Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

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1answer
447 views

Making a three phase voltage source to drive a gyroscope

I'm trying to drive a gyroscope that needs a 3 phase 400Hz 32v 1A power supply. How can I provide that supply? It's one part of my university project and I'm a beginner in this field. I'd like to find ...
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1answer
483 views

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 ...
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1answer
542 views

Disconnectors Symbol in Single Line Diagrams (SLD)

where should the moving part of a disconnector be located when breaking gets applied, on the energized side or on the disconnected side? Is there any standard?? Suppose a non ring, simple grid and ...
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2answers
1k views

3-phase Inverter in single phase operation

I'm working on a standard (AFAIK) 3-phase, 6-pulse inverter. I'm testing it under single-phase conditions to see what the de-rating will be. My understanding: With everything else staying the same,...
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2answers
3k views

Three-phase rectifier circuit simulation

Is this the correct way to simulate a three-phase full bridge (6 pulses) rectifier? I ask because I have tried this first without the two capacitors, just one, and the capacitor seems to have ...
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2answers
38k views

Run a 3 Phase machine, on 240v with start & run capacitors [closed]

Being a Carpenter & Joiner, I must approach "cap in hand" and ask some proper sparkies for assistance in pointing me in the right direction please? Maybe someone could take a look at the wiring ...
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1answer
1k views

Use CT current sensor to measure AC current of a single device

So I recently bought 3 current transformers with the goal to measure the current of 3 washing machines. All I want to measure is if the machines are running or not so accuracy isn't really a concern. ...
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3answers
13k views

Is it possible to convert 3 Phase 220V to 110V without use of a transformer?

I am living in an area where line voltage is 220V. If I have access to all 3 phases, is it possible to create a "socket" with output voltage of ~110V, without use of a transformer? This is primarily a ...
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1answer
310 views

Help with a full bridge three phase rectifier powered floor

I originally posed a question here asking about solutions to power a small rover 24/7 from a powered floor. It seems the best solution is a full bridge three phase rectifier circuit. I have a few ...
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3answers
13k views

How is transition from three-phase distribution without neutral to three-phase consumption with neutral achieved?

A typical distribution grid supplies 6 or 10 kilovolts AC to a substation near the consumers. This is typically done with a three-phase line without neutral - just three wires going in parallel. Then ...
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0answers
79 views

Rotation-switched active rectifier idea

Most of you will know how three-phase rectification works and how cool it is. My idea is: replacing the diodes in a three-phase full-wave diode bridge with MOSFETs, as in active rectification, and ...
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5answers
123k views

Three phase power supply - what is line to line voltage

Well this seems like a basic principle, yet I can't seem to get it. (We're expect to "know" this already). In a three phase situation I'm given a source voltage of 230V. - So the waveform of each of ...
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1answer
1k views

What determines what type of short-circuit current is highest?

I'm doing a short-circuit analysis of a system, and started wondering about the following: What determines which type of fault current is the highest (and lowest)? The screenshot below shows the ...
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2answers
390 views

Powering Several Electrical Components from Single Three-Phase 240V AC Supply

A system consisting of various electrical components is desired. Required supply voltages to power these components include the following: three-phase 240 V AC (directly through the supply), 24 V DC, ...
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3answers
3k views

Finding frequency of a three-phase generator from phase voltages

I'm trying to find frequency (i.e.; rotations per second) of a balanced three phase generator. Output peak voltage of the generator goes up to 150V. One solution I found is to attenuate rectified and ...
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0answers
231 views

Missing phase 3-quadrant TRIAC-based solid state relay for 3-phase engine

First of all, I'm a simple mechatronics technician student first time posting here, so please don't mind if I say something that seems completely stupid, since I consider myself to be a total newbie ...
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2answers
4k views

Three phase rms voltage calculation

I am new in instrumentation and control. I am developing a hardware for a project and the following is my application. I have three phase stepped down voltages and stepped down currents entering my ...
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5answers
63k views

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-...
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1answer
885 views

Obtaining three different DC voltages from a three-phase AC supply

I have three identical sinusoidal voltages, R, S and T, whose phases are spaced by 120o difference. I want to obtain three different DC (unfiltered) voltages from these tree AC signals for some reason....
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3answers
26k views

Calculating phase currents and neutral phase current

I am doing a homework that I got yesterday and it concerns calculating phase currents and a neutral phase current. 3 phase it is. Three individual charges, each on their own phase and a shared 3-phase ...
4
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4answers
3k views

Control torque of 3-phase AC motors

Actually, we have 1x30HP, 2x10HP motors working at our workplace. When we start the motors there is a lot of torque generated due to which our grid supply charges us penalty every month. We need ...
2
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1answer
712 views

Is there a rectifier scheme for tri-phase which is more efficient than the bridge rectifier?

Because of the topology of tri-phase bridge rectifier, every phase is active (i.e.; feeding the load) only for 33% of the time. It feels like we are not fully utilizing all the three phases, and ...
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1answer
877 views

Three Phase to single phase [closed]

I have 1Kw supply of three phase in my home. I need a single output of all three phase and neutral. E.g If I connect 1 equipment of 600watt 15 amp single phase, now I want equal load 200watt 5 amp on ...
4
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1answer
221 views

Obtaining DC from a tri-phase generator

I have a tri-phase generator which outputs AC voltage waveforms (\$R\$, \$S\$ and \$T\$) with 120o phase shift between them. I want to rectify these voltages and obtain a single DC voltage. I ...
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2answers
6k views

General 3 Phase Motor Inductance Question

I know that motors are inductive loads. Does the inductance of a 3 phase motor depend on the load on the motor?
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1answer
239 views

Can a 3-phase rectifier handle input from a 1-phase/2-phase source?

In trying to homebrew a miniature wind-turbine using the stepper out of the tray motor from the CD Drive (sloth that I am) I'm loath to go to the effort of constructing a rectifier, and a regulator. ...
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3answers
80k views

difference between single double and three phase

If single phase is 230 V and 3 phase is 440 v then what about for 2 phase? And why is it so?
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0answers
134 views

Faulted phase detection

Currently I am studying about short circuit detection on long lines and I can't solve one task: I have line between two substations, and there is short circuit some where on this line. I know current ...
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1answer
83 views

Any Ideas for Understand one of the 3 phases has powered

I want to ask you about a situation which i couldnt find the exact solution or better way to do the job. The situation is i have 3 phase (380V) induction motor and one of the phases to the motor had a ...
3
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1answer
1k views

How calculate three phase kilowatt hour from time sampled data of voltage and current of each phase

My problem is I want to calculate three phase kilo watt hour from time sampled data of current and voltages. My doubts 1) How can I calculate the kilowatt hour from time sampled data? Is it any ...
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2answers
879 views

Do I have pseudo three-phase power at home?

I get three live wires and one neutral from the mains. Different rooms in the house are connected to different circuits which terminate at a changeover panel. The changeover switches allow each ...
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1answer
3k views

Why is using a single phase device across phases of a 3 phase outlet OK?

My friend connected two wires to two "non-earth hole" in a 3 phase outlet (208V) to run a 220V single phase blower (Note: the outlet has four holes, one of them is earth). Basically, he used the ...
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1answer
1k views

Ground Fault Question Regarding a 3 Phase Circuit

I'm needing to design a 3 phase ground fault detection system for a 480V system. It will need to be able to trip when there's ground fault current >1A. I have done some reading and it sounds like ...
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1answer
40k views

Why does a 240 volt outlet save money in electrical cost than a 120 volt outlet?

I live in the US and we have many outlets that run at 120 Volts. I heard that for devices that support the 240 volt standard may not cost as much in electricity prices. Can someone explain how by ...
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2answers
10k views

3-phase power calculation when phase to phase voltages are different

I have a 3-phase power supply rated at 230VAC per phase. However, the phase to phase voltages are not equal. Suppose \$V_{RY}\$, \$V_{YB}\$ and \$V_{BR}\$ be the three phase-to-phase voltages between ...
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1answer
289 views

Terminals of three phase power machine

A three phase machine, instead of having six terminals, two for each slip ring, has only four terminals. Because the starting point of all the three coils have a common junction which is usually ...
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1answer
932 views

How to measure phase angle of 3 phase by microcontroller [closed]

I am currently using PIC18F452, trying to measure the phase angle of 3 phase. How can I measure this. What feature of PIC can I use to solve it.
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1answer
67 views

Searching for phase change device

Anyone knowing of a module that can monitor three incoming electrical phases to a home. If the load goes over a certain maximum, the device changes to one of the other phases for supply to e.g ...
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3answers
2k views

drive 3 phase induction motor with only DC (not pwm) thru each phase

I've been researching making a driver for a 3 phase induction motor powered by DC source using PWM to approximate sine waves in each phase. However, the switching speeds of the PWM signal for the ...
5
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6answers
2k views

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 ...
2
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1answer
1k views

3 phase induction motor with one phase [duplicate]

Possible Duplicate: 2 Phase to 3 Phase conversion Is there a way to run a 3ph induction motor with one phase . Basically I have 3ph motor but my power supply is only 2 phase . Is there anyway I ...
10
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3answers
15k views

Single-phase to 3-phase conversion

I have seen some boxes (with some capacitor circuits inside) which do single-phase power supply to 3-phase power supply conversion. The problem with them is that they cause the load motor to heat up, ...
3
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3answers
784 views

IC for converting single phase to three phase

I want to design a device to control a 0.5 HP to 3.0 HP three phase AC motor with single AC power. I need to able converting single phase to three phase. Also an three phase ac motor controller ...
3
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4answers
719 views

3 phase computer chip

I have just had a conversation with a friend who studied quantum computing. Sadly I have forgotten most of the conversation as it was far beyond my knowledge threshold. Essentially he was saying was ...
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6answers
56k views

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 ...
5
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1answer
5k views

Switching a 3 phase pump using a solid state relay

I made a remote (GSM) controlled module for a 3 phase pump close to my friends house. The pump should run at night, and walking the 1km to the switch while they are sleeping is the problem. The ...
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1answer
221 views

Circuit for switching higher load using transitor with signal being 300 Hz PWM

EDIT: DO NOT even think about using the naive example of a circuit to switch three phase. As someone rightly pointed out this is a complex issue and will almost certainly result in burnt finger or ...
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3answers
73k views

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 (...
3
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1answer
1k views

What is the current limit on each phase of a 160 kVA three-phase UPS?

I'm a physicist by training, so I think I understand voltage, current, phase and power. However, I lack the knowledge to translate between this and the published ratings on three-phase electrical ...
5
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2answers
1k views

Unknown motor, specifications interpretation and use

I got a motor on the picture. Does anyone know what it was used for? My main question is if is it feasible to use it as a barbecue motor or is it too strong? Can I connect it to one or three phases ...

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