Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

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2answers
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Why is neutral required in three phase charging of Electric vehicles?

Talking about both three-phase AC as well as DC fast charging (wherein 3 phase AC is converted to DC) in EVs, I think that the 3-phase rectifier represents a balanced 'load'. Therefore I want to know ...
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67 views

kVA calculations

For electrical panels / systems with three phase electricity (red, yellow, blue) ~220/127. When using line to line we get 220 V is this considered single phase system or three phase? I know three ...
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1answer
107 views

Calculation of 3-phase power in Electric Vehicle Charging

I have a doubt regarding calculation of 3-phase power in EV charging. On the last page of the pdf in the link given below, the power calculation is done as 3 x 230V x 16A = 22kW. http://www3.fronius....
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113 views

Drawing power from only one phase of a 3 phase alternator

Note: I am busy learning about 3 phase alternators. A lot of my understanding is theory so I'm running through scenario's for better understanding. Scenario: Lets say we have a 2KW-220V-50Hz 3 phase ...
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1answer
330 views

Voltage between phases of 220V 3-Phase Generator with no neutral

I'm looking at a 220V-50Hz 3phase generator which has no neutral wire and 3 live wires. Am I correct in assuming that the voltage between phases will be 220V for this generator?
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1answer
330 views

What is the most efficient 3-phase to single-phase AC transformer for a home grid

So a friend of mine is getting electrical power installed for an urban site he bought, and I'm just trying to be a good friend by looking into this. The company doing the installation recommended he ...
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3answers
2k views

How are the individual homes connected in a 3 phase power distribution system (power grid) so that they have correct voltage?

For a single phase distribution system it's simple, each home has one wire coming from the neutral and one from the live, in turn each outlet has a live and a neutral wire. The live is 120V relative ...
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1answer
105 views

For induction motors, would one expect harmonics to be different between Delta and Y stator windings?

Given two induction motors with the only difference being that one is wound delta, the other Y, would I expect to see a different behavior if the source is a three phase voltage with harmonics?
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638 views

How does 3 phase AC generate more voltage than single phase? Aren't the wires connected in parallel?

If you connect two voltage inputs in series it results in a higher voltage, if you connect them in parallel it creates a higher capacity / max current, but voltage is unaffected. If you use 3 plugs, ...
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2answers
707 views

Why is the torque vs slip speed characteristic of an induction motor costant with respect to the frequency of the voltages applied?

I'm currently studying the induction motor and I have some troubles to understand which causes this thing. Let $$w_2 = w_1 - w_r$$ be the slip velocity and $$s = w_2 / w_1$$ be the slip, where w_1 is ...
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3answers
735 views

Current Transformer (CT) and Potential Transformer (PT) Sensors - How to Measure Electrical Power Usage?

I am not from Electrical Engineering background and so, does not have much idea about how energy power meters work. I want to measure electrical power usage of a three-phase induction motor. So, I ...
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3answers
445 views

How can a three-phase motor have 20 Nm of torque at 1432 RPM and 1.8 kW?

I am trying to work out the maximum torque a motor puts out to do some stress analysis on a structure, and I have just been given the motor details from the manufacturer. They said it produces 20 Nm ...
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1answer
350 views

BLDC phase voltage wave form

I am measuring the phase voltage of a BLDC motor as shown in the figure below. As the motor doesn't have neutral point, a virtual neutral point(VN) is created by the resistor network and three-phase ...
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3answers
90 views

Another question about power to homes in Europe

I have a couple more questions about power to homes in Europe. Our device draws between 12A and 45A (at 230vac) depending on its configuration. It appears that at the high end of the scale that will ...
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0answers
262 views

Can i use Three Phase to single phase transformer to power SMPS?

I'm having trouble understanding the part related to power and its calculations, sorry for my ignorance. I have a three-Phase 380Vac System with no Neutral wire available and i need to power the ...
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1answer
366 views

Confusion with applying KCL to three phase delta connection

Below is a 3-phase delta connected for balanced loads Z: Since phase to phase voltages(voltage across loads) have 120 degrees phase differences and since the loads have the same impedance we can ...
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1answer
311 views

One phase,two phase and three phase

I tried to make a generator for the course assignment. I am confused in the phase connection in the generator. what is the difference in one phase, two phase or three phase generator connection??
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1answer
651 views

Why 3 phase is preferred over any other phase power transmission? [duplicate]

Why 3 phase is preferred over any other phase power transmission ? My instructor was explaining this topic in my Electrical machines class. And he mentioned the following points In single phase, ...
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3answers
20k views

Three 1 phases vs one 3 phase power cost

Case1: If I have three single phase connections with each having its own single phase energy meters And I connect 1kw load on each of these phase continuosly 24/7 for a month. Case2: Now next month ...
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2answers
7k views

How do 3-phase dual voltage motor windings work?

Many 3-phase motors allow for two possible line voltages, for example 230/460. I am trying to understand how the different wiring is changing the way the windings get current. I would guess that ...
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1answer
2k views

Running a 3ph motor rated for 380v star on 220v delta

I've got an old Soviet 4kW motor, made in 1983. The dilemma is that the nameplate info states a Y-connection/380v/8.7amps and I want to run it on delta using my VFD which produces 3ph 220v. All my ...
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1answer
91 views

How do we design a control system with a mix of single-phase and three-phase electrical loads from a three-phase supply?

I have connected a three-phase incoming power to a MCCB, MCCB will distribute to a 3-phase transformer as well as few single phase equipment, which is means outgoing of MCCB L1, L2 & L3 to ...
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470 views

Two 3-phase generators in parallel

I need to calculate the PF of supply V2, a 3-phase generator that is operating in parallel with another generator (11kV star-connected). Both the generators are equally sharing the mechanical load of ...
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0answers
3k views

3 phase transformers and equivalent circuits

There is an exercise in my textbook that goes like this: 3 single phase transformers are connected in wye-delta configuration. Each transformer has the following parameters : R1, X1, Rc = \$\infty\$, ...
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2answers
591 views

Find primary current in 3 phase transformer

I am really confused with the above problem. I get the logic of the solution Since,the line voltage ratio is 2. So, current will be half. Thus 50. But I am confused should we take +30 or -30. ...
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0answers
104 views

Can we assume 230VAC in 3 phase system between phase and neutral?

If all devices connected to a 400V 3 phase power system are balanced and have a perfect power factor, can we assume the voltage between each phase and neutral is 230V? Why: I want to measure real ...
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1answer
111 views

Does using electronics with poor power factor affect the pulse power capability of a generator rated for a certain KVA?

The situation is such: There is a multi-pole, three-phase, permanent magnet generator (rated for 100 KVA, let's say) that feeds into a simple diode rectifier with a capacitive/DC Voltage load (...
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1answer
59 views

3-phase system with 3 loads instead of 2?

Hello, Most examples on the internet and in my text books contain 1 load with 1 source. I have yet to come across an example with 3 loads. Is there a way of combining the loads?
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2answers
218 views

3 Phase Input Power

I have a 3 phase switching power supply that I am trying to calculate the maximum input power. It is hooked up to a 3-phase, 277/480 VAC power source. The sticker on the power supply says: "INPUT : ...
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1answer
2k views

3-phase 200Vac rectifier output voltage

I was studying about 3-phase power supplies. After going through several searches, i found this formula of three phase bridge rectifier's output voltage: Vdc = ( 3 x sqrt(2)/pi ) x Vrms Vdc = 1.35 x ...
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1answer
75 views

3Phase + Neutral, 208VAC distribution and conversion to 1Phase 120VAC

Question 1: How to convert 3phase+Neutral 208VAC supply to 1phase 120VAC? Can I tap off one (any) leg of the 3phase supply and use that to Neutral to get the 120VAC? Or do I have to use all three ...
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1answer
985 views

Please explain the terms line voltage, phase voltage, line current and phase current in a 3-phase circuit [closed]

I have searched online for an explanation of these terms and was unable to find a clear enough one. Request you to explain with reference to the images below: Thanks
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2answers
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How are load currents balanced in a distribution system?

Below I drew a simplistic view of a distribution transformer which supplies a particular public area for example some households and shops ect.: Va, Vb and Vc are three phases(line voltages) of the ...
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3answers
2k views

A basic question about load balancing and power factor correction in three-phase systems

I know basically about phasor representation of line voltages and active reactive power concepts in three-phase systems. But what I'm wondering is the reasons of two things I hear a lot. 1-) What is ...
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1answer
442 views

Calculate Inductance of a three phase transmission line

I was trying to solve the above problem. As I have done many similar problems, I attempted it in the following way But I was shocked when I checked the solution given in my workbook. Please help me ...
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1answer
125 views

convert capacitor motor to three-phase

I've been given a bench grinder (rated for 150W @ 230V), which uses a (psc motor?), just an induction motor with start/run capacitor/winding (it has no centrifugal switch whatsoever). I always wanted ...
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1answer
5k views

How to calculate GMD and GMR?

The above image is from my class notes. I am not able to understand the concept of GMD and GMR calculation. While practicing, I came across the below problem Now I am not able to understand how the ...
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1answer
176 views

Calculate inductance for 3-phase double ckt line

I have attached the problem with the solution given in my workbook. I attempted the problem and ended up getting a different answer. Is my solution wrong ? Please help me to understand the problem.
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0answers
143 views

2-phases connected to single rectifier

I have come across an unusual part of a circuit that I hope someone could shed some light on and I have redrawn in LTSPICE. The circuit is to measure voltage of a 3-phase generator. Two of the phases ...
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2answers
188 views

Industrial contactor frequency influence

I'm thinking of using industrial motor contactors at the output of a 3-phase electrical generator. An example here : CONTACTOR DATASHEET The only difference / problem is that the electrical ...
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2answers
2k views

Drive voltage vs phase voltage of a BLDC motor

Background This video on using an oscilloscope to view the line-to-line phase voltages of BLDC motors demonstrates the "virtual" ground necessary for such measurements. I understand this idea: you ...
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4answers
167 views

Does this type of Dual Voltage AC Drive exist?

The goal is to run a 3ph AC motor with either high or low voltage inputs. The motor would be wired for a specified voltage and the controller drives a single output regardless of the line voltage. I ...
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1answer
253 views

Can a triphase current regulator be used with just two phases?

My house is located somewhere with power problems, these have been going on for 15 years and will probably never be fixed. Family lives next door and I want to regulate the power to both my house and ...
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1answer
34 views

Can I share a 3-phase motor branch with a small single phase load?

I have a 15hp 3-phase motor on a 50A 120/208 wye circuit. I also have a small 1A dc motor with controller and some monitoring circuits - this secondary system needs 24vdc and 1.5A altogether. I ...
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3answers
451 views

why we say that in three phase system total power delivered to the balanced three-phase circuit is the same at any instant

My question is: why we say that in three phase system total power delivered to the balanced three-phase circuit is the same at any instant?. This is how I understood that one phase at one point of ...
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1answer
198 views

Power consumed by the Resistive load

I am really confused with the above problem. I can also solve the problem taking an AC supply across a 20ohm resistor and end up getting like P = 100^2/20 = 500W I am not able to digest the solution ...
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1answer
433 views

Three phase converter - capacitor switching

I've started building a single to three phase converter. My research started with the likes of this paper. I've set a bank of 40uf/440v capacitors up and a potential relay. The relay is a Supco SUPR. ...
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1answer
191 views

Converting 110v at 8.5 amps to 208 three phase amperage [closed]

I have some equipment that uses 8.5 amps and 1050 watts on a 110v. Any idea what the amperage would be on 208 three phase?
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1answer
4k views

Is it possible for 220V to have three phases? [closed]

So, is it possible/does it exist that 220V has three phases?
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1answer
963 views

Problem with BLDC motor drive using PWM

We are trying to speed control a BLDC 48V 500W hub motor using hall sensors. We are using IRF540N MOSFETs with IR2112 gate drivers and Arduino as MCU. We implemented the 3 phase inverter and in ...

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