Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

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3-phase Voltage Measurement

I have a 3-phase system, where I measuring the Phase-Neutral voltage of each of the phases. Is it possible to calculate the Phase to Phase voltage from these values, even if the voltages are ...
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An unexpected behavior in my three-phase circuit simulation that I can't understand

For a working report on my university, I simply have the goal of testing the two-wattmeter method on a three-phase circuit with delta load which schematic can be seen below: It should be a very ...
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amperes too low on this circuit

I'm trying to get the voltage between phases, the line current and the apparent, real and reactive power of the next circuit: but there are a few things dazzling me, the most important is why the ...
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38 views

design 3phase vs single phase power supply 1500w

Whats the benefit of a 3phase power supply vs single phase power supply beside the higher power ratings? Is there difference in a power supply component's efficiency if designed for 3 phase vs single ...
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1answer
51 views

How to experimentally tune the current PI controllers in the synchronous reference frame?

I have been developing a control software for the grid connected three phase inverter i.e. for below given power electronics converter The control software implements below given control algorithm (...
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1answer
100 views

May I get 220v phase-neutral if all the homes in my state seems to give only 127v phase-neutral voltage on sockets? [closed]

Good morning. It is for didatic purposes only. I will just measure the voltage with a voltmeter. Nothing dangerous. In my state (São Paulo, Brazil), theres delta-star transformers that outputs 4-wires....
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1answer
69 views

How big of a breaker for 3 phase?

I'd like to buy 2 PDUs and choose the right circuit breaker for the circuit I'd put them on. Both PDUs are 30amp 3 phase and I'll be using 208V 3 phase power. Here is the power label. What I don't ...
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27 views

Filtering out switching noise from 3 phase mains

When connecting equipment to the 3 phase mains, I have noticed high distortions in the mains voltages. Here is a screenshot: Spikes are caused by high power motor controllers which are connected to ...
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1answer
52 views

Connecting a three phase electric motor to a single phase power supply

I would like to know what the cheapest and easiest way to connect a three phase 2.2kW AC induction motor to a single phase 230V power supply is. Also, in this setup, how can the motor be started and ...
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1answer
170 views

Determining the order of succession for a 3-phase current

On some exams the following question appeared that I am not capable of answering: How to determine the order of succession of the 3 phases of a 3-phase power using as a load either: a) 2 lamps and 1 ...
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2answers
42 views

How can i choose the right VFD for an electric motor?

I have a 1.5kW three phase electric motor that is in a delta configuration. This motor has a motor voltage of 230/400V and a rated current of 5.9/3.4A. What sort of VFD should i be looking for that ...
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1answer
29 views

Delta load vs Wye load

My answer for the first problem (Delta-Connected load) The Solution manual answer matches my answer: My answer for the second problem (Y-Connected load) However, the Solution manual answer does not ...
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99 views

How to transform the line voltages to the phase voltages in control software?

Let's say I am measuring line voltages of the three phase grid 400V/50Hz via three instrument transformers whose secondary windings are connected to the adc of my microcontroller i.e. I have following ...
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35 views

What's the meaning of three-phase reactive power of a three-phase device in balanced sinusoidal conditions?

I'm trying to make physical sense of the three-phase reactive power (a.k.a. total reactive power) for a three-terminal or four-terminal three-phase device (e.g. an AC motor, an AC generator, a load) ...
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35 views

3 phase controlled soft starter and motor vibration

I want to make a soft starter for 3 phase induction motors. TRs are SCR pairs and ZCs are the zero-cross timing respect to line voltages (400V), not phase voltages (230V). I control the firing angle ...
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Power-supply input power problem; single phase 220 V AC need to connect to 3-phase multi-voltage (208~520 V AC)

I bought POWER SUPPLY 3-PHASE, SMOOTHED. I used previous power supply 1-phase as following condition; Previous supply spec.: 960W 24V 40A Input: 1 phase 2 wire Output: 24V DC / around 20A Load: ...
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1answer
44 views

Replacing an AC drive in my mill and the use of a magnetic contactor in the power supply line

I have a small mill in my shop that I converted from single phase 110V 1hp motor to a 220V 3phase 2hp motor using a Teco Jnev 202. When I did that about 10 years ago I just wired it off a 30 A breaker ...
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1answer
44 views

In a delta generator, will each phase voltage always be shifted 120°?

I'm confused by all the different phases and angles. Where I live we have a delta generator (3P3W) 230 V system. I was told that the three voltage phases will always be shifted 120° from each other... ...
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2answers
77 views

Checking Phase sequence in a 3Ph. supply with uC

I am measuring the phase to neutral voltage in a 3 Ph. system. The ADC measures each of the phases in turn. All the voltages are scaled down and offset to center around 2.5V. The voltages are averaged ...
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73 views

Why does peak torque increase on increasing air gap in induction motor?

I have been trying for a while to summarize the effects of increasing air gap in an induction motor with constant load. I understand that increasing air gap with constant supply voltage demands high ...
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3answers
65 views

How to tap the full power of a 3-phase circuit

I know I can power my high voltage single phase AC or DC circuit by tapping either one of the L-1 to L-3 legs and return a neutral to the neutral line however I'll only get as much power from one 60Hz ...
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1answer
49 views

Common-mode choke on LTSpice

Can someone suggest to me how to select a three-phase common-mode choke with self and mutual inductance in LTSpice?
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1answer
80 views

Ringing problem Bootstrap for high side mosfet driver

I am using three phase half bridge inverter to power a PMSM motor and bootstrap for the high side MOSFET. The schematic is in attachment. Gate driver is Si8273, MOSFET is IPT015N10N5. But when I ...
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1answer
72 views

How to calculate power loss & voltage drop in three phase power cables

What is the correct formula/method to calculate cable power losses in a three phase system? i'm unable to find any IEC standard outlining the same. If you consider 3C/4C cables, the manufacturer ...
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2answers
132 views

RMS value calculation of 3 phase line voltages for power calculations

In my textbook in the power calculations section of the balanced three phase circuits, a part confused me a little bit, it is this part: Why are we dividing by \$\sqrt{3}\$ to find RMS values of \$V_{...
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1answer
125 views

(Electrical Misconduct) Two phases connected as three

I'm trying to be brief as best as I can, There are only two phases working (Red & Yellow), so the electrician shared Yellow phase between two terminals (as seen in the image), and of course will ...
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1answer
95 views

How to find rated current of a three phase induction motor

How to find the value of full load rated current and rated current for a three phase motor having its ratings as: ...
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30 views

Wye-connected alternator changed from wye to delta

A wye-connected alternator is rated at 20 amperes of line current. The internal connections are changed from wye to delta. What is the new line current rating? From what I understood, to get the line ...
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1answer
51 views

How to connect single-phase power source to 3-phase motor

My 3-phase, wye wound, 9-lead motor has: wires 1 & 7 connected to wire L1 2 & 8 connected to L2 3 & 9 connected to L3 and 4, 5, 6 wired together. I put a plug on one end of a cable, that ...
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2answers
2k views

What do the line-and-circle symbols mean on these electric meters?

I was looking at an electrical installation and came across unfamiliar symbols on the front of a pair of meters. These are from three-phase 240v meters running on a timed system. One each for peak/off-...
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57 views

Is it possible to obtain a sine wave with a 3 phase inverter?

In several pages, I have read that it is possible to obtain a sine wave (maybe with harmonics) from a three-phase inverter, with six transistors or thyristors, like this: I have seen some techniques, ...
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86 views

What type of three-phase connection does my shop have?

Yesterday, I wanted to test some MCBs and power supplies that I had just received. Since we only have one 480V socket in the shop, I asked my coworker if I could use the power source he was using. He ...
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2answers
69 views

Inconsistent 3-phase BLDC current

I come here because I am struggling to understand the signals coming from my 3 phase BLDC motor current. I am using a BLDC motor with a DRV8323RS driver in 1xPWM mode with Hall sensors. I measure the ...
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57 views

Three phase is 5 core (l1,l2,l3, N,G) yet my driver only has l1, l2, l3, G. What do I do with Neutral?

It's a motor driver and has connections for L1, L2, L3, and Ground -- by ground it's the universal ground symbol. My three phase cable has five connectors. I'm not happy with leaving one out, so is ...
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1answer
78 views

What can be the reason for a three phase fused socket to always blow the same fuse?

I am supplying a 30 kW load through a 3 phase socket. The socket is fused and the same fuse (same phase) is always blowing after a few hours of usage. What are the possible reasons for a single line ...
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1answer
46 views

How to model the three phase pwm rectifier?

I have been working on a dynamic model of the three phase pwm rectifier also known as active front end (AFE). The circuit diagram is following I have decided to solve that task this way: choose some ...
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3answers
79 views

How does electricity from a 3 phase 4 wire 480Y/277v EV meter differ from a standard 120v wall outlet?

I am wondering what the difference is the electricity that comes out of the switchboard/utility meter that is designed to be a separate meter to measure a customer's use of power that only goes to an ...
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4answers
965 views

Can I run a VFD off a generator?

I want to power a three-phase 5hp well pump with a VFD. I want the VFD both to serve as a soft start, and to allow variable speed operation of the motor. Two different pump salesmen have told me that ...
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1answer
56 views

House refurb rewire - low current?

So we've been renovating (virtually new everything) a 1930s semi that hasn't been modernised since it was built and hadnt been lived in since the 70s. Naturally a full rewire was high on the agenda ...
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3answers
119 views

Whats the justification to determine the phase sequence?

I have been told many times that one way to determinate the phase sequence of a three phase system is to use two resistances and one capacitor (or inductor) in star (wye) connection, then connect two ...
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2answers
52 views

Calculating kW of rotational power required by an engine to generate 3 phase power when phases are unbalanced

With respect to phase balance -- or lack thereof, if one phase is much higher than the others (for example 75, 100, 75) the total power according to my generator's display is 46 kW, but would the ...
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1answer
44 views

Help understand 3-phase generator load in amps in a mixed single and 3-phase grid

I have a 140 kVA, 440 V 3-phase 50 Hz generator running an aquaculture farm in Indonesia. There are 100 staff on site with the usual loads like freezers, light bulbs, TVs and water heaters etc. Also ...
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28 views

How can I calculate the RMS and Medium Voltage in a Controlled Three-phase Full-Wave Rectifier?

I want to calculate Vrms and Vmedium for the angles of 30º, 90º and 150º on the circuit above with and current source and a resistor load. I found a variety of formulas on the internet, but them all ...
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1answer
52 views

Three phase Induction motor directions

What are the directions of the rotor conductor, stator magnetic field, and rotor magnetic field? DOo they all have the same direction of rotation? How are they related to each other? Is the relative ...
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21 views

Three Phase IEC Equipment Ratings

Sometimes, when checking datasheets of Three Phase equipment, specs for "220-240 VAC" and "380-440 VAC" appears, as for these Mitsubishi Contactors Catalog AC-3 Power Ratings. ...
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64 views

Calculating the line-to-neutral voltage of a generator

A three-phase generator is connected to a strong grid with line-to-line voltage 14 kV and frequency 50 Hz. The generator is rated at 15 kV and 180 kVA. The resistance in the windings is 2 Ohm/phase ...
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31 views

Power measurement in star three phase balanced load

I had a doubt, in a balanced star three phase arrangement: Using two wattmeter method, we obtain power readings as W1 and W2. (which may be unequal). Let us take W1=5 watt and W2= 6 watt for instance ...
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1answer
51 views

3 phase cable equivalent circuit

I am trying to build an equivalent circuit for a 3-ph+N cable. Could you help me to identify the parameters. In the picture, you can find the primitive impedance matric for the cable and the proposed ...
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1answer
34 views

Can a 3 phase solid state relay be used instead of 3 single phase relays?

Apologies if this is similar to another question, but I did look before posting. I am trying to understand what exactly differentiates a 3-phase relay from a 1-phase relay. I am controlling three 1-...
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2answers
137 views

What is the difference between vectors and phasors?

I've seen both the terms vectors and phasors be used when it comes to AC circuits. I'm still kind of confused with how to clearly distinguish the two terms. I get that in a vague sense, the complex ...

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