Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

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PMSG connected to three-phase PWM rectifier - Simulink

I am implementing a controller for a three-phase rectifier in order to have a constant DC-link voltage. I have a PMSG which is connected to the rectifier and a capacitor (DC-link); I want to model ...
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1 answer
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How to distinguish bus voltage (in the context of network models) from line-to-neutral or line-to-line voltage (in the context of transformers)

Figure 7.2 (from Power Systems Analysis by Grainger/Stevenson) shows bus voltages Vm and Vn. From what I understand, Vm represents the potential difference between bus m and the reference bus I came ...
2 votes
2 answers
54 views

Meaning of 3P+N/2 in circuit breaker

In the following selection table of Legrand DPX3 three phase molded circuit breakers (Legrand 422000 to 422013) along with the familiar 3P and 4P circuit breakers, there are 3P+N/2 circuit breakers (...
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Is the two-wattmeter method applicable for an unbalanced source?

In balanced three-phase systems we can use the two-wattmeter method to measure total power. What about unbalanced sources and/or balanced/unbalanced loads? Can we use it for both delta and wye ...
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How do plug-in photovoltaic cells work with three-phase current electricity meters?

First off: I'm German, and while I have a bit of knowledge of electrical distribution systems, I am not too experienced with English terminology for the technical terms. So please bear with me. Also: ...
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Ramifications of voltage imbalance in a 3-phase motor

I have a 2.2 kW, 3-phase motor running a high pressure compressor. The supply mains voltage is very unbalanced. P1 221 V, P2 185 V, and P3 220 V under load (it should be 240 V). This is a 3rd world ...
2 votes
1 answer
39 views

How would a step-down transformer's secondary line-to-line current change when adding 3-phase motor loads?

I currently have a 45 kVA, 600 to 480 V, delta to wye step-down transformer designed into my system. I've done the calculation of 45 kVA / 480 V · √3 to roughly get 54.13 A. Would this current value ...
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1 answer
63 views

400 V, 3-phase electrical motor on 230 V, 3-phase supply WITHOUT rewiring?

I have a what I assume is a very unusual question, and an unusual situation. I do appologize if it has been explored before, but I could not find anything about it when searching. I also appologize ...
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Sinusoidal voltage on CAN bus signal wires when powered from 3 phase switching power supply

I am using CAN bus to communicate between this BLDC motor with a built in driver and a real-time control computer which uses a galvanically isolated Microchip MCP2561FDE/SN CAN transceiver. ...
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1 answer
41 views

ZNR rating difference between original and replacement PCB

I have a defective AC PCB and its potential replacement. The PCBs are near identical: same voltage zone, same micro controller... except the rating of their 4 ZNR components (surge protection) The ...
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PLL phase error plot confusion

I am working on the implementation of different PLL for grid-connected converters. I have confusion in a particular plot for my research which is the phase error. First of all, I generated the ...
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About voltage in power factor correction in three phase systems

So I understand that when you are correcting power factor you are decreasing the system's reactive power. This is usually done by adding capacitors, which also reduce the total current supplied by the ...
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1 answer
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Line to Line voltage in a three phase circuit with three loads

So the first load is a balanced, purely resistive one. The second one is unbalanced, and the third one is balanced. Diagram looks like this For the first load, I'm expecting to get line to line ...
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Why does 277/480V 600A 3 phase = 500 kVA and not 288 kVA?

According to an electrical engineer 277/480 V, 600 A, 3-phase is 500 kVA. I would like to understand more about why that is. I always thought 277 V x 1.73 = 480 V (and that's where 277/480 label comes ...
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5 answers
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What's the use of the 100 kΩ resistors in this schematic?

I saw a schematic for measuring AC voltage on a 3-phase mains supply (R/Y/B are the 3 phases and N is the neutral) I understand that the 1 MΩ and 2.7 kΩ resistors are for stepping down the voltage (...
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1 answer
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How to visually display 3 phase output

We have inherited a PCB and must redesign it. Unfortunately, only the PCB was provided, no schematics or documentation. I know the PCB controls a VFD (which we have been given) and whilst I know we ...
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What is the proper voltage for each phase of a 3 phase system

So i was checking voltages of a 3 phase system, so i checked the voltage of each phase going into my breaker with reference to ground, but what i got is something weird A - GND : 50 VAC B - GND : 200 ...
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3-phase inverter low side current sense

The setup I'm currently doing some experimentation with 3-phase inverters for BLDC motors and current sense. I have at hand this board featuring: IR2103 MOSFET driver. LIN# inputs are connected to ...
2 votes
4 answers
154 views

High voltage three phase power lines and ground danger

In Europe, most power lines have three cables for each phase and no neutral (usual UK line pictured): The three-phase AC generator at the power plant probably use a Δ-phase winding (simplified): (...
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14 votes
5 answers
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Is 3-phase power in any way better than split-phase power in a residential setting?

My understanding is that in the US (and Canada?) residential units receive split-phase 120V/240V power meaning the voltage between two phases is 2x the line-to-neutral voltage. Here in Europe ...
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2 answers
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What should I do with the neutral line while running 3-Phase induction motor?

As far as I've seen, low voltage distribution lines (3-Phase 440 volts) have four wires - three phases and one neutral (Ignore the earth cable). What should I do with the neutral line if I want to run ...
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Run normally 3-phase robot with batteries and single-phase domestic supply?

Apparently relatively small industrial robots (such as e.g. a Kuka with 12 - 20kg payload) require a peak 15kW electric supply that is used only to that peak at startup, and then much less ...
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Is the DC power input of a motor driver equal to the active power of a 3-phase motor on the output?

It is unclear to me how the DC power that is inputted into a motor driver is related to the 3-Phase power going to the motor from the driver. Is it correct to assume that the DC input power is equal ...
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Connecting A Three-Phase Motor for a Circular Saw

i have a table saw where i want to switch out the motor for a 3-phase one. I already have the motor and also a motor protection circuit, but i am not sure about how to connect it. This is the switch ...
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How to get stable current from three-phase alternating? [closed]

I have this generator. How can I convert a three-phase AC voltage into a DC voltage? I know that I can use a diode bridge to rectify the voltage, but how can I use it with a three-phase generator?
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Does the dropper between the catenary wire and contact wire carry current?

From my observations, droppers are of metal and they do not have any insulation from the catenary wire or from the contact wire. The catenary and contact both carry the same phase and voltage so any ...
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Waveform analysis of three-phase power

Purchased power metering equipment. The equipment is good... but the users are stupid. The line being measured supplies power in a short period of time and repeats receiving power. I want to know the ...
1 vote
2 answers
77 views

3-phase motor winding heater using DC current

The motor in use is a 3-phase 440V/37kW induction motor. I have received data regarding winding heaters from a motor manufacturer. If the rated voltage is 440V, a single-phase voltage of 24Vac must be ...
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Problem modeling capacitor bank for Three Phase Induction Motor

I'm currently working on a simulation in Simulink and I encountered a problem. I'm using a capacitor bank to improve the voltage drop at the output voltage of the motor. The problem is the capacitor ...
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1 answer
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Current calculation of three-phase system with "extra" resistors

I know you usually say that I should solve it a little bit and then ask for help, but in this question unfortunately I don't know where to start. This is a question about a three-phase circuit with ...
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Groundwater pump star-delta phase voltage confusion

Last time I got good answers for my question here so I came again today. Thanks. 🙏🙏 The problem am facing today is in star delta starting motor. When I connect motor to contactor, in phase to ground ...
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Voltage Drop Formula for Three Phase Power Systems

I've just started learning about electricity and power systems, and am currently learning about calculating voltage drop for three phase power systems. The book I am reading is explaining how to ...
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Apparent power for assymetric configurations

I know that the total apparent power S in a 3 phase load for Wye-Wye or D-D configuration = sqrt(3)Vline*Iline. Is it the same for Wye-D or D-Wye configuration?
2 votes
1 answer
108 views

Why is one current reading ~20% higher than the other two in a balanced high-leg delta load?

We are using eGuage watthourmeters to monitor the outdoor unit on five VRF systems powered by two different 3P4W 120/208V high-leg delta panels. The neutral is not connected to the outdoor units. We ...
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Modeling three phase load for EV charger

When designing a power system to supply EV charging stations, are the stations modeled as delta loads or wye loads? Slightly off topic but is it standard practice to assume that three phase loads are ...
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STM8L ADC multiple channel read problem

I am using an STM8L151Cx with the Cosmic C compiler to develop a 3 phase ammeter. I rsn into an issue during my last stage of development. 3 phase current is connected to 3 channels in the controller ...
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1 vote
1 answer
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Relation between line voltage and phase voltage in delta configuration

I have read answers pertaining to this same question, but I could not understanf why the phase voltage is equal to line voltage. This answer says: In a delta system, the two points required to ...
3 votes
1 answer
83 views

How to determine phase sequence of the unbalanced three phase grid?

Let's say I have three phase voltage grid which is unbalanced (three phase utility grid). The phase voltages are sampled by the adc (suppose that the analog channel is properly designed from the hw ...
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What is the relationship between 3 phase motor driving signal and its position encoder?

I have this project to add a magnetic encoder on the motor shaft that will allow speed control by utilizing a TB67B000AHG chip as a driver. I want to install 3 magnetic Hall sensors HW101 stationary ...
1 vote
2 answers
106 views

How to decompose the three phase unbalanced grid into the symmetrical components?

Let's I have three phase voltage grid which is unbalanced. The phase voltages are sampled by the adc and I would like to determine in the C language software the positive sequence, negative sequence ...
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Kiln SSR zero-cross frequency

I am planning on using a WATLOW DC2T-24C0-0000 power controller for a three phase electric kiln. It is a zero-cross 3 phase, 2 leg controlled contactor capable of driving 46 amps with its huge heat ...
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1 answer
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How is the winding cross-induction of a 3 phases motor magnetically interact from one winding to the next?

Considering a Squirrel Cage 3 phases motor. A multi-switch receive the 3 lines of the 3Ø power L1 L2 L3 and distribute the voltage to 6 wires. The multi-switch has 3 position, Speed 1 , OFF , Speed 2,...
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1 answer
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Problem with using 8 channel 433mhz 12 v relay module to control an overhead crane [closed]

I have recently tried to retrofit an existing overhead crane with a 8 channel 433mhz 12 v relay module with a receiver and a transmitter I bought online. My existing crane already has a button pendant ...
1 vote
2 answers
664 views

How to calculate length needed for heating element (2mm Nickeline/Nichrome wire) to a specified power?

to start off, i dont really understand about electrical engineering. im a mechanical engineering student tasked to continue the project. i dont really understand electrical stuff beside the very basic ...
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I need help with PWM filter capacitor current calculation

PWM filter capacitor current calculation. I am trying to select the capacitor for the PWM filter shown below. That being the case, I need to calculate the total current (fundamental + harmonics) ...
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1 answer
130 views

Calculate power output of 3 phase generator - uneven sine wave

I am using this BLDC motor [https://uav-en.tmotor.com/html/2018/navigato_0402/52.html] as a generator. The device providing the mechanical drive turns the motor about half a turn and not at a linear ...
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A/C generator = RPC?

I need 3ph power to run metalworking machines in my home shop. I've landed on utilizing a rotary phase converter to accomplish this. Some time ago, I took a 10kw 3ph generator on trade for some work....
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How do you calculate electrical active (3-phase) power with L1,L2,L3 (I) angles to L1 (U) and L1,L2,L3 (I) and L1,L2,L3-N (U) measurement?

I get from a Landis+Ggyr E650 electricity meter data via a serial IR head (62056-21 / D0) about every 20s. This meter provides a lot of data, but not the current actual active power (kW). Some of the ...
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Are 3P+N circuit breakers designed to make neutral first and break neutral last?

Consider a CEE 60309 connector, 3P + N + PE. The pins have equal length, but the conductive sleeve matching up with the pins dont have the same length; and of particular interest is that the neutral ...
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1 answer
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Need help with simulation of three-phase active rectifier on LTSPICE

I have already successfully simulated a three-phase rectifier on simulink. However, I wish to implement the same on LTspice because I would have liked to see the effect of using non-ideal components. ...

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