Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

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1answer
233 views

3 Phase Dyn5 transformer neutral groundig

What happens when a Dyn transformer grounding fails? The transformer has mixed loads (1phase, 3phase) also unbalanced. It is going to act as an isolation transformer or ...? Will the phase and line ...
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2answers
111 views

Choosing equipment for 3 phase wind generator?

I want to be able to move the windmill I am designing out of the wind when the power output is to much (high wind scenario). To do this I need to measure the output of the power. To set everything up ...
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4answers
6k views

Is three-phase power in a residential building 'good'? [closed]

I live in a three story building. Last night, the top floor lost power for about 30 minutes while the rest of the building was not affected. When I asked a local electrician, he said this was due ...
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1answer
4k views

What happens when one of the 3 Phase load is disconnected suddenly?

I am sorry if I am asking trivial question. I tried to search previous questions but unable to find it, there is only question on what will happen if neutral line disconnected. My question this time ...
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1answer
669 views

How does skewed conductor on the rotor of squirrel cage decreases crawling affect?

My questions, as stated in the title, is how does skewed conductor on the rotor of squirrel cage decreases crawling affect? I've gone through articles in about cogging and crawling affect on ...
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1answer
388 views

Skew angle in 3-phase AC induction outer rotor motor

I am working on a motor like the above stated. I have 3-phase winding on a 24 slot stator. I am now designing the rotor part. What skew angle should i use for a very smooth rotational torque? Is there ...
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3answers
701 views

Are 3 single phases equivalent to a single 3 phase system?

I am not an electrical engineer (I did work as an automation technologist a long time ago, but please forgive me my electricity is very rusty). I've been given some data that was measured from a 3-...
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2answers
893 views

3 phase power to supply 3 heaters

I have been looking all over the web and finally found and joined this site to get an answer to this question. Ok, I am working on an old plastic injection machine. It has been badly abused in its 40+...
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2answers
2k views

Maximum HP of 3 phase AC motor [closed]

In my research I have found that 3 phase AC motor torque ratings are for continuous torque, but that the torque rating can be exceeded for brief periods of time. Does anyone know how to calculate the ...
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4answers
2k views

Three phase 230V input to single phase 5V/5W power supply [closed]

How can I design a 5V/5W DC power supply derived from 3 phase 230V AC input supply? My application need to work, even if, only one phase is available.
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2answers
71 views

Logging 3-phase power

I need to measure and log power, and I want to do it mostly correctly. I would greatly appreciate a listing of the errors I have made in my method. I want to measure (and log) the power output of a ...
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1answer
80 views

How can there be a non-zero voltage difference between Phase A on the left and Phase A on the right when they come from the same power source?

Hi StackExchange community, Here I have a wiring diagram that represents a portion of a circuit found in a hospital. The voltage difference was measured between phase A on the left and the phase A ...
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1answer
40 views

Power Tool Currently Hooked to 220V 3-Phase [closed]

Hello and thank you for your time on this (my issue). I was going to purchase a power tool that is currently hooked to 220V 3-Phase electric service. What would I need to do in order for this device ...
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1answer
2k views

How does three phase add up?

I understand that three phase allows you to always have a voltage, when another phase is in neutral, other phases will be at maximum peak. What I don't understand is how three phase's add up? If all ...
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1answer
114 views

What hypothesis are needed to support the following argument on a three phase system?

Given the following three-phase system: simulate this circuit – Schematic created using CircuitLab Suppose to set 2 wattmeters as follows: \$P_{21}\$ which measures current \$I_2\$ and ...
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1answer
539 views

3 phase transformer to output 2 wires

Is there a way to connect transformers secondarys so that I get only two output wires and not three(It doesent mater if the wires aoutput 3 phases or 1 phase or some wierd signal). This is step down ...
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0answers
119 views

Without converting the secondary side to “Y”, how would one solve this question?

The question: "A three-phase 230 V, 27 kVA, 0.9 PF (lagging) load is supplied by three 10 kVA, 1330/230 V, 60 Hz transformers connected in Y-Δ by means of a common three-phase feeder whose impedance ...
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5answers
1k views

Why is the Earth a useful reference of electric potential?

I may be a little confusing, but I honestly need a good help to make me understand certain things. I like very much to learn theory, but I feel that if I learn it without associating to the real life, ...
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1answer
85 views

Wind Turbine - Current vs Power trend

I'm looking at wind turbine current - power trends, and there is a phenomenon I need help to explain! The data I'm analysing is from a 3-phase generator. Below is a scatter plot of current (x axis) ...
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1answer
724 views

For a Y connection, why would a line-neutral current be the same as a line-line current?

For the following image of a Y-connection (taken from here) How would a line-to-neutral phase current be the same as a line-to-line current? Assuming I_{1N} is the phase current and I_{13} is the ...
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1answer
458 views

Rewiring AC motor with 8 wires to vfd [closed]

I am helping a friend who has an AC motor that was originally wired to run on 220VAC but from the looks it is wired to use two capacitors to (somehow) convert a single phase to a 3 phase... the goal ...
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6answers
3k views

480V 3-Phase AC to DC 12V

I am trying to figure out the best approach to convert a 480V 3-phase AC to a 12V DC. I am thinking of first converting the 3 phase to a single phase AC then using a transformer and rectifier shown in ...
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1answer
148 views

Power system analysis

I really wish if someone can help me in these three questions: three -phase balanced load has a 10 ohm resistance in each of its phases. The load is supplied by a 230/400 V three-phase source. a) ...
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2answers
409 views

3 Phase line to line voltage application

I've been tasked with designing a three phase system to be sent over to the US and have encountered a few questions along the way. My system will be hooked up to a 208Vac three phase socket and most ...
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1answer
7k views

Speed control of 3 phase induction motor using thyristor

I am working on project of controlling speed of 3 phase induction motor. To control the speed of motor I am using thyristor TYN16-600CT. As I am searching for ...
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1answer
2k views

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 ...
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1answer
2k views

Snubber circuit for 3 phase inverter designed for BLDC motor

I'm designing a motor controller for 3-phase BLDC motor. I'm using following components, Gate driver - IR2184 MOSFET - IRF540N The complete circuitry and output waveforms are available here. I have ...
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3answers
5k views

Calculating phase voltage

Lets say we have a typical automotive alternator (as shown in the picture) and we are measuring voltage between red and blue dot. How do we calculate voltage between green and red dot?
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1answer
1k views

Trying to get the Run Capacitors right for my rotary phase converter. Getting Weird Results

I constructed a rotary phase converter from a 5 HP motor. The converter converts 220 single phase to 240 3 phase. Well, it is supposed to. I am getting some very odd results that I am wondering if ...
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3answers
3k views

What are the effects of trimming the diameter of a wire down to half its gauge?

I have a three-phase, 4 AWG 259/28 stranded power transmission cable (3 conductors total) running ~200m into a slip ring. The only way to connect to the slip ring is by using its 8 AWG pig tails. ...
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1answer
362 views

Sending Voltage is higher than receiving voltage: Parallel Load Problem

I had a problem on an exam which reads as follows: At the end of the day, I got that the sending end voltage is lower than the receiving end voltage, which I know isn't possible. I think I may have ...
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3answers
1k views

Why isn't line to line voltage zero?

If voltage is measured relative to something. For instance, voltage-meters measure voltage differences not individual voltage levels, or by analogy altitude is measured relative to somewhere. Mount ...
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1answer
301 views

Soft starter design Using Back to Back SCRs three phase induction motor

I am seeking a help to design the firing angle technic of my Squirrel Cage Induction Motor Soft Starter of Back to Back SCRs. How to calculate the appropriate firing angle? and what are the wave forms ...
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1answer
315 views

How does three phase full converter work?

My question is for firing angle(alpha)=0,why is T1 triggered at 30?
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1answer
703 views

Motor wiring problem

I have a bit of a problem correctly wiring up the motor on a piece of industrial equipment that was ordered from China. When ordering I was told that it would run off of a three phase supply. I've ...
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1answer
576 views

Braiding 3 Phase Wires

I'm working in the 50V, 10A range with un-shielded wire to drive a brushless DC motor. Are there any advantages to braiding the 3 phase wires? will it reduce EMI and spiking?
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0answers
57 views

Can a phase converter convert from DC

Can a phase converter (1 to 3) convert directly from DC to three phase or does it have to invert it to AC first then convert to three phase?
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1answer
1k views

Grounding of one pahse of a starpoint where the point is not grounded

Note: This is just a thought experiment. What would be the effect on a three phased system if one phase of the star-point was grounded with no other ground connection in the system? In other words: ...
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3answers
374 views

Neutral-Phase reversal

Could anybody suggest solution for a situation where, In a 3-phase, 4-wire system, phase and neutral are getting interchanged. How can I prevent this situation and what is it exactly called!?
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2answers
5k views

Controlling three phase heating element

I am building a small brewery and would like to heat a barrel of aprox. 280 liters of water with an three phase heating element. Its power would be 15 kW. That means that connected to 400V the full ...
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1answer
4k views

How to wire a three phase bridge rectifier

I am doing a DIY three phase AC motor power generation project. I can understand the basics of electronics, and also understand how the wires are wired in a single phase rectifier. However, for three ...
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2answers
293 views

Is balancing the only mechanism that regulates the phase currents in a three phase system?

Here is a basic illustration of a distribution system: In a 3-phase AC system, phases cancel each other out, leaving only a small imbalance current and this is fed to earth at the substation. That is ...
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2answers
1k views

Unbalanced three phase system with unbalanced phase to phase voltages

I've got quite a problem here trying to solve this 3 phase system (2nd U12 should be U31) and hope you can help me: I'm trying to calculate the single phase voltages and currents for the drawn case ...
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1answer
133 views

Add harmonics to Clark and Park

I have a problem with adding harmonics to park-clark transformed 3 phase value. Here is transformations I'm using: ...
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1answer
114 views

Voltage Sequence in Three Phase System from wattmeter reading

How does one identify the phase sequence of voltages in a balanced 3 phase system solely from the readings of two wattmeters connected properly to measure total power? I am referring to the two ...
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1answer
2k views

DIY Rotary Phase Converter with starter motor, cutout relay in parallel with load?

I am working on a DIY Rotary Phase converter with pony motor. This will use single phase 240v and run capacitors to feed 2 legs of a 3 phase motor, which will generate the 3rd leg. It uses a 1/2 HP ...
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3answers
4k views

Maximum resistive load on 3 phases 400V, 16 A

I have several resistive heating element and I want to draw the maximum power from a 400 V, 3 phase, 16 A socket. If I design the heating elements to connect between phase and null = 230 V RMS * 16 ...
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4answers
4k views

3-phase regulated “ideal” rectifier

In motorcycles broken stock voltage regulator is a very common issue. Stock solution is SCR based and commonly burns due to overheat/ SCR failure. DIY regulators usually have the following design (...
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2answers
1k views

Simple 3-phase generator

I was reading an answer in Quora about how 3-phase electricity is generated. There was a picture in the answer: Is it right to say that the generator above can produce 3 oscillating currents with 120 ...
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1answer
60 views

3-phase power: getting incorrect phase

Here's my working: $$ V_P = \frac{V_L}{\sqrt{3}}$$ $$ \therefore V_P = \frac{21.651kV}{\sqrt{3}} = 12.5kV$$ $$ S = 3V_PI_P$$ $$ \therefore I_p = \frac{S}{3V_p} = \frac{2400+j1800kVa}{(3)(12500)} = ...

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