedance by phase. L1 and L2 are my loads. The exercise is saying that L1 absorbs 180 W and 240 VAr, L2 absorbs 600 VAr and has 0.6 lagging power factor.…
João Paulo
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Three phase heaters and amps

I am a mechanical engineer with basic understanding of electricity. I am programming an app for ordering 3 phase heaters, and I have an argument to resolve with a coworker. Lets say I have a 208V 3-phase heater (delta connection), with a heating…
PMay
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Determining the order of succession for a 3-phase current

On some exams the following question appeared that I am not capable of answering: How to determine the order of succession of the 3 phases of a 3-phase power using as a load either: a) 2 lamps and 1 coil or b) 2 lamps and 1 capacitor. I guess it has…
Eypros
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Problem understandin per unit system

I having trouble understanding PU system especially "briding" the gap from PU system -> to Actual system To illustrate this here is an example where I am given the one-line diagram for the three phases system: The first objective is to find the…
FluidProblem
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Millman's Theorem 3-Phase, 3-Wire, Star (Y) Unbalanced Load

So I missed the lecture we had on Millman's theorem and I have tried to do a bit of research on it but I find several different versions of it. I have tutorial papers to do but they work on the basis of you knowing how to do them already basically…
Ryan Walkowski
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Why can't I find Phase to phase voltage like this

I know that that in 3phase ac, Vll = sqrt(3) * Vln I got confused about the sqrt(3) part so I draw phaser diagram and the resultant vector will give me the phase -phase voltage But it only gives me 230V , why? Can anyone explain how it got…
Athul
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Three phase system - power factor

I need help with the following problem: Given symmetric three phase system (see attachment) of phase voltages with angular frequency ω=100rad/s, R=5ωL=100Ω. Find capacitance of capacitor C such that the power factor of three phase receiver has…
user300048
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How to determine phase angle of a three-phase circuit

I am experiencing difficulties with a question: A balanced three-phase load shown in the diagram is connected across a 380V, 50 Hz three-phase supply, ABC phase sequence. The voltage VAB is taken as reference. Part of the question I am trying to…
n0t_a_nUmb3R
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