Questions tagged [three-phase]
AC power with three legs run 120 degrees out of phase
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1answer
19 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 ...
0
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1answer
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 ...
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4answers
619 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 ...
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0answers
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 ...
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3answers
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 +/- ...
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1answer
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 ...
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0answers
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 ...
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3answers
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 ...
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1answer
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 ...
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0answers
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 ...
3
votes
1answer
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....
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33 views
Loading an AC generator with DC Chopper + resistor
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 ...
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1answer
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.
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2answers
75 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 ...
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vote
1answer
44 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 ...
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2answers
225 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 ...
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1answer
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 ...
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0answers
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 ...
3
votes
1answer
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 ...
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0answers
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 ...
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0answers
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 ...
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1answer
66 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 ...
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1answer
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/...
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0answers
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 ...
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0answers
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 (...
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1answer
89 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 ...
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2answers
249 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 ...
0
votes
1answer
86 views
3-phase motor (hi-hp) fails on start, insulation was > 500 megohms. WHY? [closed]
This is a common situation in industry where the 3-phase motor has a resistive reactance fault (as small as 1% unbalance) PRIOR to start. Insulation has been subject to excessive heating but meets ...
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1answer
27 views
Phase or Line V/F Control for ACIM
I am trying to implement V/F control for 3 phase ACIM using STM32F407 MCU. I am using 6 Complementary outputs of its Adv. Timer 1, Center aligned 256-points PWM waveform. The DC Bus voltage is 600 VDC....
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votes
1answer
38 views
how to get the line voltage of 3 phase delta circuit with power factor known at first?
In the following picture, it shows that a black box at right. the circuit inside the black box is a 3 phase load balanced delta connection circuit. the line voltage of it is 500V and the power factor ...
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1answer
59 views
Equivalent DC circuit of 3 phase induction motor
I'm currently trying to model a simplified circuit of an inverter + 3 phase induction motor. For now, I want to represent the DC link as an ideal independent voltage source. To keep this example ...
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1answer
50 views
Is it possible to design a three-phase delta generator only with two generators? [closed]
I've always seen 3 generators in a three-phase generator, but this question came to my mind. I've tried to add an element instead of the third generator, although with no result.
I hope someone can ...
0
votes
1answer
59 views
Balanced delta source to Wye source by considering magnitude only is ok?
I read and derived formulas for balanced delta source to Wye source; it is given by Vy = Vd / sqrt(3)<30 but in some places I see people only dividing by sqrt(3) for conversions are keeping angle 0,...
2
votes
1answer
46 views
Discrete simulation of 3-phase inductive load
I would like to make a discrete time simulation of a 3 phase inductive load but I am struggling with the problem. I have this Y configuration in mind.
I'd like to simulate each current and Vn, given ...
1
vote
1answer
61 views
3 phase - Unbalanced loads from line to line
In the case of a 3 phase wye unbalanced configuration such as the following:
we can compute the amount of current going through the neutral wire using geometry, in this case it is \$\sqrt{(\cos(150^{\...
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2answers
59 views
Poles of induction motor rotor
For a three phase squirrel cage induction motor (IM,) we can have 2 or 4 or 6 etc. pole pairs on its stator and when these stator windings are energized by 3 phase mains supply then we get a rotating ...
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2answers
35 views
Induction Motor Poles and Drive Configuration
If an IM is driven by a VVVF drive and the poles of the motor do not match with the drive configs.. eg., IM is 4 poles but the drive setting is 2 poles.. or the other way around.. then can it create a ...
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1answer
97 views
Wiring a 2 pole three-phase DB motor to a VFD
Hello everyone this is my first time posting here so forgive me if my post seems a little choppy. So my dilemma is trying to hook up a 2 pole three-phase DB motor rated at 230 X 3. I did a fair amount ...
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1answer
44 views
motor slip vs rotational speed
In Induction motor theory the term slip is used as normalized relative speed of the rotor to the synchronous speed and it depends on the physical rotational speed of the rotor.
Is there any special ...
0
votes
1answer
54 views
3 Phase calculations
I have 3-phase utility mains power supply whose phase voltage is 220 V, 50 Hz.
I keep getting confused about various calculations of the 3-phase mains as follows:
Formula for the line voltage.
...
1
vote
1answer
114 views
What is the practical use of Laplace Transform?
I am trying to understand the electrical model of 3-phase Induction Model. The rotor of the motor is modeled as a variable resistor in s-domain.
I fail to understand how that works practically. Can ...
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vote
3answers
110 views
What is line to line voltage supposed to meter at?
I'm pretty new to this but I know that in three phase power, when I'm metering line to line its usually at 208V, but I've been told that line to line meters at 240V. I don't know what would cause for ...
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0answers
36 views
Three-phase circuit with line impedance
I'm having some trouble with the first part of an exercise.
If I only have V1, and Zl, how can I find what the line voltage V2 is equal to? So that, then I could calculate the phase currents A1,A2,A3....
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2answers
206 views
Modelling 3-phase induction motor and filter for inverter output in LTspice
I am designing an inverter in Ltspice and am looking to have a simple circuit to represent the motor load and filter out the PWM harmonics in order to obtain outputs. The motor characteristics are:
...
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2answers
98 views
How to maintain a stable voltage on a Wind Turbine for Inverter
I'm doing some experiments on a wind turbine in my spare time.
At the moment, my system runs well and I can measure good output values from my generator. For example:
38V @18Hz at 30 RPM
97V @37Hz ...
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1answer
75 views
What should be switching voltage rating of relay in a 380VAC 3 phase system?
I am hooking up a system where there is 2 sources of power available. One source is the grid power, and the other is a generator. The grid provides me with 3-phase 380VAC with a neutral wire; and on ...
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1answer
34 views
What is the difference between a rupture and the neutral conductor not existing from the start in star three phased system?
I have a pretty basic question.
In three phased systems, I know that if the loads are equal, the neutal conductor has no role and can be removed, my question concerns unequal loads.
My question is, ...
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1answer
698 views
How can 400V & 690V on e-motors result in the same power
Forgive my ignorance, but how can two 3-phase ratings on the same motor result in the same output power?
The one I have is rated for 0.7kW in triangle for both 400V and 690V.
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1answer
88 views
Proper supply wiring for CNC router 4.1 kW 3Φ motor and 120 V accessories?
I'm building a CNC router table that has a three-phase 220 V spindle motor, and 120 V computer (and accessories). The spindle's nameplate:
As you can see it tops out at 20.3 A @ 220 V.
The VFD’s (...
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vote
1answer
715 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 ...
