# Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

436 questions
355 views

### An overseas company is making a machine for me and they need to know whether I want 1,2 or 3 phase and what voltage

I'm in Quebec and the company making the machine is in China. The machine is an industrial sized T-Shirt sublimation machine that does two sided printing. So there's a large heated plate that is ...
23 views

### Transformer Sizing with Mixed Loads (Three-Phase & Single-Phase)

I am trying to size/validate the rating on the medium voltage main transformer for an industrial plant. For some reason I can't find many resources that indicate how to properly do this when you have ...
352 views

### How to design a 3-phase resistive load bank?

We are trying to design a 3-phase resitive load bank to test some step up transformers. We are receiving 3-phase 208v and stepping up to 3-phase 600V with 3-step up transformers wired in delta. Its a ...
350 views

### Why use a star or delta connection instead of having a second output

I am winding my own small three phase ac alternator and have learned about star and delta connections. Should I use 2 three phase rectifiers to turn the current to DC or only one with a star ...
97 views

### Can a Variable Frequency Drive convert standard wall outlet (120V/15A/single phase) to ~220V 3 phase?

In my workshop I have a device that requires 220V 3 phase power, with a requirement of up to 1.5kVA. In North America, my wall outlet provides ~120V/15A single phases. (EDIT - my device can take +/- ...
59 views

### Identifying direction of rotation for a three phase motor, without applying three-phase power

Suppose I have a typical smallish (say, <3kW) three phase induction motor. Likely 400V star-connected, but methods that work with any motor would be preferred. I can ensure that the supply phase ...
621 views

### Does the neutral wire have any voltage?

In this article, the author talks about 3 phase and the magic of a missing neutral wire. And there's the following paragraph: In a 3-phase system the voltage between any two phases is 3 times ...
101 views

### AC water turbine

I am trying to use a water turbine from China to charge a lithium ion battery. The water turbine is rated to 10 watts. I figured that should be enough to charge the battery but I can only ever get ...
110 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 ...
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 ...
1k 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 ...
161 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 ...
53 views

### How to detect the phase sequence of a 3-phase ac (R-Y-B or R-B-Y) using Atmega32?

I am using an 8-bit AVR microcontroller in my project to detect the phase sequence of a 3-phase AC supply. Which method shall I use to do the work with the least number of components required along ...
3k views

### 32amp single phase or three phase [closed]

Sorry if there is a straight forward answer but my partner has converted a trailer into a drinks unit. She has a fridge a freezer and a coffee machine. Also about 5double sockets and lighting. The ...
335 views

### 3 phase BLDC sinusoidal drive using PWM controller and/or DSP?

My background is mechanical engineering (robotics). I apologize in advance. I have a sensitive torque ripple (Vibrations) application and would like to use sinusoidal drive to run a 3 phase BLDC ...
117 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 : ...
43 views

### Problem with Line to Line Voltage Output in 3 Phase Inverter MOSFET Bridge Circuit

I have a problem in my 3 phase inverter circuit output. Below, i've attached an image of my circuit. As you can see, i have 3 outputs. There are R, S, and T. So, i've measured line to line voltage ...
242 views

### Question about per unit system

I have a set of impedance values for a motor referred to the stator given in per unit where: Vbase_s = Stator line to Line Voltage Pbase_s = Motor rated power Zbase_s = Vbase^2/Pbase Now I want to ...
87 views

### How to verify if all 3 AC phases are in order? [closed]

We have 220V main lines where we currently live and we have a 3-Phase connection. We have an Air conditioning unit that requires 3 phase AC input with the correct phase sequence. If the phase ...
4k views

### How does a three-phase transformer work with phases sharing a common core?

Google search reveals a lot of pictures of three-phase transformers. Looks like a common setup is to have three pairs of winding and a shared core. The core typically consists of three "bars" in ...
42 views

### Does a 3-phase VFD work if one phase is reduced (e.g. with a dimmer)?

If you have a 3-phase VFD running a 3-phase motor, and you use a leading or trailing edge dimmer on one or two of the input phases, will the VFD continue to operate normally, pulling more current from ...
56 views

### 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....
42 views

### Is a load bank always 3-phase or is a 4-phase possible?

I am designing a low voltage installation and the customer asked for a cell for a load bank. Now he drew this in 4-phase, but I did not encounter this before. Is this possible? I thought they were ...
34 views

We're in kind of a bind at work and looking for easiest / cheapest way to load an AC generator (Synchronous permanent magnet machine). We have access to a big 300A Mosfet module along with it's ...
34 views

### PWM phase voltage and current measurement for power consumption calculation for a BLDC MOTOR

I have been trying to log both voltage and current from the battery of an electric two wheeler for finding out efficiency at inverter, battery level.
76 views

### Figuring out neutral and earth in a three phase connector?

I’m trying to check whether the earth and neutral is connected correctly in a 5 pin connector which has 3 pins for lines, one for neutral and one for the PE earth. 3L-N-PE type connector. For some ...
732 views

### Line voltage and phase voltage question

​ In the question, why couldn't I just find Line current from Line Voltage? Is not Line Current=Line Voltage/Impedance? I know line voltage and line current aren't in phase, that the angle between ...
228 views

### How is Line and Phase Voltage the same for a Delta connected system?

I am having a little bit of confusion for some reason understanding how the phase and line voltage can be the same for a delta connected system, i understand why the current is different for the phase ...
56k 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-...
64k views

### Why are the letters U, V and W used in AC motors to represent the windings?

I am connecting up an AC motor and was wondering if this labeling system was representative of something? Or just another set of letter like X,Y,Z? I could not find any information regarding this in ...
45 views

### How to create EMI/EMC noise for testing product behavior in noise environment?

We have product which works on three phase AC supply. We were facing issue on I2C interface of external RTC due to noise from external environment. After some inspection, we realized that because of ...
40 views

### How to calculate R for an AC load on a 3-ph system

I'm trying to calculate the resistors in an AC dummy load for a 3-ph system. A simplified schematic can be found below. The idea is to switch (with regular AC 1-ph contactors) some resistors on each ...
62 views

### 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 ...
48 views

### How does torque control work in three phase motors?

For a project I am working with a three-phase AC brushless motor, connected to a motor driver. The driver allows digital control over the motor in position, velocity or torque modes. Below are a few ...
99 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 ...
143 views

### Find transformer leakage reactance

For the short circuit test of a 3 phase transformer (star-star connected) I am given ( or have already calculated from previous questions) $$I=9720 A\\cosφ=\sqrt 2/2\\P=300kW\\R=0.001 (phase)$$I am ...
114 views

### Generated current in a $3\times450$ VAC $60$ Hz $1150$ kVA generator

Let's say I've a $3\times450$ VAC $60$ Hz $1150$ kVA generator. How much current will there be generated when it runs at maximum capacity? MY WORK: The total Active power over a three-fase ...
384 views

### Power System Faults Problem

A sustained three-phase fault occurs in the power system shown in the figure (See Link). The current and voltage phasors during the fault (on a common reference), after the natural transients have ...
57 views

### Circuit for Neutral point of 3-Phase mains

I wonder if the 'Neutral Point' as mentioned in the attached image is correctly labeled or not? Is there any mistake in this 3-phase circuit design? Edit 1: Also it looks like the 'Neutral point' is ...
150 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 ...
58 views

### 24V, 3 Phase BDCM Controller Schematic

This may seem like a dumb question, but does anyone have a schematic for a BDCM controller. All I seem to be able to find are partial schematics or schematics that include a micro controller. My ...
68 views

### DIY 3-phase fast linear actuator

I have a need for a FAST linear actuator of which I may control position and speed reliably. I have already been looking into pnuematics, however it does not seem that this will fit my needs (I am ...
138 views

### IR2301 HO output staying on too long

I'm trying to make a 3 phase motor controller with IR2301 and IRFPC50 MOSFET. I connected everything according to IR2301 datasheet. For capacitors I’m using 10 uF (between VCC and GND) and 2.2uF (...
59 views

### Two level Inverter [closed]

What thing determines a 2-level and 3-level Inverter as in the diagram? edit: Level is as in 'voltage level'. I have found following good link that explains it. http://www.elkraft.ntnu.no/~richardl/...
147 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??
43 views

### 3 Phase vs line to line [duplicate]

Say I have the following three phase wye configuration: Source Let’s also assume that all three loads have the same constant resistance, therefore in this case the system is balanced and the neutral ...
92 views

### SPWM vs SVPWM implementation [duplicate]

I am learning various control techniques for 3-Phase ACIMs. So far I have understood about the SPWM implementation.. in which we save Sin values in a LUT and then modulate the duty-cycle of PWM wave ...
254 views

### SPWM vs 6-step PWM vs SVMPWM

While learning 3-Phase scalar control of ACIM using STM32F407 MCU I could not clearly understand the diffrence between the following terms: 1. SPWM 2. 6-step PWM 3. SVMPWM How do they differ from ...